CSET Study Guide: General Science

SMR 2.6.e: Interpret simple series and parallel circuits.

A circuit is a complete path through which an electrical current (or stream or electrons) can flow. The path starts at one terminal of the power source (for example, the negative battery terminal or a terminal of a direct current power source) and ends at the other. A simple series circuit consists of: - wires through which electrical charge flows - a battery or power supply to provide the voltage to push charge around the circuit (that is, to drive the circuit) - a switch to interrupt the current - a resistor (which dissipates energy) - a light bulb or other component, which works when current flows through it The components in a series circuit--batteries, switches, resistors, bulbs, and so on--are connected in a simple loop, like beads on a necklace. In this circuit, you will use a battery and wire to light up a bulb. There are several incorrect ways to build this circuit. For example, a student might: - connect one battery terminal to the bulb - connect the bulb to one terminal and connect the terminals The correct way is to connect one terminal of the battery to the light, then connect the light to the other terminal of the battery. In this circuit, current flows from a battery through a switch (when it is closed), then through a bulb, and back to the battery. The current flows simultaneously through all parts of the circuit. The current is present everywhere in the wires and components. When the switch is closed, electrical charges start moving from everywhere at once. To build this circuit: - Attach one end of the wire to one terminal of a battery or to the terminal labeled "1.5 Volt" of a DC power supply. (The clips on the end of the wire are called alligator clips.) - Attach the other end of the wire to one end of the switch (the switch should be open when you set up the circuit). - Using another wire, connect the other end of the switch to one of the screws at the base of the light bulb component. (In some setups, you must twist the wire around the screw to make electrical contact.) - Then run a wire from the second light bulb screw to the terminal labeled "common" on the power supply. A current flows through the circuit when the switch is closed. Opening the switch causes the current to stop flowing. A break elsewhere along the circuit will also cause the current to stop. For example, unscrewing or removing a light bulb will stop the current in the entire circuit. This circuit introduces the resistor. A resistor function like a flow restrictor on a showerhead, "resisting" the current and limiting the flow of electrons. At the atomic level, resistance comes from the collisions that electrons undergo with atoms in the wire. In each collision, an electron that is helping to carry the current in the circuit loses a little bit of energy. Different types of conducting materials offer different levels of resistance. Resistance of a wire also depends on the length and diameter of the wire. -The longer the wire, the greater the resistance. - The smaller the cross-sectional area or diameter of the wire, the greater the resistance. Ordinary copper wires used in constructing simple circuits have some small resistance. But often, in calculating the resistance in a circuit, one assumes all the resistance is in the resistor components, and none in the wires. In this circuit, current flows from a battery through a resistor, a light bulb, another resistor, and another light bulb. When the circuit is connected and the current flows, the bulbs light up and get warm as they dissipate energy in the form of heat and light. The resistors also warm up as they dissipate energy. Unscrewing one bulb or removing one component breaks the current through the entire circuit. If a bulb burns out, the filament breaks, and this also breaks the electrical path. In a parallel circuit, the electrical current flows in two or more closed paths simultaneously. In this circuit, one path includes a battery, switch 1, and light bulb a. The other path includes the same battery, switch 1, switch 2, and two light bulbs b and c. When switches 1 and 2 are both closed, current flows through bulbs a, b, and c simultaneously. If light bulb a is unscrewed, bulbs b and c stay on. If switch 1 is closed and bulb a is screwed in, and switch 2 is opened, current continues to flow through a. The two branches of the circuit are independent. In a household, appliances are connected in parallel. If the stove, the refrigerator, and the microwave were connected in series, and one was removed--say, the microwave--then the fridge wouldn't work! This illustrates one general disadvantage of series circuits: if one component fails, the rest do not work. Another disadvantage of series circuits: as components are added, the resistance in the circuit increases and the current through the circuit is reduced. If you add a light bulb in series to an existing string of bulbs, each one will be a little dimmer. A disadvantage of parallel circuits: as components are added, more energy is drawn from the power supply. More current flows through the circuit and the wires or components may melt or catch fire. (Fuses are used to protect such circuits). https://uciunex.instructure.com/courses/9455/pages/introduction-to-circuits?module_item_id=479326

SMR 1.1.c: Apply knowledge of planning and conducting scientific investigations, including safety considerations and the use of appropriate tools and technology.

To conduct a scientific investigation: 1. Make an observation. 2. Ask a question. 3. Do background research to search for existing answers or solutions. 4. Construct a hypothesis to answer your question. 5. Design and perform an experiment. 6. Analyze data to accept or reject the hypothesis. 7. Draw conclusions based on your hypothesis. 8. If results align with the hypothesis, communicate results. If they do not, ask a new question and repeat the process. Safety considerations: - Follow instructions and be attentive. - Have proper supervision. - Know the location of safety equipment. - Know what hazard symbols mean. - Know what to do in case of an accident. - Dress appropriately (close-toed shoes and goggles are a must!) - Keep a clean workspace. - Handle glassware carefully. - Do not taste or sniff chemicals. - Do not eat or drink in a lab. - Dispose of waste properly. From NGSS: Scientists and engineers plan and carry out investigations in the field or laboratory, working collaboratively as well as individually. Their investigations are systematic and require clarifying what counts as data and identifying variables or parameters. - Plan an investigation individually or collaboratively, and in the design: identify independent and dependent variables and controls, what tools are needed to do the gathering, how measurements will be recorded, and how many data are needed to support a claim. - Conduct an investigation and/or evaluate and/or revise the experimental design to produce data to serve as the basis for evidence that meets the goals of the investigation. - Evaluate the accuracy of various methods for collecting data. - Collect data to produce data to serve as the basis for evidence to answer scientific questions or test design solutions under a range of conditions. - Collect data about the performance of a proposed object, tool, process, or system under a range of conditions. Students should have opportunities to plan and carry out several different kinds of investigations during their K-12 years. At all levels, they should engage in investigations that range from those structured by the teacher--in order to expose an issue or question that they would be unlikely to explore on their own (e.g., measuring specific properties of materials)--to those that emerge from students' own questions. Scientific investigations may be undertaken to describe a phenomenon, or to test a theory or model of how the world works. The purpose of engineering investigations might be to find out how to fix or improve the functioning of a technological system or to compare different solutions to see which best solves a problem. Students should design investigations that generate data to provide evidence to support claims they make about phenomena. Planning and carrying out investigations may include elements of all the other practices. https://ngss.nsta.org/Practices.aspx?id=3

SMR 3.3.b: Demonstrate knowledge of the interrelationships within and among ecosystems and recognize factors that affect population types, size, and carrying capacity in ecosystems (e.g., availability of biotic and abiotic resources, predation, competition, disease).

- An ecological community consists of all the populations of all the different species that live together in a particular area. - Interactions between different species in a community are called interspecific interactions--inter- means "between." - Different types of interspecific interactions have different effects on the two participants, which may be positive (+), negative (-), or neutral (0). - The main types of interspecific interactions include competition (-/-), predation (+/-), mutualism (+/+), commensalism (+/0), and parasitism (+/-). When we took a tour through population ecology, we mostly looked at populations of individual species in isolation. In reality, though, populations of one species are rarely--if ever!--isolated from populations of other species. In most cases, many species share a habitat, and the interactions between them play a major role in regulating population growth and abundance. Together, the populations of all the different species that live together in an area make up what's called an ecological community. For instance, if we wanted to describe the ecological community of a coral reef, we would include the populations of every single type of organism we could find, from coral species to fish species to the single-celled, photosynthetic algae living in the corals. For a healthy reef, that comes out to a whole lot of different species! Community ecologists seek to understand what drives the patterns of species coexistence, diversity, and distribution that we see in nature. A core part of how they address these questions is by examining how different species in a community interact with each other. Interactions between two or more species are called interspecific interactions--inter- means "between." In the rest of this article, we'll take take a look at the main types of interspecies interactions seen in ecological communities. Here is a quick preview: - Competition is when organisms of two species use the same limited resource and have a negative impact on each other, and the effect is (-/-). - Predation is when a member of one species, predator, eats all or part of the body of a member of another species, prey, and the effect is (+/-). - Herbivory is a special case of predation in which the prey species is a plant, and the effect is (+/-). - Mutualism is a long-term, close association between two species in which both partners benefit, and the effect is (+/+). - Commensalism is a long-term, close association between two species in which one benefits and the other is unaffected, and the effect is (+/0). - Parasitism is a long-term, close association between two species in which one benefits and the other is harmed, and the effect is (+/-). Interspecies interactions can be broken into three main categories: competition, predation, and symbiosis. Let's take a closer look at each. In interspecific competition, members of two different species use the same limited resource and therefore compete for it. Competition negatively affects both participants (-/- interaction), as either species would have higher survival and reproduction if the other was absent. Species compete when they have overlapping niches, that is, overlapping ecological roles and requirements for survival and reproduction. Competition can be minimized if two species with overlapping niches evolve by natural selection to utilize less similar resources, resulting in resource partitioning. In predation, a member of one species--the predator--eats part or all of the living, or recently living, body of another organism--the prey. This interaction is beneficial for the predator, but harmful for the prey (+/- interaction). Predation may involve two animal species, but it can also involve an animal or insect consuming part of a plant, a special case of predation known as herbivory. Predators and prey regulate each other's population dynamics. Also, many species in predator-prey relationships have evolved adaptations--beneficial features arising by natural selection--related to their interaction. On the prey end, these include mechanical, chemical, and behavioral defenses. Some species also have warning coloration that alerts potential predators to their defenses; other harmless species may mimic this warning coloration. Symbiosis is a general term for interspecific interactions in which two species live together in a long-term, intimate association. In everyday life, we sometimes use the term symbiosis to mean a relationship that benefits both parties. However, in ecologist-speak, symbiosis is a broader concept and can include close, lasting relationships with a variety of positive or negative effects on the participants. In a mutualism, two species have a long-term interaction that is beneficial to both of them (+/+ interaction). For example, some types of fungi form mutualistic associations with plant roots. The plant can photosynthesize, and it provides the fungus with fixed carbon in the form of sugars and other organic molecules. The fungus has a network of threadlike structures called hyphae, which allow it to capture water and nutrients from the soil and provide them to the plant. In a commensalism, two species have a long-term interaction that is beneficial to one and has no positive or negative effect on the other (+/0 interaction). For instance, many of the bacteria that inhabit our bodies seem to have a commensal relationship with us. They benefit by getting shelter and nutrients and have no obvious helpful or harmful effect on us. It's worth noting that many apparent commensalisms actually turn out to be slightly mutualistic or slightly parasitic (harmful to one party, see below) when we look at them more closely. For instance, biologists are finding more and more evidence that our normal microbial inhabitants play a key role in health. In a parasitism, two species have a close, lasting interaction that is beneficial to one, the parasite, and harmful to the other, the host (+/- interaction). Some parasites cause familiar human diseases. For instance, if there is a tapeworm living in your intestine, you are the host and the tapeworm is the parasite--your presence enhances the tapeworm's quality of life, but not vice versa! - In nature, population size and growth are limited by many factors. some are density-dependent, while others are density-independent. - Density-dependent limiting factors cause a population's per capita growth rate to change--typically, to drop--with increasing population density. One example is competition for limited food among members of a population. - Density-independent factors affect per capita growth rate independent of population density. Examples include natural disasters like forest fires. - Limiting factors of different kinds can interact in complex ways to produce various patterns of population growth. Some populations show cyclical oscillations, in which population size changes predictably in a cycle. All populations on Earth have limits to their growth. Even populations of bunnies--that reproduce like bunnies!--don't grow infinitely large. And although humans are giving the idea of infinite growth a run for its money, we too will ultimately reach limits on population size imposed by the environment. What exactly are these environmental limiting factors? Broadly speaking, we can split the factors that regulate population growth into two main groups: density-dependent and density-independent. Let's start off with an example. Imagine a population of organisms--let's say, deer--with access to a fixed, constant amount of food. When the population is small, the limited amount of food will be plenty for everyone. But, when the population gets large enough, the limited amount of food may no longer be sufficient, leading to competition among the deer. Because of the competition, some deer may die of starvation or fail to have offspring, decreasing the per capita--per individual--growth rate and causing population size to plateau or shrink. In this scenario, competition for food is a density-dependent limiting factor. In general, we define density-dependent limiting factors as factors that affect the per capita growth rate of a population differently depending on how dense the population already is. Most density-dependent factors make the per capita growth rate go down as the population increases. This is an example of negative feedback that limits population growth. Density-dependent limiting factors can lead to a logistic pattern of growth, in which a population's size levels off at an environmentally determined maximum called the carrying capacity. Sometimes this is a smooth process; in other cases, though, the population may overshoot carrying capacity and be brought back down by density-dependent factors. Density-dependent factors tend to be biotic--living organism-related--as opposed to physical features of the environment. Some common examples of density-dependent limiting factors include: - Competition within the population. When a population reaches a high-density, there are more individuals trying to use the same quantity of resources. This can lead to competition for food, water, shelter, mates, light, and other resources needed for survival and reproduction. - Predation. Higher-density populations may attract predators who wouldn't bother with a sparser population. When these predators eat individuals from the population, they decrease its numbers but may increase their own. This can produce interesting, cyclical patterns, as we'll see below. - Disease and parasites. Disease is more likely to break out and result in deaths when more individuals are living together in the same place. Parasites are also more likely to spread under these conditions. - Waste accumulation. High population densities can lead to the accumulation of harmful waste products that kill individuals or impair reproduction, reducing the population's growth. Density-dependent regulation can also take the form of behavioral or physiological changes in the organisms that make up the population. For example, rodents called lemmings respond to high population density by emigrating in groups in search of a new, less crowded place to live. This process has been misinterpreted as a mass suicide of sorts in popular culture because the lemmings sometimes die while trying to cross bodies of water. The second group of limiting factors consists of density-independent limiting factors that affect per capita growth rate independent of how dense the population is. As an example, let's consider a wildfire that breaks out in a forest where deer live. The fire will kill any unlucky deer that are present, regardless of population size. An individual deer's chance of dying doesn't depend at all on how many other deer are around. Density-independent limiting factors often take the form of natural disasters, severe weather, and pollution. Unlike density-dependent limiting factors, density-independent limiting factors alone can't keep a population at constant levels. That's because their strength doesn't depend on the size of the population, so they don't make a "correction" when the population size gets too large. Instead, they may lead to erratic, abrupt shifts in population size. Small populations may be at risk of getting wiped out by sporadic, density-independent events. In the real world, many density-dependent and density-independent limiting factors can--and usually do--interact to produce the pattern of change we see in a population. For example, a population may be kept near carrying capacity by density-dependent factors for a period then experience an abrupt drop in numbers due to a density-independent event, such as a storm or fire. However, even in the absence of catastrophes, populations are not always stably at carrying capacity. In fact, populations can fluctuate, or vary, in density in many different patterns. Some undergo irregular spikes and crashes in numbers. For instance, algae may bloom when an influx of phosphorous leads to unsustainable growth of the population. Other populations have regular cycles of boom and bust. Let's take a closer look at these cycles. Some populations undergo cyclical oscillations in size. Cyclical oscillations are repeating rises and drops in the size of the population over time. If we graphed population size over time for a population with cyclical oscillations, it would look roughly like the wave below--though probably not quite as tidy! Where do these oscillations come from? In many cases, oscillations are produced by interactions between populations of at least two different species. For instance, predation, parasite infection, and fluctuation in food availability have all been shown to drive oscillations. These density-dependent factors don't always create oscillations, however. Instead, they only do so under the right conditions, when populations interact in specific ways. As an example, let's look at a population of lemmings found in Greenland. For years, this population had cyclical oscillations in size, with a period--the length of a full cycle--of about four years. Ecologists found that the cycle could be explained by interactions between the lemming and four predators: the owl, fox, skua--a bird--and stoat. The owl, fox, and skua are opportunistic predators that can use various food sources and tend to eat lemmings only when they are abundant. The stoat, in contrast, eats pretty much only lemmings. So, why does the cycle happen? Let's start by following the lemmings at their low point in the cycle. Because the population density is low, the owls, skuas, and foxes will not pay too much attention to the lemmings, allowing the population to increase rapidly. As the lemming population grows, the stoat population grows, but with a lag. This reflects that stoats reproduce only once a year--unlike lemmings, which reproduce more or less constantly--and can only leave numerous offspring after they've had a period in which their food source, lemmings, is abundant. As the lemming density increases, owls, foxes, and skuas are attracted and start preying on the lemmings more frequently than when they were scarce. This acts as a density-dependent limit to lemming growth, and it keeps lemmings from getting ahead of the stoats in numbers. The stoat population thus overshoots and becomes large enough that it kills off many of the lemmings, leaving few to reproduce and causing a lemming population crash. This crash is followed by a stoat crash with a one-year delay, as the stoats wind up with a greatly reduced food supply. And then the cycle begins again. The general pattern of interaction is represented in the graph below. You can see that prey population numbers--such as those of lemmings--drop first and are then followed by predator numbers--such as those of the stoat. Are other factors besides predator-prey interactions driving this pattern? It's possible, but ecologists were able to reproduce the oscillating pattern in a computer model based only on predation and reproduction data from the field, supporting the idea that predation is a driving factor. Sad fact: some lemming populations are no longer oscillating. They peaked--per their usual cycle--in 1998 but never recovered from the crash that followed. Ecologists think this may be due to unusually warm winters and changes in snowfall in the Arctic, which may have reduced the snowpack that usually provides protection to the lemmings as they raise their young. As a result, species that are predators of lemmings may die out in regions where the lemming populations have crashed. One other famous example of this type of predator-prey interaction involves the Canada lynx--the predator--and the snowshoe hare--the prey--whose populations have been shown to co-vary in cycles, with a drop in hare numbers predicting a drop in lynx numbers. This is the example you're most likely to see in your textbook. At first, scientists thought that lynx predation was the key factor that made the hare population drop. We now know that other factors are likely involved, such as availability of food for the hares. Either way, this is another example in which density-dependent factors produce cyclical changes in a population.

SMR 3.3.d: Demonstrate knowledge of possible solutions for minimizing human impact on ecosystem resources and biodiversity.

- Biodiversity: The variety of organisms in an ecosystem. - Renewable resources: Resources that are replaced as quickly as they are used. - Nonrenewable resources: Resources that are limited in supply because they are used faster than can be replaced. - Conservation: The study of the loss of Earth's biodiversity and the ways this loss can be prevented. - Extinction: Process during which all members of a group of organisms die out. - Endangered species: Species that has been identified as likely to become extinct. - Biodiversity hotspot: A biogeographic region that contains high biodiversity and is also threatened with destruction. - Climate change: Measurable long-term changes in Earth's climate. Human activity is a major threat to the planet's biodiversity. This is because human population growth thus far has been exponential, meaning that its growth rate stays the same regardless of population size. This makes the population grow faster and faster as it gets larger. Populations may grow exponentially for some period, but they ultimately reach a carrying capacity when they become limited by resource availability. Humans, however, have continued to work around carrying capacity as they develop new technologies to help support the ever-growing population. This threatens biodiversity because the more humans there are, the more this displaces other species and reduces species richness. - LAND-USE CHANGE: Humans may destroy natural landscapes as they mine resources and urbanize areas. This is detrimental, as it displaces residing species, reducing available habitats and food sources. - POLLUTION: Pollution can occur from the runoff or disposal of chemical substances, or from energy sources (noise and light pollution). - INTRODUCED SPECIES: Humans may unintentionally, or intentionally, introduce a non-native species into an ecosystem. This can negatively effect an ecosystem because the introduced species may outcompete native organisms and displace them. - RESOURCE EXPLOITATION: Humans consume large amounts of resources for their own needs. Some examples include the mining of natural resources like coal, the hunting and fishing of animals for food, and the clearing of forests for urbanization and wood use. Extensive overuse of nonrenewable resources, like fossil fuels, can cause great harm to the environment. Recycling products made from nonrenewable resources (such as plastic, which is made from oil) is one way to reduce the negative impacts of this resource exploitation. In addition, the development and use of renewable resources, like solar or wind energy, can help decrease the harmful effects of resource exploitation. The current climate change Earth is facing is caused by the increase in global temperatures. Human activity is changing Earth's atmosphere faster than it has ever changed during its history. The burning of fossil fuels and the growth of animal agriculture has led to large amounts of greenhouse gases (such as carbon dioxide and methane) in the atmosphere. Higher concentrations of greenhouse gases trap more heat in the biosphere and result in global warming. In turn, this drives climate change. When climate change affects an environment so much that it is unable to sustain organisms, they must adapt, relocate, or face extinction. Because of this, climate change can have a huge effect on biodiversity. Conservation efforts work to protect species and the places in which they live. There are many different kinds of conservation efforts. Species protection is one way to help combat extinction. Although extinction is a natural process, it is occurring at a much faster, much higher rate than normally expected. The creation of local, national, and international legislation can help prevent the loss of endangered species. In addition, captive-breeding programs may help protect endangered species by maintaining a healthy population of endangered species in captivity. Habitat protection, preservation, and restoration is essential in protecting biodiversity. This ensures that the protected species have places to live that can support them. Ultimately, saving one habitat can have a cascading effect, and help to protect an entire ecosystem. Scientists have determined several biodiversity hotspots, which are a high priority for protecting. The extinction rate is currently 1,000-10,000 times higher than the natural extinction rate. Some people think that extinction is not a relevant issue, but it is actually more relevant than ever! Historically, the natural extinction rate is between 1-5 species-level extinctions per year. Human impact has caused this rate to jump to a significantly higher rate, offsetting the balance of biodiversity. The greenhouse effect is not all negative. Although we talk about greenhouse gases producing a negative impact (global change), the greenhouse effect serves a natural purpose: maintaining the warmth that sustains life on Earth. The problem arises when too much heat is trapped, causing a rise in average global temperature. An individual person can have an effect on biodiversity. Although biodiversity loss may be a large-scale problem, reducing threats to biodiversity can begin with a single individual. Smaller efforts, such as reusing or recycling items, or even purchasing sustainable foods, can have a culminating effect. That is, if each person did these things, even just a little, they would add up and help reduce biodiversity loss!

SMR 3.4.b: Apply knowledge of the structure of DNA and the process of DNA replication.

- DNA (deoxyribonucleic acid): Nucleic acid that transmits genetic information from parent to offspring and codes for the production of proteins. - Nucleotide: Building block of nucleic acids. - Double helix: Structure of two strands, intertwining around an axis like a twisted ladder. - DNA replication: Process during which a double-stranded DNA molecule is copied to produce two identical DNA molecules. - Base pairing: Principle in which the nitrogenous bases of the DNA molecules bond with one another. DNA is a nucleic acid, one of the four major groups of biological macromolecules. All nucleic acids are made up of nucleotides. In DNA, each nucleotide is made up of three parts: a 5-carbon sugar called deoxyribose, a phosphate group, and a nitrogenous base. DNA uses four kinds of nitrogenous bases: adenine (A), guanine (G), cytosine (C), and thymine (T). RNA nucleotides may also contain adenine, guanine and cytosine bases, but instead of thymine they have another base called uracil (U). In the 1950s, a biochemist named Erwin Chargaff discovered that the amounts of the nitrogenous bases (A, T, C, and G) were not found in equal quantities. However, the amount of A always equalled the amount of T, and the amount of C always equalled the amount of G. These findings turned out to be crucial to uncovering the model of the DNA double helix. The discovery of the double helix structure of DNA was made thanks to a number of scientists in the 1950s. DNA molecules have an antiparallel structure--that is, the two strands of the helix run in opposite directions of one another. Each strand has a 5' end and a 3' end. Solving the structure of DNA was one of the great scientific achievements of the century. Knowing the structure of DNA unlocked the door to understanding many aspects of DNA's function, such as how it is copied and how the information it carries can be used to produce proteins. DNA replication is semi-conservative. This means that each of the two strands in double-stranded DNA acts as a template to produce two new strands. Replication relies on complementary base pairing, that is the principle explained by Chargaff's rules: adenine (A) always bonds with thymine (T) and cytosine (C) always bonds with guanine (G). DNA replication occurs through the help of several enzymes. These enzymes "unzip" DNA molecules by breaking the hydrogen bonds that hold the two strands together. Each strand then serves as a template for a new complementary strand to be created. Complementary bases attach to one another (A-T and C-G). The primary enzyme involved in this is DNA polymerase which joins nucleotides to synthesize the new complementary strand. DNA polymerase also proofreads each new DNA strand to make sure that there are no errors. DNA is made differently on the two strands at a replication fork. One new strand, the leading strand, runs 5' to 3' towards the fork and is made continuously. The other, the lagging strand, runs 5' to 3' away from the fork and is made in small pieces called Okazaki fragments. DNA is only synthesized in the 5' to 3' direction. You can determine the sequence of a complementary strand if you are given the sequence of the template strand. For instance, if you know that the sequence of one strand is 5'-AATTGGCC-3', the complementary strand must have the sequence 3'-TTAACCGG-5'. This allows each base to match up with its partner. - DNA replication is not the same as cell division. Replication occurs before cell division, during the S phase of the cell cycle. However, replication only concerns the production of new DNA strands, not of new cells. - Some people think that in the leading strand, DNA is synthesized in the 5' to 3' direction, while in lagging strand, DNA is synthesized in the 3' to 5' direction. This is not the case. DNA polymerase only synthesizes DNA in the 5' to 3' direction only. The difference between the leading and lagging strands is that the leading strand is formed towards replication fork, while the lagging strand is formed away from replication fork.

SMR 2.2.c: Describe the effect of temperature, pressure, and concentration on chemical equilibrium (Le Chatelier's Principle) and reaction rate.

- Le Chatelier's principle can be used to predict the behavior of a system due to changes in pressure, temperature, or concentration. - Le Chatelier's principle implies that the addition of heat to a reaction will favor the endothermic direction of a reaction as this reduces the amount of heat produced in the system. - Increasing the concentration of reactants will drive the reaction to the right, while increasing the concentration of products will drive the reaction to the left. - Equilibrium: The state of a reaction in which the rates of the forward and reverse reactions are the same. - Collision theory: Relates collisions among particles to reaction rate; reaction rate depends on factors such as concentration, surface area, temperature, stirring, and the presence of either a catalyst or an inhibitor. Le Chatelier's principle is an observation about chemical equilibria of reactions. It states that changes in the temperature, pressure, volume, or concentration of a system will result in predictable and opposing changes in the system in order to achieve a new equilibrium state. According to Le Chatelier's principle, adding additional reactant to a system will shift the equilibrium to the right, towards the side of the products. By the same logic, reducing the concentration of any product will also shift equilibrium to the right. The converse is also true. If we add additional product to a system, the equilibrium will shift to the left, in order to produce more reactants. Or, if we remove reactants from the system, equilibrium will also be shifted to the left. Thus, according to Le Chatelier's principle, reverse reactions are self-correcting; when they are thrown out of balance by a change in concentration, temperature, or pressure, the system will naturally shift in such a way as to "re-balance" itself after the change. As the concentration of CO is increased, the frequency of successful collisions of that reactant would increase as well, allowing for an increase in the forward reaction, and thus the generation of the product. A change in pressure or volume will result in an attempt to restore equilibrium by creating more or less moles of gas. For example, if the pressure in a system increases, or the volume decreases, the equilibrium will shift to favor the side of the reaction that involves fewer moles of gas. Similarly, if the volume of a system increases, or the pressure decreases, the production of additional moles of gas will be favored. When the volume of the system is changed, the partial pressures of the gases change. The system tries to counteract the decrease in partial pressure of gas molecules by shifting to the side that exerts greater pressure. Similarly, if we were to increase pressure by decreasing volume, the equilibrium would shift to the right, counteracting the pressure increase by shifting to the side with fewer moles of gas that exert less pressure. Lastly, for a gas-phase reaction in which the number of moles of gas on both sides of the equation are equal, the system will be unaffected by changes in pressure. The effect of temperature on equilibrium has to do with the heat of reaction. If we picture heat as a reactant or a product, we can apply Le Chatelier's principle just like we did in our discussion on raising or lowering concentrations. For instance, if we raise the temperature on an endothermic reaction, it is essentially like adding more reactant to the system, and therefore, by Le Chatelier's principle, the equilibrium will shift to the right. Conversely, lowering the temperature on an endothermic reaction will shift the equilibrium to the left, since lowering the temperature in this case is equivalent to removing a reactant. For an exothermic reaction, heat is a product. Therefore, increasing the temperature will shift the equilibrium to the left, while decreasing the temperature will shift the equilibrium to the right. Catalysts speed up the rate of a reaction, but do not have an affect on the equilibrium position. Recall that for a reversible reaction, the equilibrium state is one in which the forward and reverse reaction rates are equal. In the presence of a catalyst, both the forward and reverse reaction rates will speed up equally, thereby allowing the system to reach equilibrium faster. https://courses.lumenlearning.com/boundless-chemistry/chapter/factors-that-affect-chemical-equilibrium/#:~:text=Le%20Chatelier's%20principle%20can%20be,heat%20produced%20in%20the%20system.

SMR 2.1.d: Demonstrate knowledge of nuclear forces that hold nuclei together and are responsible for nuclear processes (e.g., fission, fusion) and radioactivity (e.g., alpha, beta, and gamma decay).

An atom consists of an extremely small, positively charged nucleus surrounded by a cloud of negatively charged electrons. Nuclei consist of positively charged protons and electrically neutral neutrons held together by the so-called strong or nuclear force. This force is much stronger than the familiar electrostatic force that binds the electrons to the nucleus, but its range is limited to distances on the order of a few x10^-15 meters. The number of protons in the nucleus, Z, is called the atomic number. The atomic mass of the nucleus, A, is equal to Z + N. Materials that emit this kind of radiation are said to be radioactive and undergo radioactive decay. In 1899, Ernest Rutherford discovered that uranium compounds produce three different kinds of radiation. He separated the radiations according to their penetrating abilities and named them a alpha, B beta, and y gamma radiation, after the first three letters of the Greek alphabet. Rutherford later showed that an alpha particle is the nucleus of a He atom, 4He. Beta particles were later identified as high-speed electrons. Six millimeters of aluminum are needed to stop most B particles. Several millimeters of lead are needed to stop y rays, which proved to be high energy photons. Alpha particles and y rays are emitted with a specific energy that depends on the radioactive isotope. Beta particles, however, are emitted with a continuous range of energies from zero up to the maximum allowed for by the particular isotope. The emission of an a particle, or 4He nucleus, is a process called a decay. Since a particles contain protons and neutrons, they must come from the nucleus of an atom. The nucleus that results from a decay will have a mass and charge different from those of the original nucleus. A change in nuclear charge means that the element has been changed into a different element. Only through such radioactive decays or nuclear reactions can transmutation, the age-old dream of the alchemists, actually occur. Energy is released in the process of a decay. Careful measurements show that the sum of the masses of the daughter nuclear and the a particle is a bit less than the mass of the parent isotope. Beta particles are negatively charged electrons emitted by the nucleus. Gamma rays are a type of electromagnetic radiation that results from a redistribution of electric charge within a nucleus. A y ray is a high energy photon. The only thing which distinguishes a y ray from the visible photons emitted by a light bulb is its wavelength; the y ray's wavelength is much shorter. For complex nuclei, there are many different possible ways in which the neutrons and protons can be arranged within the nucleus. Gamma rays can be emitted when a nucleus undergoes a transition from one such configuration to another. The time required for half of the atoms in any given quantity of a radioactive isotope to decay is the half-life of that isotope. The half-life of 14C is 5730 years, thus it is useful for dating archaeological material. If nuclei come close enough together, they can interact with one another through the strong nuclear force, and reactions between the nuclei can occur. Two major classes of nuclear reactions are of importance: fusion and fission. Fusion is the nuclear process in which two light nuclei combine to form a single heavier nucleus. Such a large amount of energy is released in fusion reactions because when two light nuclei fuse, the sum of the masses of the product nuclei is less than the sum of the masses of the initial fusing nuclei. Once again, Einstein's equation, E=mc^2, explains that the mass that is lost is converted into energy carried away by the fusion products. Even though fusion is an energetically favorable reaction for light nuclei, it does not occur under standard conditions here on Earth because of the large energy investment that is required. Because the reacting nuclei are both positively charged, there is a large electrostatic repulsion between them as they come together. Only when they are squeezed very close to one another do they feel the strong nuclear force, which can overcome the electrostatic repulsion and cause them to fuse. Fusion reactions have been going on for billions of years in our universe. In fact, nuclear fusion reactions are responsible for the energy output of most stars, including our own Sun. Scientists on Earth have been able to produce fusion reactions for only about the last sixty years. At first, there were small scale studies in which only a few fusion reactions actually occurred. However, these first experiments later lead to the development of thermonuclear fusion weapons (hydrogen bombs). Fusion is the process that takes place in stars like our Sun. Whenever we feel the warmth of the Sun and see by its light, we are observing the products of fusion. Therefore, we can say that fusion is the basis for our life. When a star is formed, it initially consists of hydrogen and helium created in the Big Band, the process that created our universe. Fusion is a nuclear reaction in which nuclei combine to form a heavier nucleus. When a nucleus reaches mass sixty, no more fusion occurs in a star because it is energetically unfavorable to produce higher masses. The fusion chain cannot continue so its fuel is reduced. More peaceful uses of fusion are being researched today with the hope that soon we will be able to control fusion reactions to generate clean, inexpensive power. Fission is a nuclear process in which a heavy nucleus splits into two smaller nuclei. Fission reactions were used in atomic bombs and are still used in nuclear reactors. Fission reactions can produce any combination of lighter nuclei so long as the number of protons and neutrons in the products sum up to those in the initial fissioning nucleus. As with fusion, a great amount of energy can be released in fission because for heavy nuclei, the sum of the masses of the lighter product nuclei is less than the mass of the fissioning nucleus. Fission occurs because of the electrostatic repulsion created by the large number of positively charged protons contained in a heavy nucleus. So, once the larger nucleus can overcome the strong nuclear force which holds it together, it can fission. Fission can be seen as a "tug-of-war" between the strong attractive nuclear force and the repulsive electrostatic force. In fission reactions, electrostatic repulsion wins. Fission is a process that has been occurring in the universe for billions of years. As mentioned above, we have not only used fission to produce energy for nuclear bombs, but we also use fission peacefully every day to produce energy in nuclear power plants. Interestingly, although the first man-made nuclear reactor was produced only about fifty years ago, the Earth operated a natural fission reactor in a uranium deposit in West Africa about two billion years ago! https://www2.lbl.gov/abc/Basic.html

SMR 3.5.c: Demonstrate knowledge of major events that affected the evolution of life on Earth (e.g., climate changes, asteroid impacts).

In the course of its history, Earth must therefore have been impacted as heavily as the Moon. The difference is that, on Earth, these craters are destroyed by our active geology before they can accumulate. As plate tectonics constantly renews our crust, evidence of past cratering events is slowly erased. Only in the past few decades have geologists succeeded in identifying the eroded remnants of many impact craters. Even more recent is our realization that, over the history of Earth, these impacts have had an important influence on the evolution of life. If it had been larger or made of stronger material (such as metal), the Tunguska projectile would have penetrated all the way to the surface of Earth and exploded to form a crater. Instead, only the heat and shock of the atmospheric explosion reached the surface, but the devastation it left behind in Siberia bore witness to the power of such impacts. Imagine if the same rocky impactor had exploded over New York City in 1908; history books might today record it as one of the most deadly events in human history. The impact that produced Meteor Crater would have been dramatic indeed to any humans who witnessed it (from a safe distance) since the energy release was equivalent to a 10-megaton nuclear bomb. But such explosions are devastating only in their local areas; they have no global consequences. Much larger (and rarer) impacts, however, can disturb the ecological balance of the entire planet and thus influence the course of evolution. The best-documented large impact took place 65 million years ago, at the end of what is now called the Cretaceous period of geological history. This time in the history of life on Earth was marked by a mass extinction, in which more than half of the species on our planet died out. There are a dozen or more mass extinctions in the geological record, but this particular event (nicknamed the "great dying") has always intrigued paleontologists because it marks the end of the dinosaur age. For tens of millions of years these great creatures had flourished and dominated. Then, they suddenly disappeared (along with many other species), and thereafter mammals began the development and diversification that ultimately led to all of us. A catastrophe for one group of living things, however, may create opportunities for another group. Following each mass extinction, there is a sudden evolutionary burst as new species develop to fill the ecological niches opened by the event. Sixty-five million years ago, our ancestors, the mammals, began to thrive when so many other species died out. We are the lucky beneficiaries of this process. Impacts by comets and asteroids represent the only mechanisms we know of that could cause truly global catastrophes and seriously influence the evolution of life all over the planet. As paleontologist Stephen Jay Gould of Harvard noted, such a perspective changes fundamentally our view of biological evolution. The central issues for the survival of a species must now include more than just its success in competing with other species and adapting to slowly changing environments, as envisioned by Darwin's idea of natural selection. Also required is an ability to survive random global catastrophes due to impacts. Still earlier in its history, Earth was subject to even larger impacts from the leftover debris of planet formation. We know that the Moon was struck repeatedly by objects larger than 100 kilometers in diameter--1000 times more massive than the object that wiped out most terrestrial life 65 million years ago. Earth must have experienced similar large impacts during its first 700 million years of existence. Some of them were probably violent enough to strip the planet of most its atmosphere and to boil away its oceans. Such events would sterilize the planet, destroying any life that had begun. Life may have formed and been wiped out several times before our own microbial ancestors took hold sometime about 4 billion years ago. The fact that the oldest surviving microbes on Earth are thermophiles (adapted to very high temperatures) can also be explained by such large impacts. An impact that was just a bit too small to sterilize the planet would still have destroyed anything that lived in what we consider "normal" environments, and only the creatures adapted to high temperatures would survive. Thus, the oldest surviving terrestrial lifeforms are probably the remnants of a sort of evolutionary bottleneck caused by repeated large impacts early in the planet's history. The impacts by asteroids and comets that have had such a major influence on life are not necessarily a thing of the past. In the full scope of planetary history, 65 million years ago was just yesterday. Earth actually orbits the Sun within a sort of cosmic shooting gallery, and although major impacts are rare, they are by no means over. Humanity could suffer the same fate as the dinosaurs, or lose a city to the much more frequent impacts like the one over Tunguska, unless we figure out a way to predict the next big impact and to protect our planet. The fact that our solar system is home to some very large planets in outer orbits may be beneficial to us; the gravitational fields of those planets can be very effective at pulling in cosmic debris and shielding us from larger, more frequent impacts. Beginning in the 1990s, a few astronomers began to analyze the cosmic impact hazard and to persuade the government to support a search for potentially hazardous asteroids. Several small but sophisticated wide-field telescopes are now used for this search, which is called the NASA Spaceguard Survey. Already we know that there are currently no asteroids on a collision course with Earth that are as big (10-15 kilometers) as the one that killed the dinosaurs. The Spaceguard Survey now concentrates on finding smaller potential impactors. By 2015, the search had netted more than 15,000 near-Earth-asteroids, including most of those larger than 1 kilometer. None of those discovered so far poses any danger to us. Of course, we cannot make a similar statement about the asteroids that have not yet been discovered, but these will be found and evaluated one by one for their potential hazard. These asteroid surveys are one of the few really life-and-death projects carried out by astronomers, with a potential to help to save our planet from future major impacts. Earth, like the Moon and other planets, has been influenced by the impacts of cosmic debris, including such recent examples as Meteor Crater and the Tunguska explosion. Larger past impacts are implicated in some mass extinctions, including the large impact 65 million years ago at the end of the Cretaceous period that wiped out the dinosaurs and many other species. Today, astronomers are working to predict the next impact in advance, while other scientists are coming to grips with the effect of impacts on the evolution and diversity of life on Earth.

SMR 3.4.h: Solve problems from representations of monohybrid and dihybrid crosses.

The Punnett square is a valuable tool, but it's not ideal for every genetics problem. For instance, suppose you were asked to calculate the frequency of the recessive class not for an Aa x Aa cross, not for an AaBb x AaBb cross, but for an AaBbCcDdEe x AaBbCcDdEe cross. If you wanted to solve that question using a Punnett square, you could do it--but you'd need to complete a Punnett square with 1024 boxes. Probably not what you want to draw during an exam, or any other time, if you can help it. The five-gene problem above becomes less intimidating once you realize that a Punnett square is just a visual way of representing probability calculations. Although it's a great tool when you're working with one or two genes, it can become slow and cumbersome as the number goes up. At some point, it becomes quicker (and less error-prone) to simply do the probability calculations by themselves, without the visual representation of a clunky Punnett square. In all cases, the calculations and the square provide the same information, but by having both tools in your belt, you can be prepared to handle a wider range of problems in a more efficient way. In this article, we'll review some probability basics, including how to calculate the probability of two independent events both occurring (event X and event Y) or the probability of either of two mutually exclusive events occurring (event X or event Y). We'll then see how these calculations can be applied to genetics problems, and, in particular, how they can help you solve problems involving relatively large numbers of genes. Probabilities are mathematical measures of likelihood. In other words, they're a way of quantifying (giving a specific, numerical value to) how likely something is to happen. A probability of 1 for an event means that it is guaranteed to happen, while a probability of 0 for an event means that it is guaranteed not to happen. A simple example of probability is having a 1/2 chance of getting heads when you flip a coin. Probabilities can be either empirical, meaning that they are calculated from real-life observations, or theoretical, meaning that they are predicted using a set of rules or assumptions. - The empirical probability of an event is calculated by counting the number of times that event occurs and dividing it by the total number of times that event could have occurred. For instance, if the event you were looking for was a wrinkled pea seed, and you saw it 1,850 times out of the 7,324 total seeds you examined, the empirical probability of getting a wrinkled seed would be 1,850/7,324=0.253, or very close to 1 in 4 seeds. - The theoretical probability of an event is calculated based on information about the rules and circumstances that produce the event. It reflects the number of times an event is expected to occur relative to the number of times it could possibly occur. For instance, if you had a pea plant heterozygous for a seed shape gene (Rr) and let it self-fertilize, you could use the rules of probability and your knowledge of genetics to predict that 1 out of every 4 offspring would get two recessive alleles (rr) and appear wrinkled, corresponding to a 0.25 (1/4) probability. We'll talk more below about how to apply the rules of probability in this case. In general, the larger the number of data points that are used to calculate an empirical probability, such as shapes of individual pea seeds, the more closely it will approach the theoretical probability. One probability rule that's very useful in genetics is the product rule, which states that the probability of two (or more) independent events occurring together can be calculated by multiplying the individual probabilities of the events. For example, if you roll a six-sided die once, you have a 1/6 chance of getting a six. If you roll two dice at once, your chance of getting two sixes is: (probability of a six on die 1) x (probability of a six on die 2) = (1/6) x (1/6) = (1/36). In general, you can think of the product rule as the "and" rule: if both event X and event Y must happen in order for a certain outcome to occur, and if X and Y are independent of each other (don't affect each other's likelihood), then you can use the product rule to calculate the probability of the outcome by multiplying the probabilities of X and Y. We can use the product rule to predict frequencies of fertilization events. For instance, consider a cross between two heterozygous (Aa) individuals. What are the odds of getting an aa individual in the next generation? The only way to get an aa individual is if the mother contributes an a gamete and the family contributes an a gamete. Each parent has a 1/2 chance of making an a gamete. Thus, the chance of an aa offspring is: (probability of mother contributing a) x (probability of father contributing a) = (1/2) x (1/2) = (1/4). This is the same result you'd get with a Punnett square, and actually the same logical process as well--something that took me years to realize! The only difference is that, in the Punnett square, we'd do the calculation visually: we'd represent the 1/2 probability of an a gamete from each parent as one out of two columns (for the father) and one out of two rows (for the mother). The 1-square intersect of the column and the row (out of the 4 total squares of the table) represents the 1/4 chance of getting an a from both parents. In some genetics problems, you may need to calculate the probability that any one of several events will occur. In this case, you'll need to apply another rule of probability, the sum rule. According to the sum rule, the probability that any of several mutually exclusive events will occur is equal to the sum of the events' individual probabilities. For example, if you roll a six-sided die, you have a 1/6 chance of getting any given number, but you can only get one number per roll. You could never get both a one and a six at the same time; these outcomes are mutually exclusive. Thus, the chances of getting either a one or a six are: (probability of getting a 1) + (probability of getting a 6) = (1/6) + (1/6) = (1/3). You can think of the sum rule as the "or" rule: if an outcome requires that either event X or event Y occur, and if X and Y are mutually exclusive (if only one or the other can occur in a given case), then the probability of the outcome can be calculated by adding the probabilities of X and Y. As an example, let's use the sum rule to predict the fraction of offspring from an Aa x Aa cross that will have the dominant phenotype (AA or Aa genotype). In this cross, there are three events that can lead to a dominant phenotype: - Two A gametes meet (giving AA genotype), or - A gamete from Mom meets a gamete from Dad (giving Aa genotype), or - a gamete from Mom meets A gamete from Dad (giving Aa genotype) In any one fertilization event, only one of these three possibilities can occur (they are mutually exclusive). Since this is an "or" situation where the events are mutually exclusive we can apply the sum rule. Using the product rule as we did above, we can find that each individual event has a probability of 1/4. So, the probability of offspring with a dominant phenotype is: (probability of A from Mom and A from Dad) + (probability of A from Mom and a from Dad) + (probability of a from Mom and A from Dad) = (1/4) + (1/4) + (1/4) = (3/4). Once again, this is the same result we'd get with a Punnett square. One out of the four boxes of the Punnett square holds the dominant homozygote, AA. Two more boxes represent heterozygotes, one with a maternal A and a paternal a, the other with the opposite combination. Each box is 1 out of the 4 boxes in the whole Punnett square, and since the boxes don't overlap (they're mutually exclusive), we can add them up (1/4 + 1/4 + 1/4 = 3/4) to get the probability of offspring with the dominant phenotype. Product rule: For independent events X and Y, the probability (P) of them both occurring (X and Y) is P(X) x P(Y). Sum rule: For mutually exclusive events X and Y, the probability (P) that one will occur (X or Y) is P(X) + P(Y). Direct calculation of probabilities doesn't have much advantage over Punnett squares for single-gene inheritance scenarios. (In fact, if you prefer to learn visually, you may find direct calculation trickier rather than easier.) Where probabilities shine, though, is when you're looking at the behavior of two, or even more, genes. For instance, let's imagine that we breed two dogs with the genotype BbCc, where dominant allele B specifies black coat color (versus b, yellow coat color) and dominant allele C specifies straight fur (versus c, curly fur). Assuming that the two genes assort independently and are not sex-linked, how can we predict the number of BbCc puppies among the offspring? One approach is to draw a 16-square Punnett square. For a cross involving two genes, a Punnett square is still a good strategy. Alternatively, we can use a shortcut technique involving four-square Punnett squares and a little application of the product rule. In this technique, we break the overall question down into two smaller questions, each relating to a different genetic event: 1. What's the probability of getting a Bb genotype? 2. What's the probability of getting a Cc genotype? In order for a puppy to have a BbCc genotype, both of these events must take place: the puppy must receive Bb alleles, and it must receive Cc alleles. The two events are independent because the genes assort independently (don't affect one another's inheritance). So, once we calculate the probability of each genetic event, we can multiply these probabilities using the product rule to get the probability of the genotype of interest (BbCc). To calculate the probability of getting a Bb genotype, we can draw a 4-square Punnett square using the parents' alleles for the coat color gene only, as shown above. Using the Punnett square, you can see that the probability of the Bb genotype is 1/2. (Alternatively, we could have calculated the probability of Bb using the product rule for gamete contributions from the two parents and the sum rule for the two gamete contributions that give Bb). Using a similar Punnett square for the parents' fur texture alleles, the probability of getting a Cc genotype is also 1/2. To get the overall probability of the BbCc genotype, we can simply multiply the two probabilities, giving an overall probability of 1/4. The probability method is most powerful (and helpful) in cases involving a large number of genes. For instance, imagine a cross between two individuals with various alleles of four unlinked genes: AaBbCCdd x AabbCcDd. Suppose you wanted to figure out the probability of getting offspring with the dominant phenotype for all four traits. Fortunately, you can apply the exact same logic as in the case of the dihybrid crosses above. To have the dominant phenotype for all four traits, an organism must have: one or more copies of the dominant allele A and one or more copies of dominant allele B and one or more copies of the dominant allele C, and one or more copies of the dominant allele D. Since the genes are unlinked, these are four independent events, so we can calculate a probability for each and then multiply the probabilities to get the probability of the overall outcome. - The probability of getting one or more copies of the dominant A allele is 3/4. - The probability of getting one or more copies of the dominant B allele is 1/2. - The probability of getting one or more copies of the dominant C allele is 1. - The probability of getting one or more copies of the dominant D allele is 1/2, as for B. To get the overall probability of offspring with the dominant phenotype for all four genes, we can multiply the probabilities of the four independent events: (3/4) x (1/2) x (1) x (1/2) = (3/16).

SMR 3.5.a: Apply knowledge of anatomical, embryological, and genetic evidence of biological evolution and common ancestry and interpret branching diagrams (cladograms).

Evidence for evolution comes from many different areas of biology: - Anatomy. Species may share similar physical features because the feature was present in a common ancestor (homologous structures). - Molecular biology. DNA and the genetic code reflect the shared ancestry of life. DNA comparisons can show how related species are. - Biogeography. The global distribution of organisms and the unique features of island species reflect evolution and geological change. - Fossils. Fossils document the existence of now-extinct past species that are related to present-day species. - Direct observation. We can directly observe small-scale evolution in organisms with short lifecycles (e.g., pesticide-resistant insects). Evolution is a key unifying principle in biology. As Theodosius Dobzhansky once said, "Nothing in biology makes sense except in the light of evolution." But what, exactly, are the features of biology that make more sense through the lens of evolution? To put it another way, what are the indications or traces that show evolution has taken place in the past and is still happening today? Before we look at the evidence, let's make sure we are on the same page about what evolution is. Broadly speaking, evolution is a change in the genetic makeup (and often, the heritable features) of a population over time. Biologists sometimes define two types of evolution based on scale: - Macroevolution, which refers to large-scale changes that occur over extended time periods, such as the formation of new species and groups. - Microevolution, which refers to small-scale changes that affect just one or a few genes and happen in populations over shorter timescales. Microevolution and macroevolution aren't really two different processes. They're the same process--evolution--occurring on different timescales. Microevolutionary processes occurring over thousands or millions of years can add up to large-scale changes that define new species or groups. In this article, we'll examine the evidence for evolution on both macro and micro scales. First, we'll look at several types of evidence (including physical and molecular features, geographical information, and fossils) that provide evidence for, and can allow us to reconstruct macroevolutionary events. At the end of the article, we'll finish by seeing how microevolution can be directly observed, as in the emergence of pesticide-resistant insects. Darwin thought of evolution as "descent with modification," a process in which species change and give rise to new species over many generations. He proposed that the evolutionary history of life forms a branching tree with many levels, in which all species can be traced back to an ancient common ancestor. In this tree model, more closely related groups of species have more recent common ancestors, and each group will tend to share features that were present in its last common ancestor. We can use this idea to "work backwards" and figure out how organisms are related based on their shared features. If two or more species share a unique physical feature, such as a complex bone structure or a body plan, they may all have inherited this feature from a common ancestor. Physical features shared due to evolutionary history (a common ancestor) are said to be homologous. To give one classic example, the forelimbs of whales, humans, birds, and dogs look pretty different on the outside. That's because they're adapted to function in different environments. However, if you look at the bone structure of the forelimbs, you'll find that the pattern of bones is very similar across species. It's unlikely that such similar structures would have evolved independently in each species, and more likely that the basic layout of bones was already present in a common ancestor of whales, humans, dogs, and birds. Some homologous structures can be seen only in embryos. For instance, all vertebrate embryos (including humans) have gill slits and a tail during early development. The developmental patterns of these species become more different later on (which is why your embryonic tail is now your tailbone, and your gill slits have turned into your jaw and inner ear). Homologous embryonic structures reflect that the developmental programs of vertebrates are variations on a similar plan that existed in their last common ancestor. Sometimes, organisms have structures that are homologous to important structures in other organisms but that have lost their major ancestral function. These structures, which are often reduced in size, are known as vestigial structures. Examples of vestigial structures include the tailbone of humans (a vestigial tail), the hind leg bones of whales, and the underdeveloped legs found in some snakes. To make things a little more interesting and complicated, not all physical features that look alike are marks of common ancestry. Instead, some physical similarities are analogous: they evolved independently in different organisms because the organisms lived in similar environments or experienced similar selective pressures. This process is called convergent evolution. (To converge means to come together, like two lines meeting at a point.) For example, two distantly related species that live in the Arctic, the arctic fox and the ptarmigan (a bird), both undergo seasonal changes of color from dark to snowy white. This shared feature doesn't reflect common ancestry--i.e., it's unlikely that the last common ancestor of the fox and ptarmigan changed color with the seasons. Instead, this feature was favored separately in both species due to similar selective pressures. That is, the genetically determined ability to switch to light coloration in winter helped both foxes and ptarmigans survive and reproduce in a place with snowy winters and sharp-eyed predators. In general, biologists don't draw conclusions about how species are related on the basis of any single feature they think is homologous. Instead, they study a large collection of features (often, both physical features and DNA sequences) and draw conclusions about relatedness based on these features as a group. We will explore this idea further when we examine phylogenetic trees. Like structural homologies, similarities between biological molecules can reflect shared evolutionary ancestry. At the most basic level, all living organisms share: - The same genetic material (DNA) - The same, or highly similar, genetic codes - The same basic process of gene expression (transcription and translation) - The same molecular building blocks, such as amino acids These shared features suggest that all living things are descended from a common ancestor, and that this ancestor had DNA as its genetic material, used the genetic code, and expressed its genes by transcription and translation. Present-day organisms all share these features because they were "inherited" from the ancestor (and because any big changes in this basic machinery would have broken the basic functionality of cells). Although they're great for establishing the common origins of life, features like having DNA or carrying out transcription and translation are not so useful for figuring out how related particular organisms are. If we want to determine which organisms in a group are most closely related, we need to use different types of molecular features, such as the nucleotide sequences of genes. Biologists often compare the sequences of related genes found in different species (often called homologous or orthologous genes) to figure out how those species are evolutionarily related to one another. The basic idea behind this approach is that two species have the "same" gene because they inherited it from a common ancestor. For instance, humans, cows, chickens, and chimpanzees all have a gene that encodes the hormone insulin, because this gene was already present in their last common ancestor. In general, the more DNA differences in homologous genes (or amino acid differences in the proteins they encode) between two species, the more distantly the species are related. For instance, human and chimpanzee insulin proteins are much more similar (about 98% identical) than human and chicken insulin proteins (about 64% identical), reflecting that humans and chimpanzees are more closely related than humans and chickens. The geographic distribution of organisms on Earth follows patterns that are best explained by evolution, in combination with the movement of tectonic plates over geological time. For example, broad groupings of organisms that had already evolved before the breakup of the supercontinent Pangaea (about 200 million years ago) tend to be distributed worldwide. In contrast, broad groupings that evolved after the breakup tend to appear uniquely in smaller regions of Earth. For instance, there are unique groups of plants and animals on northern and southern continents that can be traced to the split of Pangaea into two supercontinents (Laurasia in the north, and Gondwana in the south). The evolution of unique species on islands is another example of how evolution and geography intersect. For instance, most of the mammal species in Australia are marsupials (carry young in a pouch), while most mammal species elsewhere in the world are placental (nourish young through a placenta). Australia's marsupial species are very diverse and fill a wide range of ecological roles. Because Australia was isolated by water for millions of years, these species were able to evolve without competition from (or exchange with) mammal species elsewhere in the world. The marsupials of Australia, Darwin's finches in the Galápagos, and many species on the Hawaiian Islands are unique to their island settings, but have distant relationships to ancestral species on mainlands. This combination of features reflects the processes by which island species evolve. They often arise from mainland ancestors--for example, when a landmass breaks off or a few individuals are blown off course during a storm--and diverge (become increasingly different) as they adapt in isolation to the island environment. Fossils are the preserved remains of previously living organisms or their traces, dating from the distant past. The fossil record is not, alas, complete or unbroken: most organisms never fossilize, and even the organisms that do fossilize are rarely found by humans. Nonetheless, the fossils that humans have collected offer unique insights into evolution over long timescales. How can the age of fossils be determined? First, fossils are often contained in rocks that build up in layers called strata. The strata provide a sort of timeline, with layers near the top being newer and layers near the bottom being older. Fossils found in different strata at the same site can be ordered by their positions, and "reference" strata with unique features can be used to compare the ages of fossils across locations. In addition, scientists can roughly date fossils using radiometric dating, a process that measures the radioactive decay of certain elements. Fossils document the existence of now-extinct species, showing that different organisms have lived on Earth during different periods of the planet's history. They can also help scientists reconstruct the evolutionary histories of present-day species. For instance, some of the best-studied fossils are of the horse lineage. Using these fossils, scientists have been able to reconstruct a large, branching "family tree" for horses and their now-extinct relatives. Changes in the lineage leading to modern-day horses, such as the reduction of toed feet to hooves, may reflect adaptation to changes in the environment. In some cases, the evidence for evolution is that we can see it taking place around us! Important modern-day examples of evolution include the emergence of drug-resistant bacteria and pesticide-resistant insects. For example, in the 1950s, there was a worldwide effort to eradicate malaria by eliminating its carriers (certain types of mosquitos). The pesticide DDT was sprayed broadly in areas where the mosquitoes lived, and at first, the DDT was highly effective at killing the mosquitos. However, over time, the DDT became less and less effective, and more and more mosquitoes survived. This was because the mosquito population evolved resistance to the pesticide. Emergence of DDT resistance is an example of evolution by natural selection. How would natural selection have worked in this case? 1. Before DDT was applied, a tiny fraction of mosquitos in the population would have had naturally occurring gene versions (alleles) that made them resistant to DDT. These versions would have appeared through random mutation, or changes in DNA sequence. Without DDT around, the resistant alleles would not have helped mosquitoes survive or reproduce (and might even have been harmful), so they would have remained rare. 2. When DDT spraying began, most of the mosquitos would have been killed by the pesticide. Which mosquitos would have survived? For the most part, only the rare individuals that happened to have DDT resistance alleles (and thus survived being sprayed with DDT). These surviving mosquitoes would have been able to reproduce and leave offspring. 3. Over generations, more and more DDT-resistant mosquitoes would have been born into the population. That's because resistant parents would have been consistently more likely to survive and reproduce than non-resistant parents, and would have passed their DDT resistance alleles (and thus, the capacity to survive DDT) on to their offspring. Eventually, the mosquito populations would have bounced back to high numbers, but would have been composed largely of DDT-resistant individuals. In parts of the world where DDT has been used extensively in the past, many of the mosquitoes are now resistant. DDT can no longer be used to control the mosquito populations (and reduce malaria) in these regions. Why are mosquito populations able to evolve rapid resistance to DDT? Two important factors are large population size (making it more likely that some individuals in the population will, by random chance, have mutations that provide resistance) and short lifecycle. Bacteria and viruses, which have even larger population sizes and shorter lifecycles, can evolve resistance to drugs very rapidly, as in antibiotic-resistant bacteria and drug-resistant HIV. A phylogeny, or evolutionary tree, represents the evolutionary relationships among a set of organisms or groups of organisms, called taxa (singular: taxon). The tips of the tree represent groups of descendent taxa (often species) and the nodes on the tree represent the common ancestors of those descendants. Two descendents that split from the same node are called sister groups. In the tree below, species A & B are sister groups--they are each other's closest relatives. Many phylogenies also include an outgroup — a taxon outside the group of interest. All the members of the group of interest are more closely related to each other than they are to the outgroup. Hence, the outgroup stems from the base of the tree. An outgroup can give you a sense of where on the bigger tree of life the main group of organisms falls. It is also useful when constructing evolutionary trees. Evolutionary trees depict clades. A clade is a group of organisms that includes an ancestor and all descendants of that ancestor. You can think of a clade as a branch on the tree of life.

SMR 3.3.a: Demonstrate knowledge of the abiotic and biotic factors in an ecosystem and their relationship to the growth of individual organisms.

Abiotic factors refer to non-living physical and chemical elements in the ecosystem. Abiotic resources are usually obtained from the lithosphere, atmosphere, and hydrosphere. Examples of abiotic factors are water, air, soil, sunlight, and minerals. Biotic factors are living or once-living organisms in the ecosystem. These are obtained from the biosphere and are capable of reproduction. Examples of biotic factors are animals, plants, fungi, and similar organisms. Abiotic: Introduction - In ecology and biology, abiotic components are non-living chemical and physical factors in the environment which affect ecosystems. Examples - Water, light, wind, soil, humidity, minerals, gases. Factors - Affect the ability of organisms to survive, reproduce; help determine types and numbers of organisms able to exist in environment; limiting factors restrict growth. Affects - Individual of a species, population, community, ecosystem, biome, biosphere. Biotic: Introduction - Biotic describes a living component of an ecosystem; for example organisms, such as plants and animals. Examples - All living things--autotrophs and heterotrophs--plants, animals, fungi, bacteria. Factors - Living things that directly or indirectly affect organisms in the environment; organisms, interactions, waste; parasitism, disease, predation. Affects - Individual of a species, population, community, ecosystem, biome, biosphere. Biotic components are living organisms in an ecosystem. A biotic factor is a living organism that affects another organism in its ecosystem. Examples include plants and animals that the organism consumes as food, and animals that consume the organism. The scope of abiotic and biotic factors spans across the entire biosphere, or global sum of all ecosystems. Such factors can have relevance for an individual within a species, its community, or an entire population. For example, disease is a biotic factor affecting the survival of an individual and its community. Temperature is an abiotic factor with the same relevance. Some factors have greater relevance for an entire ecosystem. Abiotic and biotic factors combine to create a system or, more precisely, an ecosystem, meaning a community of living and nonliving things considered as a unit. In this case, abiotic factors span as far as the pH of the soil and water, types of nutrients available and even the length of the day. Biotic factors such as the presence of autotrophs or self-nourishing organisms such as plants, and the diversity of consumers also affect an entire ecosystem. Abiotic factors affect the ability of organisms to survive and reproduce. Abiotic limiting factors resist the growth of populations. They help determine the types and numbers of organisms able to exist within an environment. Biotic factors are living things that directly or indirectly affect organisms within an environment. This includes the organisms themselves, other organisms, interactions between living organisms and even their waste. Other biotic factors include parasitism, disease, and predation (the act of one animal eating another). The significance of abiotic and biotic factors come in their interactions with each other. For a community or an ecosystem to survive, the correct interactions need to be in place. A simple example would be of abiotic interaction in plants. Water, sunlight, and carbon dioxide are necessary for plants to grow. The biotic interaction is that plants use water, sunlight, and carbon dioxide to create their own nourishment through a process called photosynthesis. On a larger scale, abiotic interactions refer to patterns such as climate and seasonality. Factors such as temperature, humidity, and the presence or absence of seasons affect the ecosystem. For instance, some ecosystems experience cold winters with a lot of snow. An animal such as a fox within this ecosystem adapts to these abiotic factors by growing a thick, white-colored coat in the winter. Decomposers such as bacteria and fungi are examples of biotic interactions on such a scale. Decomposers function by breaking down dead organisms. This process returns the basic components of the organisms to the soil, allowing them to be reused within that ecosystem.

SMR 2.2.b: Apply knowledge of the principles of conversation of matter to chemical reactions, including balancing chemical equations.

In chemical changes, new substances are formed when a rearrangement of the atoms within the substance has occurred. Thus, when new substances are formed, a chemical change has occurred, and a chemical reaction has taken place. It is important to note that the total number of atoms involved in a chemical reaction are not reduced or increased. No new atoms are created or destroyed--only rearranged. For a change to be considered a chemical change, chemical bonds must be altered in some way. A chemical bond is the physical property responsible for the intermolecular and intramolecular attractive interactions between atoms that confer stability to chemical compounds. To form or break a chemical bond, valence electrons are involved in the chemical reaction. As we discussed in "Lesson 5 on Thermodynamics", chemical changes are a result of The Law of Conservation of Matter, which states that matter can neither be created nor destroyed. This is one of the fundamental laws of nature, although seems to contradict what we observe on a daily basis. The observations that water seems to "disappear" in a boiling teapot, or that salt "disappears" when it is dissolved in a glass of water, are really conservation of matter. These and other classroom experiments can explore various manifestations of the law. They build conceptually on the particle model of matter to explain physical changes. When there is change in the physical nature or physical appearance of a substance (such as the freezing of water), and there is no change in its chemical composition, this is known in chemistry as a physical change. When there is a change in the chemical composition of a substance (such as the burning of wood), this would constitute a chemical change. When new substances are formed, a chemical change has occurred and a chemical reaction has taken place. A chemical reaction equation is a symbolic representation of a chemical reaction. The reactant substances are represented on the left side of the equation, and the product substances are represented on the right side with an arrow in between the two, representing which direction the reaction is proceeding. The number of atoms for each element does not change in a chemical reaction. Each side of the equation represents an equal number of atoms of any particular element. The equation must be balanced. It is here where the Law of Conservation of Mass/Matter can be applied; where matter is neither created nor destroyed, yet can change from one form to another. The process of balancing chemical equations involves three steps: interpreting a chemical formula, determining whether or not a chemical equation is balanced, and balancing the chemical equation. The subscript number tells us the number of atoms for a particular element: e.g., in (NH_4)_2S, nitrogen has 1 atom, hydrogen has 4 atoms, and sulfur has 1 atom. The subscript number outside the parenthesis is for all the elements in the parenthesis: e.g., in (NH_4)_2, the subscript 2 is for both N and H. To calculate the total number of atoms, multiply the two subscript numbers (e.g., for N 1 x 2 =2 and for H 4 x 2 = 8). Interpreting the chemical formula is only the first step. Determining whether an equation is balanced, and balancing the equation (if necessary), are the next steps. https://uciunex.instructure.com/courses/9475/pages/refresher-chemical-changes?module_item_id=480780

SMR 3.2.b: Compare single-celled and multicellular organisms, including the role of cell differentiation in the development of multicellular organisms.

Key points: - A multicellular organism develops from a single cell (the zygote) into a collection of many different cell types, organized into tissues and organs. - Development involves cell division, body axis formation, tissue and organ development, and cell differentiation (gaining a final cell type identity). - During development, cells use both intrinsic or inherited, information and extrinsic signals from neighbors to "decide on" their behavior and identity. - Cells usually become more and more restricted in their development potential (the cell types they can produce) as development progresses. Organisms are made up of a single cell or multiple cells. Most single-celled organisms are found in the Kingdom Monera and Protista. Most multi-celled organisms are found in the Kingdoms Fungi, Plantae, and Animalia. Single-celled organisms: Tiny and microscopic. They may have a nucleus or chloroplast or other cell structures. They can be plant-like, animal-like, or bacteria-like. They reproduce either sexually or asexually. They live either alone or in colonies. Some are able to move around and some do not. They can get food from other organisms or make their own food. Single-celled organisms were the first living organisms to develop on Earth approximately 3.5 billion years ago. Multicellular organisms: They may have a nucleus, chloroplast, and mitochondria. They may be a plant, animal, or fungi. they reproduce either sexually or asexually. They live alone or in groups. Multicellular organisms evolved independently numerous times. The Cambrian Era saw the widespread arrival of multicellular organisms. Multicellular life evolved from single cells in two stages. First, single-cells evolved the ability to form loose cooperative communities called biofilms. The earliest colony of bacteria was the cyanobacteria that evolved more than 3 billion years ago (bya). Present-day biofilms include slime, mold, dental plaque, films on rocks and in streams. Eventually, one true multicellular organism formed, known as a metazoan. Unlike the cells in biofilms, all cells in a metazoan originally shared the same DNA. As the organism develops, the cell's genetic programs direct them to permanently silence much of their DNA, thereby becoming specialized. Single-celled organisms function very well as individuals. However, some of that individuality had to be given up when cells combined together as a single multicellular organism. For example, in order to work together as a coherent, multicellular body, individual cells cannot simply dive into cell division. Otherwise, cancer forms. Cell specialization through differentiation: Differentiation is intricately regulated by gene expresses which switch specific genes on and off at specific times. Differentiation can involve changes in numerous aspects of cell physiology (size, shape, activity, responsiveness). There are different types of cells that go through differentiation. Pluripotent cells: Cells that have the potential to develop into most types of specialized cells, not restricted to a specific system. For example, embryonic cells are pluripotent. Totipotent cells: Cells that are able to regenerate into a whole new individual. For example, zygote and spore cells are totipotent. Multipotent progenitor cells: Cells that have the same basic features as stem cells. They differentiate into other different types of cells, but into closely related families of cells. Blood stem cells are able to differentiate into different kinds of blood cells, but not into other cells, such as brain cells.

SMR 2.5.g: Demonstrate knowledge of the energy changes that accompany changes in states of matter.

When there is a change only in the physical nature or physical appearance of a substance (such as the freezing of water) and there is no change in chemical composition, this is known in chemistry as a physical change. When there is a change in the chemical composition of a substance (such as the burning of wood), this would constitute a chemical change. New substances are not created during a physical change. Physical changes result in the same substance with a change only in the form or shape of that substance. A physical change can result in a substance changing from a gas to liquid, a liquid to a gas, or a liquid to a solid, and so on. Chemical changes, however, result in the formation of new substances. For instance, chemical reactions, such as those found in the chloroplast of plant cells, cause the formation of sugar by the reaction of water and carbon dioxide. Other examples of chemical changes: - Iron reacting with oxygen in the air to create rust. - An anti-acid tablet neutralizing excess stomach acid. - Baking cookies. https://uciunex.instructure.com/courses/9475/pages/refresher-physical-vs-chemical-changes?module_item_id=480736

SMR 3.1.f: Demonstrate knowledge of the process and significance of protein synthesis.

- RNA (ribonucleic acid): Single-stranded nucleic acid that carries out the instructions coded in DNA. - Central dogma of biology: The process by which the information in genes flows into proteins: DNA --> RNA --> protein. - Polypeptide: A chain of amino acids. - Codon: A sequence of three nucleotides that corresponds with a specific amino acid or start/stop signal during translation. - Transcription: Process during which a DNA sequence of a gene is copied to make an RNA molecule. - Translation: Process during which an mRNA molecule is used to assemble amino acids into polypeptide chains. - Mutation: A change in a genetic sequence. DNA alone cannot account for the expression of genes. RNA is needed to help carry out the instructions in DNA. Like DNA, RNA is made up of nucleotide consisting of a 5-carbon sugar ribose, a phosphate group, and a nitrogenous base. However, there are three main differences between DNA and RNA: 1. RNA uses the sugar ribose instead of deoxyribose. 2. RNA is generally single-stranded instead of double-stranded. 3. RNA contains uracil in place of thymine. These differences help enzymes in the cell distinguish DNA from RNA. RNA (ribonucleic acid) contains nucleotides cytosine (C), guanine (g), adenine (a) and uracil (u). DNA (deoxyribonucleic acid) contains nucleotides cytosine (c), guanine (g), adenine (a), and thymine (t). A base pair is when the double-stranded DNA connects together using two connecting nucleotides. Adenine pairs with thymine and cytosine pairs with guanine. The "backbone" of DNA is deoxyribose-phosphate and the the "backbone" of RNA is ribose-phosphate. Messenger RNA (mRNA): Carries information from DNA in the nucleus to ribosomes in the cytoplasm. Ribosomal RNA (rRNA): Structural component of ribosomes. Transfer RNA (tRNA): Carries amino acids to the ribosome during translation to help build an amino acid chain. A gene that encodes a polypeptide is expressed in two steps. In this process, information flows from DNA --> RNA --> protein, a directional relationship known as the central dogma of molecular biology. The first step in decoding genetic messages is transcription, during which a nucleotide sequence is copied from DNA to RNA. The next step is to join amino acids together to form a protein. The order in which amino acids are joined together determine the shape, properties, and function of a protein. The four bases of RNA form a language with just four nucleotide bases: adenine (A), cytosine (C), guanine (G), and uracil (U). The genetic code is read in three-base words called codons. Each codon corresponds to a single amino acid (or signals the starting and stopping points of a sequence). In transcription, a DNA sequence is rewritten, or transcribed, into a similar RNA "alphabet." In eukaryotes, the RNA molecule must undergo processing to become a mature messenger RNA (mRNA). In translation, the sequence of the mRNA is decoded to specify the amino acid sequence of a polypeptide. The name translation reflects that the nucleotide sequence of the mRNA sequence must be translated into the completely different "language" of amino acids. Sometimes cells make mistakes in copying their genetic information, causing mutations. Mutations can be irrelevant, or they can affect the way proteins are made and genes are expressed. A substitution changes a single base pair by replacing one base for another. There are three kinds of substitution mutations: 1. Silent mutations do not affect the sequence of amino acids during translation. 2. Nonsense mutations result in a stop codon where an amino acid should be, causing translation to stop prematurely. 3. Missense mutations change the amino acid specified by a codon. An insertion occurs when one or more bases are added to a DNA sequence. A deletion occurs when one or more bases are removed from a DNA sequence. Because the genetic code is read in codons (three bases at a time), inserting or deleting bases may change the "reading fame" of the sequence. These types of mutations are called frameshift mutations. A frameshift mutation changes how nucleotides are interpreted an codons beyond the point of the mutation, and this, in turn, may change the amino acid sequence. - Amino acids are not made during protein synthesis. Some students think that the purpose of protein synthesis is to create amino acids. However, amino acids are not being made during translation, they are being used as building blocks to make proteins. - Mutations do not always have drastic or negative effects. Often people hear the term "mutation" in the media and understand it to mean that a person will have a disease or disfigurement. Mutations are the source of genetic variety, so although some mutations are harmful, most are unnoticeable, and many are even good! - Insertions and deletions that are multiples of three nucleotides will not cause frameshift mutations. Rather, one or more amino acids will just be added to or deleted from the protein. Insertions and deletions that are not multiples of three nucleotides, however, can dramatically alter the amino acid sequence of the protein. https://www.khanacademy.org/science/high-school-biology/hs-molecular-genetics/hs-rna-and-protein-synthesis/a/hs-rna-and-protein-synthesis-review

SMR 3.2.e: Demonstrate knowledge of feedback mechanisms responsible for maintaining homeostasis in animals, including humans, and plants, including the anatomical structures and systems involved in regulating internal conditions.

Animal organs and organ systems constantly adjust to internal and external changes through a process called homeostasis ("steady state"). These changes might be in the level of glucose or calcium in blood or in external temperatures. Homeostasis means to maintain dynamic equilibrium in the body. It is dynamic because it is constantly adjusting to the changes that the body's systems encounter. It is an equilibrium because body functions are kept within specific ranges. Even an animal that is apparently inactive is maintaining this homeostatic equilibrium. The goal of homeostasis is the maintenance of equilibrium around a point or value called a set point. While there are normal fluctuations from the set point, the body's systems will usually attempt to go back to this point. A change in the internal or external environment is called a stimulus and is detected by a receptor; the response of the system is to adjust the deviation parameter toward the set point. For instance, if the body becomes too warm, adjustments are made to cool the animal. If the blood's glucose rises after a meal, adjustments are made to lower the blood glucose level by getting the nutrient into tissues that need it or to store it for later use. When a change occurs in an animal's environment, an adjustment must be made. The receptor senses the change in the environment, then sends a signal to the control center (in most cases, the brain) which in turn generates a response that is signaled to an effector. The effector is a muscle (that contracts or relaxes) or a gland that secretes. Homeostasis is maintained by negative feedback loops. Positive feedback loops actually push the organism further out of homeostasis, but may be necessary for life to occur. Homeostasis is controlled by the nervous and endocrine system of mammals. Any homeostatic process that changes the direction of the stimulus is a negative feedback loop. It may either increase or decrease the stimulus, but the stimulus is not allowed to continue as it did before the receptor sensed it. In other words, if a level is too high, the body does something to bring it down, and conversely, if a level is too low, the body does something to make it go up. Hence the term negative feedback. Recall animal maintenance of blood glucose levels: When an animal has eaten, blood glucose levels rise. This is sensed by the nervous system. Specialized cells in the pancreas sense this, and the hormone insulin is released by the endocrine system. Insulin causes blood glucose levels to decrease, as would be expected in a negative feedback system. However, if an animal has not eaten and blood glucose levels decrease, this is sensed in another group of cells in the pancreas, and the hormone glucagon is released causing glucose levels to increase. Negative feedback loops are the predominant mechanism used in homeostasis. A positive feedback loop maintains the direction of the stimulus, possibly accelerating it. Few examples of positive feedback loops exist in animal bodies, but one is found in the cascade of chemical reactions that result in blood clotting, or coagulation. As one clotting factor is activated, it activates the next factor in sequence until a fibrin clot is achieved. The direction is maintained, not changed, so this is positive feedback. Another example of positive feedback is uterine contractions during childbirth. The hormone oxytocin, made by the endocrine system, stimulates the contraction of the uterus. This produces pain sensed by the nervous system. Instead of lowering the oxytocin and causing the pain to subside, more oxytocin is produced until the contractions are powerful enough to produce childbirth. It is possible to adjust a system's set point. When this happens, the feedback loop works to maintain the new setting. An example of this is blood pressure: over time, the normal or set point for blood pressure can increase as a result of continued increases in blood pressure. The body no longer recognizes the elevation as abnormal and no attempt is made to return to the lower set point. The result is the maintenance of an elevated blood pressure that can have harmful effects on the body. Medication can lower blood pressure and lower the set point in the system to a more healthy level. This is called a process of alteration of the set point in a feedback loop. Changes can be made in a group of body organ systems in order to maintain a set point in another system. This is called acclimatization. This occurs, for instance, when an animal migrates to a higher altitude than it is accustomed to. In order to adjust to the lower oxygen levels at the new altitude, the body increases the number of red blood cells circulating in the blood to ensure adequate oxygen delivery to the tissues. Another example of acclimatization is animals that have seasonal changes in their coats: a heavier coat in the winter ensures adequate heat retention, and a light coat in summer assists in keeping body temperature from rising to harmful levels. Body temperature affects body activities. Generally, as body temperature rises, enzyme activity rises as well. For every ten degree centigrade rise in temperature, enzyme activity doubles, up to a point. Body proteins, including enzymes, begin to denature and lose their function with high heat (around 50 degrees C for mammals). Enzyme activity will decrease by half for every ten degree centigrade drop in temperature, to the point of freezing, with a few exceptions. Some fish can withstand freezing solid and return to normal with thawing. Animals can be divided into two groups: some maintain a constant body temperature in the face of differing environmental temperatures, while others have a body temperature that is the same as their environment and thus varies with the environment. Animals that do not control their body temperature are ectotherms. This group has been called cold-blooded, but the term may not apply to an animal in the desert with a very warm body temperature. In contrast to ectotherms, which rely on external temperatures to set their body temperatures, poikilotherms are animals with constantly varying internal temperatures. An animal that maintains a constant body temperature in the face of environmental changes is called a homeotherm. Endotherms are animals that rely on internal sources for body temperature but which can exhibit extremes in temperature. These animals are able to maintain a level of activity at cooler temperature, which an ectotherm cannot due to differing enzyme levels of activity. Heat can be exchanged between an animal and its environment through four mechanisms: radiation, evaporation, convection, and conduction. Radiation is the emission of electromagnetic "heat" waves. Heat comes from the sun in this manner and radiates from dry skin the same way. Heat can be removed with liquid from a surface during evaporation. This occurs when a mammal sweats. Convection currents of air remove heat from the surface of dry skin as the air passes over it. Heat will be conducted from one surface to another during direct contact with the surfaces, such as an animal resting on a warm rock. Animals conserve or dissipate heat in a variety of ways. In certain climates, endothermic animals have some form of insulation, such as fur, fat, feathers, or some combination thereof. Animals with thick fur or feathers create an insulating layer of air between their skin and internal organs. Polar bears and seals live and swim in a subfreezing environment and yet maintain a constant, warm, body temperature. The arctic fox, for example, uses its fluffy tail as extra insulation when it curls up to sleep in cold weather. Mammals have a residual effect from shivering and increased muscle activity: arrector pili muscles cause "goose bumps" causing small hairs to stand up when the individual is cold; this has the intended effect of increasing body temperature. Mammals use layers of fat to achieve the same end. Loss of significant amounts of body fat will compromise an individual's ability to conserve heat. Endotherms use their circulatory systems to help maintain body temperature. Vasodilation brings more blood and heat to the body surface, facilitating radiation and evaporative heat loss, which helps to cool the body. Vasoconstriction reduces blood flow in peripheral blood vessels, forcing blood toward the core and the vital organs found there, and conserving heat. Some animals have adaptions to their circulatory system that enable them to transfer heat from arteries to veins, warming blood returning to the heart. This is called a countercurrent heat exchange; it prevents the cold venous blood from cooling the heart and other internal organs. This adaption can be shut down in some animals to prevent overheating the internal organs. The countercurrent adaption is found in many animals, including dolphins, sharks, bony fish, bees, and hummingbirds. In contrast, similar adaptations can help cool endotherms when needed, such as dolphin flukes and elephant ears. Some ectothermic animals use changes in their behavior to help regulate body temperature. For example, a desert ectothermic animal may simply seek cooler areas during the hottest part of the day in the desert to keep from getting too warm. The same animals may climb onto rocks to capture heat during a cold desert night. Some animals seek water to aid evaporation in cooling them, as seen with reptiles. Other ectotherms use group activity such as the activity of bees to warm a hive to survive winter. Many animals, especially mammals, use metabolic waste heat as a heat source. When muscles are contracted, most of the energy from the ATP used in muscle actions is wasted energy that translates into heat. Severe cold elicits a shivering reflex that generates heat for the body. Many species also have a type of adipose tissue called brown fat that specializes in generating heat. Additionally, regulation of body temperature can be done with respect to relative differences between internal and external temperatures. Homeotherms maintain a relatively constant body temperature as external temperature varies (homeo = 'same'), whereas Heterotherms usually maintain a relatively constant body temperature but have specific periods where body temperature fluctuates with environmental temperature (e.g., during hibernation). Poikilotherms, in contrast, have body temperature fluctuations which change with environmental temperature. Plants encounter challenging environmental conditions during extreme drought or flooding. Drought is particularly challenging for a plant because the plant requires water to carry out photosynthesis, but photosynthesis results in water lost due to evaporation. This is where the whole stomata staying open thing come in. CAM plants can later the timing of their Calvin cycle processes to avoid/minimize O2 use and water loss.

SMR 2.1.f: Apply knowledge of physical changes of matter and physical properties of matter.

All substances have a unique set of physical properties. This allows us to distinguish one substance from another by their distinctive characteristics. The physical properties of substances can be observed or measured without changing the identity and composition of the substance. These measurable properties include: structure, melting point, boiling point, hardness, density, color, freezing point, thermal and electrical conductivity. The physical state of a substance--i.e., liquid, solid, or gas--determines its physical properties and structure. The physical structures of substances are the result of intermolecular forces, the forces that exist between molecules, found within various substances. By understanding the nature and varying degrees of strength of intermolecular forces, scientists can relate the composition and structure of molecules to their physical properties. The physical properties of gaseous substances can be determined through kinetic-molecular theory. According to this theory, the energy of the molecules within gaseous substances is much larger than the average energy of the attractions between them. This results in an overall weakening of strong attractive forces between molecules in a gaseous substance, which allows the gas to expand and fill its container. Liquids exhibit stronger intermolecular forces, which allow molecules within a liquid to stay closer to one another. As a result, liquids are much denser and far less compressible than gaseous substances. However, the attractive forces within liquids are not strong enough to keep molecules from "gliding" past one another. As a result, liquids can be poured, and they will take on the shape of their containers. Intermolecular attractive forces found within solid substances are much stronger than those found in liquids or gases. As a result, the strong attractive forces within solid substances hold and "lock" the molecules in place. As in liquids, solids are not very compressible since the molecules have little or minute amounts of space between them. Throughout nature, molecules in most solids take up positions in a highly organized and regular pattern. The strength of intermolecular forces within substances varies. Numerous properties of liquids, including their boiling points, depend upon the strengths of the intermolecular forces. The boiling point of a liquid refers to the energy required to break the bonds of the attractive forces between the molecules, so that the molecules can separate and form a vapor. The stronger the attractive forces are within a liquid, the higher the temperature at which a liquid boils and thus the more energy input required by the liquid. The opposite is true for the freezing point of a liquid. This is also the case with the melting point of solids. As the intermolecular attractive forces between the molecules within a solid increase, the melting point temperature also increases. The hardness of solid substances can be measured, and is used as a type of physical property to distinguish one solid substance from another. Hardness refers to the physical characteristic of a solid substance expressing its resistance to permanent deformation, depending upon the strength of the intermolecular forces within that substance. The color of a substance is easy to observe. It can be determined by the particular wavelength a substance absorbs and reflects (e.g., black absorbs all the wavelengths of light and white reflects all the wavelengths of light). The density of a substance such as a liquid, solid, or a gas can also be measured. In order to calculate density, one much measure the mass of a substance and divide it by the measured volume of the substance. The density of a gas can change depending upon the container it is in, since decreasing the volume of a gas will increase its density and vice-versa. Volume is the amount of space an object occupies. Using the imperial system of measurement, volume is expressed in cubic inches, cubic feet, etc.; using the metric system, volume is expressed in cubic centimeters (cm^3), liters (L), or milliliters (mL). Once can measure the density of an object by dividing its mass over the volume. To get the sense of density, think about a 30cm by 30cm piece of metal and a piece of cotton cloth. Even though both have the same volume, they will have different masses; therefore, the density will be different. Density tells us if the material is going to sink or float in different solutions. Water has a density of 1.00g/cm3. Any substance with less density than water is going to float in water; any substance with more density than water will sink in water. Conductivity refers to how well an object can conduct electricity or thermal energy (i.e., heat). Electrical conductivity is a measure of a substance's ability to conduct an electric current. Thermal conductivity refers to the intensive property of a substance, which indicates its ability to conduct heat. https://uciunex.instructure.com/courses/9475/pages/refresher-physical-properties-of-matter?module_item_id=480768

SMR 2.6.b: Predict charges or poles on the basis of attraction/repulsion observations.

Objects that are strongly magnetic are called ferromagnetic. They may either be hard, which means the object does not lose its magnetism easily after being initially magnetized, or soft, meaning the objects loses its magnetism after being magnetized. When an object is magnetized, all the dipoles, molecular magnets, become aligned. A magnet's pole is a point in a magnet at which its magnetic force is concentrated. The two poles, north and south, point to the magnet's magnetic pole, a south or north magnetic pole. The first law of magnetism states that like poles repel and unlike poles attract. http://sciencecsetprep.weebly.com/electricity-and-magnetism.html

SMR 3.1.d: Analyze the similarities and differences among prokaryotic and eukaryotic cells and viruses.

Prokaryotes are single-celled organisms. Their cells do not have an organized nucleus. They are the simplest and smallest type of organism that can live independently. They are the evolutionary precursors to eukaryotic cells. They are essential as they help recycle Earth's nutrients, decompose waste, and even help make the sun's energy available to all animal life! General characteristics of prokaryotes: - Cell wall: A tough wall made out of peptidoglycan is present in most prokaryotes. They get their tensile strength from murein. Muramic acid, one of the major molecules of murein, never occurs in the cell walls of the eukaryotic cells. Penicillin is effective because it inhibits the synthesis of murein and, as a result, the production of bacteria. Penicillin does not work against eukaryotic cells. Cell membrane: This is similar to that in eukaryotic cells, except that the prokaryotic cell membrane lacks cholesterol and other steroids. In archaeobacteria, the cell membrane is composed of modified branched fatty acids. In Eubacteria, the membrane is composed of straight-chain fatty acids. The surface area of some prokaryotes is increased by convolutions (folds and loops). This convoluted cell membrane has incorporated the electron transport systems and enzymes necessary for the chemical events during respiration. - Cytoplasm: Highly granulated due to the large presence of ribosomes (the only cellular organelles found in most prokaryotes). Ribosomes function the same as they do in the eukaryotic cells by being the sites of protein synthesis. - DNA: Unlike eukaryotes which store their DNA in the nucleus of cells, prokaryotic cells have no membrane-bound organelles. Instead, prokaryotic cells contain a circular molecule of DNA that is not enclosed by a membrane. - Reproduction: DNA is replicated first. Then, the cell wall and the plasma membrane grow inward, ultimately dividing the cell into two. This cell division is called binary fission. They can also reproduce asexually by conjugation, transduction, and transformation. - Locomotion: A few prokaryotes have a flagellum that allows them to swim and move. These tails are connected to the cell using several interlocking proteins. The flagella of prokaryotes and eukaryotes have different proteins and internal structures. Both have the same function. The ability to swim is called cell motility, and this ability represents a big step in evolution. A motile organism can hunt for food, seek mates, avoid danger, and more. A group of prokaryotes known as the archaea can be found in very harsh environments, such as salt lakes, in the digestive tract of animals and insects, hot sulfur springs, and hydrothermal vents. Archaea look like bacteria, but there are some distinct differences and similarities between the two. They both measure around 1-3 micrometers in diameter if they are round and 2-4 micrometers in length for rod-shaped individuals. While they both can be round or rod-shaped, bacteria can come in a few other shapes such as corkscrew (spirilla), flexible spirals (spirochetes), curves (vibrios), and others are shapeless and do not possess a constant shape; both can live in aerobic and anaerobic environments; their cell walls are supported differently in that the polymer peptidoglycan that supports the bacteria and the Archaea is pseudomurein; the bacteria's membranes consist of fatty acids of straight-chain and the archeae's membrane consists of massive branched-chain fatty acids; unlike bacteria, archaea can produce methane gas from carbon dioxide; unlike archaea, bacteria can convert the sun's energy to chemical energy through photosynthesis; unlike archaea, some bacteria can cause diseases in plants and animals. These simple organisms can do so much! A short list of the tasks they can carry out includes: recycle carbon, nitrogen, sulfur, phosphorus, and metals; perform photosynthesis; decompose dead organic matter; produce greenhouse gases; cause diseases in plants, animals, and insects; protect the body from infection and even strengthen the immune system; digest fibers in animal diets. Eukaryotes are everything else aside from bacteria and archaea. Eukaryotes are more complex than prokaryotes. Both plants and animals consist of eukaryotic cells. The first eukaryotes appeared about 3.5 billion years ago. Over the next 2.5 billion years, the cells became more sturdy. The first eukaryotes likely evolved from prokaryotes that caught and digested other prokaryotes. The idea is that most of the time, a predator cell would digest the smaller cell. Sometimes, however, a few pieces of the ingested cell remained intact inside of the predator. A few of these pieces would serve a purpose. Over time, the predator cells that had ingested other prokaryotes would become more complicated due to those pieces, and eventually, a new type of cell developed. This new cell contained internal structures that carried out specific functions. Thus, the organelles of eukaryotic cells evolved. General characteristics of eukaryotes: - Cell wall: There are two types, the Gram-positive cell wall and the Gram-negative cell wall. In 1884, a Danish microbiologist named Hans Christian Gram developed a technique for staining bacteria. This technique became useful in distinguishing groups of organisms, particularly among the Eubacteria. The idea behind Gram staining is based on the cell's ability to absorb certain dyes. Bacterial cell walls made up of peptidoglycans (amino sugars) absorb the purple dye, and washing those cells with alcohol does not remove the dye. These purple-staining cells are called Gram-positive. On the other hand, cell walls composed of lipopolysaccharide that do not hold on to the purple dye and can easily be bleached with alcohol are called Gram-negative. These cells stain red with dyes such as safranin. Gram-positive have a thick layer of peptidoglycan, which absorbs the Gram stain. Gram-negative have a thick lipid bilayer on the outside, which is selectively permeable--not everything can pass through it; one of those is the Gram stain. The composition of the cell wall Gram-positive versus Gram-negative can tell us about the behavior of the cell. Gram-positive bacteria are more susceptible to antibiotics than gram-negative bacteria since things can pass through their cell walls more easily. - Nucleus: Contains one or more non-membrane bound areas called nucleoli where the cell manufactures ribosomes. -Ribosomes: These are small units found scattered in the cytoplasm that act as a protein synthesis site. - Mitochondrion: This is the site of respiration and energy generation. - Golgi apparatus: This makes various cellular products, sorts them, and packages them. - Endoplasmic reticulum: Site of membrane synthesis. Rough ER holds ribosomes; smooth ER lacks ribosomes. - Lysosome: Digests food and only exists in animal cells. - Centrosome: Produces slender tubules that guide the process of cell division. - Peroxisome: Produces hydrogen peroxide from excess oxygen molecules and degrades the hydrogen peroxide to protect the cell from damage. - Chloroplast: Site of photosynthesis, only found in plant cells. - Vacuole: Sac that stores excess food, digests some foods, and breaks down waste. Except for the ribosomes, the rest of the organelles in the list make eukaryotes different from prokaryotes. Protists are single-celled eukaryotes. They are very diverse in cell shape, flexibility, methods of swimming, methods for finding and ingesting food, and reproduction. They are similar to prokaryotes because they make their way through life on their own. They find their own food, sense and react to danger, and reproduce without any other cells. Like eukaryotes, they have more complex structures and often more complex life cycles. Examples of protists include amoeba, diplomonads, algae, oomycetes, and ciliates. Viruses are small parasitic things that exist in the gray area between living and nonliving. They resemble living things as they have small nucleic acid units, either RNA or DNA, that are surrounded by a protective protein coat (capsid). They are also able to replicate--an ability that living things can perform, not the non-living. However, they do not take in nutrients, grow, reproduce independently, maintain homeostasis, or sense and respond to their environment around them. Their "life cycle" is interesting. Viruses are known as phages and can only survive by infecting a live cell and turning it into a factory to manufacture more viruses. They reproduce by hijacking a cell's functions. Viruses slip their DNA or RNA across the plasma membrane and enter the nucleus. The cell's DNA is infiltrated. There are two known methods for how viruses reproduce and spread after this infiltration occurs: - Lytic cycle: In this cycle, the phage ends up destroying the host cell. As these copied nucleic acids organize as phages and the number of phages becomes too large for the host cell to hold, the cell membrane breaks and releases the phage to infect neighboring cells. The cycle then continues. - Lysogenic cycle: In this method, the virus does not kill the host cell. When the virus inserts its DNA or RNA into the host cell, it is incorporated into its chromosomes. The viral DNA/RNA is replicated along with chromosomal material. Lysogeny can continue for many cycles. The cell continues to manufacture and ship new batches of the virus with an intent to spread infection. At some point in lysogeny, under certain conditions, the virus switches over to the lytic cycle. http://sciencecsetprep.weebly.com/cell-biology-and-physiology.html

SMR 2.6.d: Demonstrate knowledge of how energy is stored and can change in electric and magnetic fields.

The analogy between electric current in a circuit and water in a water park is a useful one. In the instance of two water slides next to each other, water flows from the top of the double slide down to the bottom. One slide is wide and straight, the other narrow and winding. The two slides spill into two canals, with both canals spilling into a common pool. A pump carries the water back up to the top of the slides. A valve can shut off the supply of water. The water is analogous to electric current. The current flows through the entire circuit at once, rather than starting at one terminal at one time and passing through various circuit elements at other times. The canal is analogous to conducting wire that carries the electricity through the circuit. The valve is analogous to a switch that turns the electricity on and off. The slides are like light bulbs or other loads in an electric circuit, where energy is dissipated. The pump is analogous to a voltage source. The battery or other source provides the voltage, just as the water pump gets the water back up to the top of the slide. Energy is required to get water uphill to the top of the slide, just as energy is required to move electrons inside the battery from one terminal to the other. The difference in water level is like the potential difference between two points in a circuit. Water will not flow unless there is a difference in pressure (caused by a difference in level above ground, or a pump to raise its level). Similarly, the electrons will not flow through a circuit unless there is a potential difference (also called voltage difference) between two points in the circuit and a voltage source to sustain that potential difference. Mechanical resistance from the pipes or slides in the water park is like electrical resistance in the electric circuit. Sections of the water park in which the canal or slide become narrow and winding, resisting the flow of water, are like resistors in an electrical circuit. (Note that electrical resistance increases with the length of wire, which is not so evidence from the water park analogy. Sources of voltage (and hence current and power) in electrical circuits include batteries, electric generators, fuel cells, and solar cells, among others. Sources may also be called electromotive force (emf) devices. A battery--such as might be used in a flashlight (which should properly be called a cell, or a galvanic cell, or a voltaic cell, as "battery" refers to two or more cells connected together)--converts chemical energy into electricity. Inside the cell are two electric plates called electrodes. The anode or negative electrode is in contact with a chemical that readily gives up electrons--an electron "donor." The cathode, or positive electrode, is similarly in contact with a chemical that is receptive to electrons. On the outside of a cell or battery, the electrodes are called terminals and marked as positive or negative. When the cell or battery is connected to an electrical circuit--that is, when there is a closed path for the electrons to travel in--the two chemicals inside the cell undergo a chemical reaction that produces electrons. If a cell is not connected to a circuit, the chemical reaction does not occur. That's why you can keep a battery on a shelf until it is needed. (Some deterioration of the cell does occur over time.) When the chemical reactions in a cell have completed, there is no more chemical potential energy. The cell can no longer supply voltage to a circuit and is said to be "dead." A rechargeable battery is made from materials in which the chemical reaction can be reversed. When the battery or cell has been "recharged" or re-energized, it is ready to undergo the electron-producing reactions again. Other types of cells use other sources of energy to generate a voltage between two terminals: - A solar cell converts the energy in photons of sunlight into electrical energy. - A fuel cell is like a battery or galvanic cell, except that the fuel is continuously supplied. - An electric generator converts mechanical energy into electrical energy. The mechanical energy could come from a hard crank, a water turbine, a wind turbine, or some other source. Energy is stored in a cell or battery. Energy does not actually flow through wires in a circuit, along with the current--it is stored in electric fields surrounding the circuit. However, the flow of current powers appliances and dissipates energy. Electrical energy can be converted to heat, light, motion, or sound. A light bulb filament is made of highly resistive wire. Electrons passing through a filament slow down and some of their energy goes into heating the filament. As the filament is heated, it glows. A toaster also has highly resistive wires inside. They heat up to the point of flowing orange or red. The heat is intense enough to toast bread. In a fan, electrical energy is converted to motion of the blades. This conversion involves an electromotor. A hair-dryer produces sound as well as heat. https://uciunex.instructure.com/courses/9455/pages/energy-in-electrical-circuits?module_item_id=479331

SMR 3.4.d: Demonstrate knowledge of how the coding of DNA controls the expression of traits by genes and influences essential life functions (e.g., how DNA determines protein structure and other heritable genetic variations).

DNA is the genetic material of all organisms on Earth. When DNA is transmitted from parents to children, it can determine some of the children's characteristics (such as their eye color or hair color). But how does the sequence of a DNA molecule actually affect a human or other organism's features? For example, how did the sequence of nucleotides (As, Ts, Cs, and Gs) in the DNA of Mendel's pea plants determine the color of their flowers? A DNA molecule isn't just a long, boring string of nucleotides. Instead, it's divided up into functional units called genes. Each gene provides instructions for a functional product, that is, a molecule needed to perform a job in the cell. In many cases, the functional product of a gene is a protein. For example, Mendel's flower color gene provides instructions for a protein that helps make colored molecules (pigments) in flower petals. The functional products of most known genes are proteins, or, more accurately, polypeptides. Polypeptide is just another word for a chain of amino acids. Although many proteins consist of a single polypeptide, some are made up of multiple polypeptides. Genes that specify polypeptides are called protein-coding genes. Not all genes specify polypeptides. Instead, some provide instructions to build functional RNA molecules, such as the transfer RNAs and ribosomal RNAs that play roles in translation. Many genes provide instructions for building polypeptides. How, exactly, does DNA direct the construction of a polypeptide? This process involves two major steps: transcription and translation. - In TRANSCRIPTION, the DNA sequence of a gene is copied to make an RNA molecule. This step is called transcription because it involves rewriting, or transcribing, the DNA sequence in a similar RNA "alphabet." In eukaryotes, the RNA molecule must undergo processing to become a mature messenger RNA (mRNA). - In TRANSLATION, the sequence of the mRNA is decoded to specify the amino acid sequence of a polypeptide. The name translation reflects that the nucleotide sequence of the mRNA sequence must be translated into the completely different "language" of amino acids. Thus, during expression of a protein-coding gene, information flows from DNA --> RNA --> protein. This directional flow of information is known as the central dogma of molecular biology. Non-protein-coding genes (genes that specify functional RNAs) are still transcribed to produce an RNA, but this RNA is not translated into a polypeptide. For either type of gene, the process of going from DNA to a functional product is known as gene expression. In transcription, one strand of the DNA that makes up a gene, called the non-coding strand, acts as a template for the synthesis of a matching (complementary) RNA strand by an enzyme called RNA polymerase. This RNA strand is the primary transcript. The primary transcript carries the same sequence information as the non-transcribed strand of DNA, sometimes called the coding strand. However, the primary transcript and the coding strand of DNA are not identical, thanks to some biochemical differences between DNA and RNA. One important difference is that RNA molecules do not include the base thymine (T). Instead, they have the similar base uracil (U). Like thymine, uracil pairs with adenine. In bacteria, the primary RNA transcript can directly serve as a messenger RNA, or mRNA. Messenger RNAs get their name because they act as messengers between DNA and ribosomes. Ribosomes are RNA-and-protein structures in the cytosol where proteins are actually made. In eukaryotes (such as humans), a primary transcript has to go through some extra processing steps in order to become a mature mRNA. During processing, caps are added to the ends of the RNA, and some pieces of it may be carefully removed in a process called splicing. These steps do not happen in bacteria. The location of transcription is also different between prokaryotes and eukaryotes. Eukaryotic transcription takes place in the nucleus, where the DNA is stored, while protein synthesis takes place in the cytosol. Because of this, a eukaryotic mRNA must be exported from the nucleus before it can be translated into a polypeptide. Prokaryotic cells, on the other hand, don't have a nucleus, so they carry out both transcription and translation in the cytosol. After transcription (and, in eukaryotes, after processing), an mRNA molecule is ready to direct protein synthesis. The process of using information in an mRNA to build a polypeptide is called translation. During translation, the nucleotide sequence of an mRNA is translated into the amino acid sequence of a polypeptide. Specifically, the nucleotides of the mRNA are read in triplets (groups of three) called codons. There are 61 codons that specify amino acids. One codon is a "start" codon that indicates where to start translation. The start codon specifies the amino acid methionine, so most polypeptides begin with this amino acid. Three other "stop" codons signal the end of a polypeptide. These relationships between codons and amino acids are called the genetic code. Translation takes place inside of structures known as ribosomes. Ribosomes are molecular machines whose job is to build polypeptides. Once a ribosome latches on to an mRNA and finds the "start" codon, it will travel rapidly down the mRNA, one codon at a time. As it goes, it will gradually build a chain of amino acids that exactly mirrors the sequence of codons in the mRNA. How does the ribosome "know" which amino acid to add for each codon? As it turns out, this matching is not done by the ribosome itself. Instead, it depends on a group of specialized RNA molecules called transfer RNAS (tRNAs). Each tRNA has a three nucleotides sticking out at one end, which can recognize (base-pair with) just one or a few particular codons. At the other end, the tRNA carries an amino acid - specifically, the amino acid that matches those codons. There are many tRNAs floating around in a cell, but only a tRNA that matches (base-pairs with) the codon that's currently being read can bind and deliver its amino acid cargo. Once a tRNA is snugly bound to its matching codon in the ribosome, its amino acid will be added to the end of the polypeptide chain. This process repeats many times, with the ribosome moving down the mRNA one codon at a time. A chain of amino acids is built up one by one, with an amino acid sequence that matches the sequence of codons found in the mRNA. Translation ends when the ribosome reaches a stop codon and releases the polypeptide. Once the polypeptide is finished, it may be processed or modified, combine with other polypeptides, or be shipped to a specific destination inside or outside the cell. Ultimately, it will perform a specific job needed by the cell or organism - perhaps as a signaling molecule, structural element, or enzyme! - DNA is divided up into functional units called genes, which may specify polypeptides (proteins and protein subunits) or functional RNAs (such as tRNAs and rRNAs). - Information from a gene is used to build a functional product in a process called gene expression. - A gene that encodes a polypeptide is expressed in two steps. In this process, information flows from DNA --> RNA --> protein, a directional relationship known as the central dogma of molecular biology. - Transcription: One strand of the gene's DNA is copied into RNA. In eukaryotes, the RNA transcript must undergo additional processing steps in order to become a mature messenger RNA (mRNA). - Translation: The nucleotide sequence of the mRNA is decoded to specify the amino acid sequence of a polypeptide. This process occurs inside a ribosome and requires adapter molecules called tRNAs. - During translation, the nucleotides of the mRNA are read in groups of three called codons. Each codon specifies a particular amino acid or a stop signal. This set of relationships is known as the genetic code.

SMR 2.4.b: Demonstrate knowledge of the relationship between wave frequency, wavelength, and amplitude and energy.

Electromagnetic radiation is one of the many ways that energy travels through space. The heat from a burning fire, the light from the sun, the X-rays used by your doctor, as well as the energy used to cook food in a microwave are all forms of electromagnetic radiation. While these forms of energy might seem quite different from one another, they are related in that they all exhibit wavelike properties. While it's good to have a basic understanding of what electromagnetic radiation is, most chemists are less interested in the physics behind this type of energy and are far more interested in how these waves interact with matter. As you might already know, a wave has a trough (lowest point) and a crest (highest point). The vertical distance between the tip of a crest and the wave's central axis is known as its amplitude. The horizontal distance between two consecutive troughs or crests is known as the wavelength of a wave. The quantity known as the wave's frequency refers to the number of full wavelengths that pass by a given point in space every second; the SI unit for frequency is Hertz (Hz), which is equivalent to "per seconds" (written as 1 / s or s^-2). As you might imagine, wavelength and frequency are inversely proportional: that is, the shorter the wavelength, the higher the frequency, and vice versa. This relationship is given by the following equation: c = lv where l (the Greek lambda) is the wavelength (in meters, m) and v (the Greek nu) is the frequency (in Hertz, Hz). Their product is the constant c, the speed of light, which is equal to 3.00 x 10^8 m/s. This relationship reflects an important fact: all electromagnetic radiation, regardless of wavelength or frequency, travels at the speed of light. A wave's period is the length of time it takes for one wavelength to pass by a given point in space. Mathematically, the period (T) is simply the reciprocal of the wave's frequency (f): T = 1 / f Electromagnetic waves can be classified and arranged according to their various wavelengths/frequencies; this classification is known as the electromagnetic spectrum. To the right of the visible spectrum, we find the types of energy that are lower in frequency (and thus longer in wavelength) than visible light. These types of energy include infrared (IR) rays (heat waves given off by thermal bodies), microwaves, and radio waves. Lower frequency waves are lower in energy, and thus not dangerous to our health. Gamma rays, being the highest in frequency and energy, are the most damaging. Planck observed that matter actually absorbed or emitted energy only in whole-number multiples of the value hv, where h is Planck's constant, 6.626 x 10^-34 Js, and v is the frequency of the light absorbed or emitted. This was a shocking discovery because it challenged the idea that energy was continuous, and could be transferred in any amount. The reality, which Planck discovered, is that energy is not continuous but quantized--meaning that it can only be transferred in individual "packets" (or particles) of the size hv. Each of these energy packets is known as a quantum (plural: quanta). Just as we cannot pay the cashier at the store half a cent, energy cannot be transferred in anything less than a single quantum. We can think of quanta as being like "pennies" of electromagnetic energy--the smallest possible units by which such energy can be transferred. When a photon is absorbed, its energy is transferred to that atom or molecule. Because energy is quantized, the photon's entire energy is transferred (remember that we cannot transfer fractions of quanta, which are the smallest possible individual "energy packets"). When an atom or molecule loses energy, it emits a photon that carries energy exactly equal to the loss in energy of the atom or molecule. This change in energy is directly proportional to the frequency of the photon emitted or absorbed. This relationship is given by Planck's famous equation: E = hv where E is the energy of the photon absorbed or emitted (given in Joules, J), v is the frequency of the photon (given in Hertz, Hz), and h is Planck's constant, 6.626 x 10^-34 Js. Electromagnetic radiation can be described by its amplitude (brightness), wavelength, frequency, and period. By the equation E = hv, we have seen how the frequency of a light wave is proportional to its energy. At the beginning of the twentieth century, the discovery that energy is quantized led to the revelation that light is not only a wave but can also be described as a collection of particles known as photons. Photons carry discrete amounts of energy called quanta. This energy can be transferred to atoms and molecules when photons are absorbed. Atoms and molecules can also lose energy by emitting photons. https://www.khanacademy.org/science/ap-chemistry/electronic-structure-of-atoms-ap/bohr-model-hydrogen-ap/a/light-and-the-electromagnetic-spectrum

SMR 1.2.b: Evaluate design solutions in terms of their scientific and engineering constraints and the environmental, social, and cultural impacts of these solutions.

From NGSS SEPs: - Analyze complex real-world problems by specifying criteria and constraints for successful solutions. - Design a solution to a complex real-world problem, based on scientific knowledge, student-generated sources of evidence, prioritized criteria, and tradeoff considerations. - Evaluate a solution to a complex real-world problem, based on scientific knowledge, student-generated sources of evidence, prioritized criteria, and tradeoff considerations. From NGSS DCIs: - Criteria and constraints also include satisfying any requirements set by society, such as taking issues of risk mitigation into account, and they should be quantified to the extent possible and stated in such a way that one can tell if a given design meets them. - Humanity faces major global challenges today, such as the need for supplies of clean water and food or for energy sources that minimize pollution, which can be addressed through engineering. These global challenges also may have manifestations in local communities. - When evaluating solutions, it is important to take into account a range of constraints, including cost, safety, reliability, and aesthetics, and to consider social, cultural, and environmental impacts. - Criteria may need to be broken down into simpler ones that can be approached systematically, and decisions about the priority of certain criteria over others (trade-offs) may be needed. From NGSS CCs: - New technologies can have deep impacts on society and the environment, including some that were not anticipated. Analysis of costs and benefits is a critical aspect of decisions about technology. https://ngss.nsta.org/Practices.aspx?id=1

SMR 3.2.g: Demonstrate knowledge of the conversion, flow, and storage of energy in the cell.

- Through the process of cellular respiration, the energy in food is converted into energy that can be used by the body's cells. - During cellular respiration, glucose and oxygen are converted into carbon dioxide and water, and the energy is transferred to ATP. The main reason you need to eat is to get energy. Food is your body's only supply of energy. However, this energy must be converted from the apple (or any other food you eat) into an energy source your body can use. The process of getting energy from your food is called cellular respiration. How does the food you eat provide energy? When you need a quick boost of energy, you might reach for an apple or a candy bar. But cells do not "eat" apples or candy bars; these foods need to be broken down so that cells can use them. Through the process of cellular respiration, the energy in food is changed into energy that can be used by the body's cells. Initially, the sugars in the food you eat are digested into the simple sugar glucose, a monosaccharide. Recall that glucose is the sugar produced by the plant during photosynthesis. The glucose, or the polysaccharide made from many glucose molecules, such as starch, is then passed to the organism that eats the plant. This organism could be you, or it could be the organism that you eat. Either way, it is the glucose molecules that hold the energy. Specifically, during cellular respiration, the energy stored in glucose is transferred to ATP. ATP, or adenosine triphosphate, is chemical energy the cell can use. It is the molecule that provides energy for your cells to perform work, such as moving your muscles as you walk down the street. But cellular respiration is slightly more complicated than just converting the energy from glucose into ATP. Cellular respiration can be described as the reverse or opposite of photosynthesis. During cellular respiration, glucose, in the presence of oxygen, is converted into carbon dioxide and water. Recall that carbon dioxide and water are the starting products of photosynthesis. What are the products of photosynthesis? The process can be summarized as: glucose + oxygen --> carbon dioxide + water. During this process, the energy stored in glucose is transferred to ATP. Energy is stored in the bonds between the phosphate groups (PO4-) of the ATP molecule. when ATP is broken down into ADP (adenosine diphosphate) and inorganic phosphate, energy is released. When ADP and inorganic phosphate are joined to form ATP, energy is stored. During cellular respiration, about 36 to 38 ATP molecules are produced for every glucose molecule. Cellular respiration involves many biochemical reactions. However, the overall process can be summed up in a single chemical equation: C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy (stored in ATP)

SMR 4.1.a: Demonstrate knowledge of the evidence for the Big Bang model (e.g., light spectra, motion of distant galaxies, spectra of primordial radiation).

The Big Bang theory is an explanation of the early development of the Universe. According to this theory the Universe expanded from an extremely small, extremely hot, and extremely dense state. Since then it has expanded and become less dense and cooler. The Big Bang is the best model used by astronomers to explain the creation of matter, space and time 13.7 billion years ago. Two major scientific discoveries provide strong support for the Big Bang theory: - Hubble's discovery in the 1920s of a relationship between a galaxy's distance from Earth and its speed; and - the discovery in the 1960s of cosmic microwave background radiation. Early in the 20th century the Universe was thought to be static: always the same size, neither expanding nor contracting. But in 1924 astronomer Edwin Hubble used a technique pioneered by Henrietta Leavitt to measure distances to remote objects in the sky. Hubble used spectroscopic red-shift data to measure the speeds these objects were travelling then graphed their distance from Earth against their speed. He discovered that the speed at which astronomical objects move apart is proportional to their distance from each other. In other words, the farther away objects are from Earth, the faster they are moving away from us. This became known as Hubble's law. One explanation might be that the Earth is at the center of the Universe, and everything else is moving away from us, but that seems pretty unlikely! When scientists talk about the expanding Universe, they mean that it has been increasing in size ever since the Big Bang. But what exactly is getting bigger? Galaxies, stars, planets and the things on them like buildings, cars and people aren't getting bigger. Their size is controlled by the strength of the fundamental forces that hold atoms and sub-atomic particles together, and as far as we know that hasn't changed. Instead it's the space between galaxies that's increasing--they're getting further apart as space itself expands Hubble also realized that distant objects he'd been observing lay far beyond the Milky Way. This was the first time humans discovered that structures existed outside the Milky Way. We now know that the objects that Hubble observed are galaxies, similar to our own Milky Way, and that there are billions of them in the observable Universe. Hubble's discovery provided additional evidence for what was to become known as Big Bang theory, first proposed by Georges Lemaitre in 1927. It was a major step forward for astronomy. Hubble's law allowed astronomers to calculate how long ago galaxies started moving apart, which provides an estimate of when the Big Bang occurred and how old the Universe is. Hubble initially underestimated distances to these remote galaxies. He calculated that the Universe was about 2 billion years old. Geologists immediately condemned Hubble's finding because they had measurements showing the Earth to be somewhere between 3 and 5 billion years old. The Universe couldn't possibly be younger than the stars and planets in it! According to the Big Bang theory, the Universe was initially very hot and dense. As it expanded, it cooled (your refrigerator works on the same idea, expanding a liquid into a gas to cool the inside). Cosmologists were able to calculate the theoretical temperature of today's Universe and began to search for evidence of it. The cosmic microwave background radiation (CMBR) that Penzias and Wilson observed is leftover heat radiation from the Big Bang. Today, CMBR is very cold due to expansion and cooling of the Universe. It's only 2.725 Kelvin (-270.4 °C), which is only 2.725 °C above absolute zero. Cosmic microwave background radiation fills the entire Universe and can be detected day and night in every part of the sky. Areas of different density led to the formation of galaxies and stars. After nine years of observation the WMAP survey produced a detailed temperature map of the entire sky. Colors indicate tiny variations in the temperature of background radiation. These correspond to places where galaxies formed. The WMAP survey provides strong evidence that supports the Big Bang theory. The pattern of radiation is similar to what astrophysicists predict it would be if the Universe started from a very dense state and expanded to its present size. The Big Bang was followed by a period of very rapid expansion and cooling known as 'inflation'. In March 2014 scientists from the Harvard-Smithsonian Centre for Astrophysics studying characteristics of cosmic microwave background radiation detected evidence to support inflation theory. Their observations, made at Amundsen-Scott South Pole Station, are believed to reflect the imprint of gravitational waves on the Universe in the first few moments after the Big Bang. About 380,000 years after the Big Bang the Universe became transparent to light. For the next several billion years, gravity slowed the expansion of the Universe. About 8 billion years after the Big Bang expansion of the Universe began to accelerate. Cosmologists believe that an effect called 'dark energy' is causing the Universe to expand by making matter repel other matter. At present, we still don't know what dark energy is.

SMR 3.1.e: Demonstrate knowledge of organelles and their structures and functions in the cell and how differences in the structure of cells are related to cell function.

- Organelles: Tiny bodies in the cytoplasm. - Nucleus: Enclosed in a double-membrane and communicates with the surrounding cytosol. Here, DNA is responsible for providing cells with unique characteristics. Found in both plant and animal cells. - Cell membrane: Regulate turgor pressure in plants by collecting water and pressing outward against the cell wall, providing rigidity in the plant cell. Found in both plant and animal cells. - Lysosomes (AKA waste disposal): A special type of round vacuole that contains powerful enzymes. Lysosomes take in bacteria and foreign bodies to be destroyed by enzymes. Outer skin does not allow enzymes out into the cell, but if the cell is damaged, then the skin disappears and the cell digests itself. Contains hydrolytic enzymes necessary for intracellular digestion. This organelle helps keep excessive macromolecules from building up in the cell. This is common in animal cells. Vacuoles behave this way in animal cells. They have double membranes, hydrolytic enzymes that are capable of destroying the cell, and are a special type of round vacuole. - Ribosomes: Tiny, round particles usually attached to the endoplasmic reticulum that are involved in the building of proteins from amino acids. "Coded" information is sent to the ribosomes in strands called the messenger RNA that pass on the codes so that ribosomes join the amino acids in the right way to make proteins. Ribosomes are also present as ribosomal RNA and molecules of transfer RNA "carry" the amino acids to the ribosomes. Some are attached to the membrane of the ER. These are involved in the synthesis of proteins. Ribosomes are also free in the cytoplasm. These synthesize proteins to be used in the cell during cellular respiration. They are found in both plant and animal cells. - Endoplasmic reticulum (ER) (AKA transport system): Flat sacs folding inward from the cell membrane and joining up with the nuclear membrane. It provides a large surface area for a reaction or fluid storage and a passageway for fluids passing through. ER with ribosomes is called the rough ER. ER without ribosomes is called the smooth ER. Spreads throughout the cytoplasm and extends from the cell membrane to the nucleus' membrane through a network of membranes that form channels, tubes, and flat sacs. The function is to move materials out of the cytoplasm and into the plasma membrane. It is found in both plant and animal cells. - Golgi apparatus (AKA delivery system): A special area of the smooth ER. It collects substances made in the cell. Once the sac fills up, it gets pinched off as a vacuole and it travels out of the cells via the cytoplasm. Consists of a series of membranes that are loosely applied to one another. The Golgi apparatus collects vesicles, wraps them in its membranes, and then transports them to the cell membrane where they exit the cell. It is found in both plant and animal cells. - Centrioles: Vital to cell division. In animals, they lie just outside the nucleus in the cytoplasm. They form an x-shape and are made of nine sets of three tiny tubes. They are only found in animal cells. - Nucleoli: One or two small round objects in the nucleus that produce the component parts of ribosomes which are carried out of the nucleus and assembled in the cytoplasm. They are then attached to the rough ER. They are found in both plant and animal cells. - Mitochondria: Commonly referred to as the "powerhouse," though can be described as the site of ATA synthesis. The mitochondria provide the cell the energy it needs to produce secretory products. The inner layer of the folds provides a large surface area for the vital chemical reactions which go on inside of the organelle. This is where simple substances that are taken into the cell are broken down to provide energy. They are surrounded by a double membrane, and this membrane has many folds which are covered with enzymes used for the chemical reactions that release energy. The degree of folding of the inner membrane is related to the energy requirements of the cell. They are found in both plant and animal cells. - Plastids: These are tiny bodies in the plant cell's cytoplasm. Leucoplasts store starch, oil, or protein. Chloroplasts contain chlorophyll to make food through photosynthesis. They are found in plant cells only. - Cytosol: The "soup" where organelles reside and metabolism occur. Made up mostly of water and full of proteins that control metabolism. Signals transduction, glycolysis, intercellular receptors, and transcription factors. - Peroxisomes: These are membrane-bound sacs filled with oxidative enzymes. In plant cells, they play a variety of roles such as converting fatty acids into sugar and assisting chloroplasts with photosynthesis. Within animal cells, peroxisomes protect the cells from the production of hydrogen peroxide. Hydrogen peroxide is produced to kill bacteria. Peroxisome enzymes then break down hydrogen peroxide into water and oxygen. These are membrane-bound sacs filled with oxidative enzymes. They resemble lysosomes, however, peroxisomes contain oxidizing enzymes. They are found in both plant and animal cells. - Glyoxysomes: Membrane-bound organelles found in the cytoplasm that resemble peroxisomes, however, these contain enzymes that allow them to convert fatty acids to carbohydrates. They are usually found in plant seedlings, the carbohydrates are used to build cell walls.

SMR 2.5.f: Analyze how chemical energy in fuel is transformed to heat.

Chemical energy is a type of stored potential energy contained in the specific structural arrangement of atoms or molecules. This arrangement is primarily the result of chemical bonds within a molecule. The chemical energy of a chemical substance can be transformed into other forms of energy by specific chemical reactions. For example, when a fuel is burned, the chemical energy is converted to heat energy. The majority of this type of energy is lost to the external environment. Green plants transform solar energy into chemical energy through the process known as photosynthesis. Other forms of energy such as electrical energy can be converted to chemical energy through electrochemical reactions. When digested food is metabolized within a biological organism, chemical energy is also converted into heat energy. Humans consume plants and/or humans eat animals that earlier had consumed plants. The stored chemical energy within the plant or animal cells is transferred into the cells of the human being's body. Most, if not all, of the human system processes such as digestion of food, the circulatory system, respiration, the immune system, etc., rely upon cells that are able to convert the stored chemical energy into work and heat in a process known as cellular respiration. Chemical energy is stored in foods we consume along with fuels we use and can be released when these types of molecules undergo chemical reactions. A chemical reaction refers to a series of chemical changes that result in the production of one or more new chemical substances. These types of chemical changes are always accompanied by a change in the overall energy of the system. This refers to the idea that energy is either given off or released during a specific reaction, or energy is taken in or consumed during a specific reaction. Endothermic reactions refer to specific reactions that utilize or take in energy in order for the reaction to take place. These types of reactions contain products that have more potential chemical energy than the reactants. When an athlete sustains a muscle injury during a basketball game, the team doctor will place a cold pack on the general location of the injury. In order to 'activate' the cold pack, a seal is broken that separates two containers from the plastic bag. As the contents from the separate containers begin to react, energy is absorbed from the surrounding environment. As the doctor places the cold pack on the injured location of the athlete, the athlete's body will begin to supply some of the energy that is required to get the reaction going. What the athlete experiences as "cold" has to do with the temperature of that area of the athlete's body changing as heat flows from the body to the cold-pack. Exothermic reactions refer to specific reactions that release or liberate energy. These types of reactions contain products, which have an overall decreased level of potential energy than the reactants since energy was primarily released in the form of heat. The water and the carbon dioxide in the example below carry less potential energy than the propane and oxygen. When you are standing next to a barbecue grill, you feel the heat being released by the combustion reaction that is taking place around the burners. https://uciunex.instructure.com/courses/9475/pages/refresher-how-chemical-energy-in-fuel-is-transformed-into-heat?module_item_id=480731

SMR 2.1.c: Apply knowledge of the development and organization of the periodic table and predict the properties of elements on the basis of their positions in the periodic table.

H. G. J. Moseley bombarded atomic nuclei with high energy radiation. He discovered through his experiments that nuclear charge increases by 1 for each element. Thus, the periodic law states that the properties of elements recur in a repeating pattern when arranged according to increasing atomic number. The arrangement of the elements starts on the left of the periodic table with hydrogen and moves in order of increasing atomic number. Each successive element has one more electron in the outer shell. A group is a vertical column in the periodic table. There are 18 columns and they are all named except for transition metals. Each column has the same number of electrons in their outer shell. Elements in the same group have similar chemical properties. Groups of elements can be referred to by their family names. Group 1 (1A) - alkali metals - Includes lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr) - Valence electron configuration of ns1 --> 1 electron in their valence shell - Highly reactive - React with water to from hydroxide ions to create basic solutions (also called alkaline solutions) - Soft texture - Silvery in color - Low in density - Low boiling and melting points - Although hydrogen is listed in group 1 due to its electron configuration, it is not included in the alkali group as it rarely exhibits similar behavior Group 2 (IIA) - alkaline earth metals - Includes beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra) - Soft - Silver metals that are less metallic in character than group 1 - Ca, Sr, Ba, and Ra are almost as reactive as the elements in group 1 - Two electrons in their valence shells - Oxidation state is +2, easily lose electrons - Form compounds via ionic bonds - When this group reacts with hydrogen --> hydride - When this group reacts with oxygen --> oxide - When this group reacts with a halogen --> halide Group 17 (VIIA) - halogens - Fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At) - 7 valence electrons, only require 1 more electron to form a full octet --> this makes them more reactive than other non-metal groups - Non-polar covalent single bonds - Never seen uncombined in nature - Fluorine is the most reactive halogen, astatine is the least reactive - Melting and boiling points increase down the group due to van der Waals forces - Size of the molecules increases down the group which increases in strength of van der Waals forces - Atomic radius increases down the group - Ionization energy decreases down the group as a result of the outer valence electrons being further from the nucleus --> requires less energy to pull off these outermost electrons - Increase in shielding is observed as we move down the group - Decrease in electronegativity is observed as we move down the group Group 18 (VIIIA) - noble gases - Argon (Ar), helium (He), neon (Ne), krypton (Kr), xenon (Xe), radon (Rn) - Atomic mass and atomic radii increases down the group - Outer shells are full, thus they are extremely stable, tend to not form chemical bonds, small tendency to gain or lose electrons - Weak interatomic forces and thus low boiling and melting points - Gases are odorless, colorless, and nonflammable Periods are the horizontal rows, of which there are seven. The 1st period has two elements: hydrogen and helium. The second and third periods each have 8 elements (called short periods). The fourth and fifth periods have 18 elements each (called long periods). Representative transition group: chemical behavior is predictable, found in the A groups on the left and right side of the periodic table Transition elements: B groups in the middle of the table, chemical behaviors are not as predictable Inner-transition elements: found in the main portion of the periodic table and are placed below the table in order to avoid a wide periodic table Lanthantide series: Ce through Lu, these have similar properties and are found in abundance in nature --> AKA rare earth elements Actinide series: all are radioactive and none of the elements after uranium are naturally occurring As you move up a group of elements from bottom to top, the radii of the atom decrease because there are fewer energy levels of electrons surrounding the nucleus. Thus, the trend in atomic radius decreases up as a group. As we move left to right within a period, the radii of the atoms decrease. Because the number of protons increases as we move left to right, the nuclear charge of the elements increases the pulling of electrons closer to the nucleus thus reducing the size of the atom. The unusual shape of the table is the result of the ordering of sublevels. The order of energy sublevels follow the systematic arrangement of the elements by groups. Left area is called S block of elements. Right area are called p blocks. Transition area are called the d blocks. Inner transition are called the f blocks. Number of sublevels corresponds to the number of main energy level --> 1s<2s<2p<3s<3p<4s<3d<4p<5s<4d<5p<6s... When an atom undergoes a chemical reaction, only the outermost electrons are involved, called valence electrons. They form chemical bonds between atoms and affect the chemical behavior of the element. Predicting the number of electrons by looking at the group number in the periodic table only works for representative elements. Group number is identical to the total number of valence electrons. For example, in group 1A, they all have 1 valence electron. Group 5A has 5. Group 13 has 3 (look at the last digit).

SMR 3.5.b: Demonstrate knowledge of the theory of natural selection, including how genetic variation and its expression leads to differences in characteristics among individuals in a population, adaptation, speciation, and extinction.

English naturalist Charles Darwin developed the idea of natural selection after a five-year voyage to study plants, animals, and fossils in South America and on islands in the Pacific. In 1859, he brought the idea of natural selection to the attention of the world in his best-selling book, On the Origin of Species. Natural selection is the process through which populations of living organisms adapt and change. Individuals in a population are naturally variable, meaning that they are all different in some ways. This variation means that some individuals have traits better suited to the environment than others. Individuals with adaptive traits--traits that give them some advantage--are more likely to survive and reproduce. These individuals then pass the adaptive traits on to their offspring. Over time, these advantageous traits become more common in the population. Through this process of natural selection, favorable traits are transmitted through generations. Natural selection can lead to speciation, where one species gives rise to a new and distinctly different species. It is one of the processes that drives evolution and helps to explain the diversity of life on Earth. Darwin chose the name natural selection to contrast with "artificial selection," or selective breeding that is controlled by humans. He pointed to the pastime of pigeon breeding, a popular hobby in his day, as an example of artificial selection. By choosing which pigeons mated with others, hobbyists created distinct pigeon breeds, with fancy feathers or acrobatic flight, that were different from wild pigeons. Darwin and other scientists of his day argued that a process much like artificial selection happened in nature, without any human intervention. He argued that natural selection explained how a wide variety of life forms developed over time from a single common ancestor. Darwin did not know that genes existed, but he could see that many traits are heritable--passed from parents to offspring. Mutations are changes in the structure of the molecules that make up genes, called DNA. The mutation of genes is an important source of genetic variation within a population. Mutations can be random (for example, when replicating cells make an error while copying DNA), or happen as a result of exposure to something in the environment, like harmful chemicals or radiation. Mutations can be harmful, neutral, or sometimes helpful, resulting in a new, advantageous trait. When mutations occur in germ cells (eggs and sperm), they can be passed on to offspring. If the environment changes rapidly, some species may not be able to adapt fast enough through natural selection. Through studying the fossil record, we know that many of the organisms that once lived on Earth are now extinct. Dinosaurs are one example. An invasive species, a disease organism, a catastrophic environmental change, or a highly successful predator can all contribute to the extinction of species. Today, human actions such as overhunting and the destruction of habitats are the main cause of extinctions. Extinctions seem to be occurring at a much faster rate today than they did in the past, as shown in the fossil record. - Genetic variation is an important force in evolution as it allows natural selection to increase or decrease frequency of alleles already in the population. - Genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring). - Genetic variation is advantageous to a population because it enables some individuals to adapt to the environment while maintaining the survival of the population. - Genetic diversity: The level of biodiversity, refers to the total number of genetic characteristics in the genetic makeup of a species. - Crossing over: The exchange of genetic material between homologous chromosomes that results in recombinant chromosomes. - Phenotypic variation: Variation (due to underlying heritable genetic variation); a fundamental prerequisite for evolution by natural selection. - Genetic variation: Variation in alleles of genes that occurs both within and among populations.

SMR 1.1.b: Apply knowledge of the development of important scientific ideas and models over time and of how history shows that evaluating a model's merits and limitations leads to its improvement.

From NGSS: A practice of both science and engineering is to use and construct models as helpful tools for representing ideas and explanations. These tools include diagrams, drawings, physical replicas, mathematical representations, analogies, and computer simulations. - Evaluate limitations of a model for a proposed object or tool. - Develop or modify a model--based on evidence--to match what happens if a variable or component of a system is changed. - Use and/or develop a model of simple systems with uncertain and less predictable factors. - Develop and/or revise a model to show the relationships among variables, including those that are not observable but predict observable phenomena. - Develop and/or use a model to predict and/or describe phenomena. - Develop a model to describe unobservable mechanisms. - Develop and/or use a model to generate data to test ideas about phenomena in natural or designed systems, including those representing inputs and outputs, and those at unobservable scales. Modeling can begin in the earliest grades, with students' models progressing from concrete "pictures" and/or physical models (e.g., a toy car) to more abstract representations of relevant relationships in later grades, such as a diagram representing forces on a particular object in a system. Models include diagrams, physical replicas, mathematical representations, analogies, and computer simulations. Although models do not correspond exactly to the real world, they bring certain features into focus while obscuring others. All models contain approximations and assumptions that limit the range of validity and predictive power, so it is important for students to recognize their limitations. In science, models are used to represent a system (or parts of a system) under study, to aid in the development of questions and explanations, to generate data that can be used to make predictions, and to communicate ideas to others. Students can be expected to evaluate and refine models through an iterative cycle of comparing their predictions with the real world and then adjusting them to gain insights into the phenomenon being modeled. As such, models are based upon evidence. When new evidence is uncovered that the models can't explain, models are modified. In engineering, models may be used to analyze a system to see where or under what conditions flaws might develop, or to test possible solutions to a problem. Models can also be used to visualize and refine a design, to communicate a design's features to others, and as prototypes for testing design performance. https://ngss.nsta.org/Practices.aspx?id=2

SMR 1.3.g: Analyze the factors contributing to stability and change in systems (e.g., static and dynamic equilibrium, feedback) and the rates at which systems change.

From NGSS: For both designed and natural systems, conditions that affect stability and factors that control rates of change are critical elements to consider and understand. - Stability may be disturbed either by sudden events or gradual changes that accumulate over time. - Explanations of stability and change in natural and designed systems can be constructed by examining the changes over time and processes at different scales, including the atomic scale. - Small changes in one part of a system might cause large changes in another part. - Systems in dynamic equilibrium are stable due to a balance of feedback mechanisms. Such stability can take different forms, with the simplest being a static equilibrium, such as a ladder leaning on a wall. By contrast, a system with steady inflows and outflows (i.e., constant conditions) is said to be in dynamic equilibrium. A repeating pattern of cyclic change--such as the moon orbiting Earth--can also be seen as a stable situation, even though it is clearly not static. "An understanding of dynamic equilibrium is crucial to understanding the major issues in any complex system--for example, population dynamics in an ecosystem or the relationship between the level of atmospheric carbon dioxide and Earth's average temperature. Dynamic equilibrium is an equally important concept for understanding the physical forces in matter. Stable matter is a system of atoms in dynamic equilibrium." "In designing systems for stable operation, the mechanisms of external controls and internal 'feedback' loops are important design elements; feedback is important to understanding natural systems as well. A feedback loop is any mechanism in which a condition triggers some action that causes a change in the same condition, such as the temperature of a room triggering the thermostatic control that turns the room's heater on or off." https://ngss.nsta.org/CrosscuttingConcepts.aspx?id=7

SMR 3.1.c: Demonstrate knowledge of evidence that living things are made of cells.

The first characteristic of a living thing is that they are made up of cells. A cell is the basic building block of all organisms. It is the smallest unit of organization in a living thing. In a 1665 publication called Micrographia, experimental scientist Robert Hooke coined the term "cell" for the box-like structures he observed when viewing cork tissue through a lens. In the 1670s, van Leeuwenhoek discovered bacteria and protozoa. Later advances in lenses, microscope construction, and staining techniques enabled other scientists to see some components inside cells. By the late 1830s, botanist Matthias Schleiden and zoologist Theodor Schwann were studying tissues and proposed the unified cell theory. The unified cell theory states that: all living things are composed of one or more cells; the cell is the basic unit of life; and new cells arise from existing cells. Rudolf Virchow later made important contributions to this theory. Schleiden and Schwann proposed spontaneous generation as the method for cell origination, but spontaneous generation (also called abiogenesis) was later disproven. Rudolf Virchow famously stated "Omnis cellula e cellula"..."All cells only arise from pre-existing cells. "The parts of the theory that did not have to do with the origin of cells, however, held up to scientific scrutiny and are widely agreed upon by the scientific community today. The generally accepted portions of the modern Cell Theory are as follows: 1. The cell is the fundamental unit of structure and function in living things. 2. All organisms are made up of one or more cells. 3. Cells arise from other cells through cellular division. The expanded version of the cell theory can also include: - Cells carry genetic material passed to daughter cells during cellular division. - All cells are essentially the same in chemical composition. - Energy flow (metabolism and biochemistry) occurs within cells.

SMR 1.1.f: Use mathematics (e.g., dimensional analysis, statistics, proportional thinking) and computational thinking to represent and solve scientific problems and to assess scientific simulations.

From NGSS: In both science and engineering, mathematics and computation are fundamental tools for representing physical variables and their relationships. They are used for a range of tasks such as constructing simulations; statistically analyzing data; and recognizing, expressing, and applying quantitative relationships. - Use digital tools (e.g., computers) to analyze very large data sets for patterns and trends. - Use mathematical representations to describe and/or support scientific conclusions and design solutions. - Create algorithms (a series of ordered steps) to solve a problem). - Apply mathematical concepts and/or processes (such as ratio, rate, percent, basic operations, and simple algebra) to scientific and engineering questions and problems. - Use digital tools and/or mathematical concepts and arguments to test and compare proposed solutions to an engineering design problem. Although there are differences in how mathematics and computational thinking are applied in science and engineering, mathematics often brings these two fields together by enabling engineers to apply the mathematical form of scientific theories and by enabling scientists to use powerful information technologies designed by engineers. Students are expected to use mathematics to represent physical variables and their relationships, and to make quantitative predictions. Other applications of mathematics in science and engineering include logic, geometry, and at the highest levels, calculus. Computers and digital tools can enhance the power of mathematics by automating calculations, approximating solutions to problems that cannot be calculated precisely, and analyzing large data sets available to identify meaningful patterns. Students are also expected to engage in computational thinking, which involves strategies for organizing and searching data, creating sequences of steps called algorithms, and using and developing new simulations of natural and designed systems. Mathematics is a tool that is key to understanding science. As such, classroom instruction must include critical skills of mathematics. https://ngss.nsta.org/Practices.aspx?id=5

SMR 3.2.f: Analyze the processes of cellular respiration (anaerobic and aerobic).

Cellular respiration: The process by which organisms break down glucose into a form that the cell can use as energy. ATP: Adenosine triphosphate, the primary energy carrier in living things. Mitochondria: The eukaryotic cell structure where cellular respiration occurs. Cytoplasm: The contents of a cell between the plasma membrane and the nuclear envelope; includes cytosol which is the jelly-like substance that fills the space between organelles. Aerobic: Process that requires oxygen. Anaerobic: Process that does not require oxygen. Fermentation: An anaerobic pathway for breaking down glucose. Cellular respiration can occur both aerobically (using oxygen), or anaerobically (without oxygen). During aerobic cellular respiration, glucose reacts with oxygen, forming ATP that can be used by the cell. Carbon dioxide and water are created as byproducts. The overall equation for aerobic cellular respiration is: C6H12O6 + 6O2 --> 6CO2 + 6H2O + ATP The three stages of aerobic cellular respiration are glycolysis (an anaerobic process), the Krebs cycle, and oxidative phosphorylation. Some organisms are able to continually convert energy without the presence of oxygen. They undergo glycolysis, followed by the anaerobic process of fermentation to make ATP. - Muscle cells can continue to produce ATP when oxygen runs low using lactic acid fermentation. However, this often results in muscle fatigue and pain. - Many yeast use alcoholic fermentation to produce ethanol. For this reason, humans have domesticated yeast to use for many commercial purposes including baking as well as beer and wine production. Aerobic respiration: Reactants - Glucose and oxygen Products - ATP, water, CO2 Location - Cytoplasm (glycolysis) and mitochondria Stages - Glycolysis (anaerobic), Krebs cycle, oxidative phosphorylation ATP produced - Large amount (36 ATP) Anaerobic respiration: Reactants - Glucose Produces - ATP and lactic acid (animals); or ATP, ethanol, and CO2 (yeast) Location - Cytoplasm Stages - Glycolysis, fermentation ATP produced - Small amount (2 ATP) - Anaerobic respiration is a normal part of cellular respiration. Glycolysis, which is the first step in all types of cellular respiration is anaerobic and does not require oxygen. If oxygen is present, the pathway will continue on to the Krebs cycle and oxidative phosphorylation. However, if oxygen is not present, some organisms can undergo fermentation to continually produce ATP. - Plants undergo cellular respiration. Many people believe that plants undergo photosynthesis and animals undergo respiration. Really, plants do both! Plants simply undergo photosynthesis first as a way to make glucose. Animals don't need to photosynthesize since they get their glucose from the food they eat. - Cellular respiration is not simply the same as ''breathing." This can be confusing! People often use the word "respiration" to refer to the process of inhaling and exhaling. However, this is physiological respiration, not cellular respiration. The two are related processes, but they are not the same. Cellular respiration is one of the most elegant, majestic, and fascinating metabolic pathways on earth. At the same time, it's also one of the most complicated. When I learned about it for the first time, I felt like I had tripped and fallen into a can of organic-chemistry-flavored alphabet soup! Luckily, cellular respiration is not so scary once you get to know it. Let's start by looking at cellular respiration at a high level, walking through the four major stages, and tracing how they connect up to one another. During cellular respiration, a glucose molecule is gradually broken down into carbon dioxide and water. Along the way, some ATP is produced directly in the reactions that transform glucose. Much more ATP, however, is produced later in a process called oxidative phosphorylation. Oxidative phosphorylation is powered by the movement of electrons through the electron transport chain, a series of proteins embedded in the inner membrane of the mitochondrion. These electrons come originally from glucose and are shuttled to the electron transport chain by electron carriers NAD+ and FAD, which become NADH and FADH2 when they gain electrons. To be clear, this is what's happening in the diagram above when it says +NADH or +FADH2. The molecules isn't appearing from scratch, it's just being converted to its electron-carrying form: - NAD+ + 2e- + 2H+ --> NADH + H+ - FAD + 2e- + 2H+ --> FADH2 To see how a glucose molecule is converted into carbon dioxide and how its energy is harvested as ATP and NADH/FADH2 in one of your body's cells, let's walk step by step through the four stages of cellular respiration. 1. Glycolysis. In glycolysis, glucose--as six-carbon sugar--undergoes a series of chemical transformations. In the end, it gets converted into two molecules of pyruvate, a three-carbon organic molecule. In these reactions, ATP is made, and NAD+ is converted to NADH. 2. Pyruvate oxidation. Each pyruvate from glycolysis goes into the mitochondrial matrix--the innermost compartment of mitochondria. There, it's converted into a two-carbon molecule bound to Coenzyme A, known as acetyl CoA. Carbon dioxide is released and NADH is generated. 3. Citric acid cycle. The acetyl CoA made in the last step combines with a four-carbon molecule and goes through a cycle of reactions, ultimately regenerating the four-carbon starting molecule. ATP, NADH, and FADH2 are produced, and carbon dioxide is released. 4. Oxidative phosphorylation. The NADH and FADH2 made in other steps deposit their electrons in the electron transport chain, turning back into their "empty" forms (NAD+ and FAD). As electrons move down the chain, energy is released and used to pump protons out of the matric, forming a gradient. Protons flow back into the matrix through an enzyme called ATP synthase, making ATP. At the end of the electron transport chain, oxygen accepts electrons and takes up protons to form water. Glycolysis can take place without oxygen in a process called fermentation. The other three stages of cellular respiration--pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation--require oxygen in order to occur. Only oxidative phosphorylation uses oxygen directly, but the other two stages can't run without oxidative phosphorylation.

SMR 2.5.d: Demonstrate knowledge of how the transfer of energy as heat is related to changes in temperature and interpret the direction of heat flow in a system.

Heat is the form of energy transferred between two objects with varying temperatures. Temperature is a measure of quantity that scientists use to indicate the average energy of the movement of particles. Heat is added to matter when solids physically change state into liquids, and when liquids change state into gases (e.g., in melting, evaporation, and boiling). Heat is taken away from matter when gases physically change state into liquids and when liquids change state into solids (e.g., in condensation and freezing). What makes the liquid in a thermometer rise or fall in response to temperature? Which contains more heat—a boiling coffeepot or a swimming pool of lukewarm water? These types of questions can be answered when one considers the science behind heat transfer and its relationship to changes in temperature. Heat can be transferred from objects with a higher thermal energy (i.e., hotter objects) to surrounding objects with lower thermal energy. This transfer of heat can increase the overall kinetic energy (i.e., molecular motion) of the surrounding system, causing a differential in temperature. Heat transfer refers to the flow of heat from a hot object to one that is cold. The hotter object transfers heat, also known as thermal energy, to its cooler surroundings until thermal equilibrium is reached. https://uciunex.instructure.com/courses/9475/pages/refresher-heat-transfer-and-changes-in-temperature?module_item_id=480721

SMR 3.4.e: Demonstrate knowledge of the relationship between genes and their interaction with the environment in terms of organisms' development and functions.

The way that you carry a conversation, respond to failure, form relationships with others, and generally behave is in part related to your genetics--but your world and life experiences also shape your attitudes and behaviors. This combination of your genetics and experiences ultimately forms your identity and influences your behavior. Consider this example: Jennifer and Karen are identical twins. If both girls have genetic information (genes) associated with obesity, does this mean that they will have no control over their weight? Or, if the girls are adopted by different families and have different life experiences, will their environment dictate how much they will ultimately weigh? Genes are instructions that dictate how a person's body is made, in the same way that blueprints are instructions to build a house. Information from genes let the body know what characteristics a person will have, like if they will have hairy or hairless ears and/or a small or big chin. These instructions come from our parents; when their genes are mixed together, our set of genes is formed. This is why we often look like a mixture of our parents! I have my mother's blue eyes, but my father's stature. Almost everyone has different information in their genes, which makes sense given how much diversity there is in how people look and act. Now consider the exception--identical twins. Identical twins look exactly the same because each twin shares the same genes as their identical sibling. Why? When a mother is pregnant, the fertilized egg holds the mixture of genes from both the mother and father. Occasionally this fertilized egg splits into two eggs with the exact same mixture of genes. This results in two identical people who are similar to one another in the way they look and behave. Genes can carry instructions that can make it more likely for you to develop certain illnesses or conditions. For example, Jennifer and Karen both have genes associated with obesity. Their genes could tell their body to: - increase the size of their fat cells or dictate how they use fat in their body, - release chemicals (like hormones) which control hunger and appetite, - and/or influence behavior as Jennifer and Karen interact with their environment. For example, if Karen begins to gain weight, she may seek out fewer opportunities to exercise because going to the gym makes her feel uncomfortable. Suppose Jennifer is raised by wealthy parents who have access to the best, healthiest foods. Her parents cook nutritious meals like vegetable risotto and lentil soup and limit the amount of sugar, salt, and fat their daughter consumes. Jennifer learns to love fruits and vegetables, and doesn't crave excessively salty or sweet foods. Her parents have a significant amount of time to play with her and teach her to live an active lifestyle. By eating nutritious foods and staying physically active, the genes increasing her chance of developing obesity are not expressed and she never develops obesity. Karen however is raised by low-income parents who live in an area where fresh, healthy food is scarce and expensive. Because her parents can't afford fruits and vegetables, Karen eats a lot of frozen, packaged meals and fast food, which are higher in sugar, fat, and salt. Her parents both work multiple jobs, and Karen spends her time alone in front of the television. Karen's eating and physical activity habits enhance the expression of her genes for obesity. The characteristics (physical traits and behaviors) that you are born with and what you experience throughout your life are both important. Your characteristics can impact your experiences and your experiences can impact your characteristics. Karen and Jennifer's life experiences influenced when and how their genes were expressed. The relationship between your genes and behavior can change over time as you have new experiences. In some situations, genes play a larger role in determining your behavior; in other situations, environment plays a larger role in influencing your behavior. If you had a whole different set of experiences over your lifetime your genes may be expressed in different ways, and you may behave differently than you do now. If Jennifer and Karen had grown up in the same environment, their health behaviors would probably be more similar to one another. Scientists can look at the influence of genes on behavior by using a mathematical formula called a heritability estimate. Heritability estimates give information about how much of an impact genes have on a behavior in a certain environment. Think about blood type as an example--in your group of friends, there is probably some variation in your blood types. If differences in blood type are mostly influenced by genes then the heritability estimate would reflect that. Heritability estimates can range from 0 to 1; when the estimate is higher (closer to 1), this means that genes have a larger influence on the behavior of interest, as it would be with blood type. When the estimate is lower (closer to 0), it reflects a larger impact of the environment on the behavior. To study heritability, scientists use information from identical twins that were separated at birth, like Karen and Jennifer. They do this because the genetic material of identical twins is almost exactly the same, which makes it easier to determine the relative influence of the environment. To better understand heritability estimates, consider Karen and Jennifer again. In Karen's town where healthy food is scarce--many of her neighbors do not get enough to eat and are malnourished. The athletic ability of Karen and her neighbors is decreased and the heritability of athleticism is closer to 0, because their experiences in a financially poor environment have inhibited genes associated with athleticism. On the other hand, Jennifer and her neighbors eat plenty of healthy foods are well nourished. If we look at the athletic ability of Jennifer's neighbors, the heritability estimate is closer to 1 because their experiences in financially well off environment have enabled their athleticism genes to be expressed. A heritability estimate doesn't tell us about a person's chances for inheriting a certain genetic trait--Jennifer doesn't have a greater chance of being athletic because she lives in a well off neighborhood. Heritability estimates give us more information about groups of people, like Jennifer and her neighbors. The varying levels of athleticism among the people in her neighborhood can be explained by differences in their genetic makeup and differences in their life experiences. When we calculate a heritability estimate, it gages how much of the differences can be explained by each factor. - Why do you think heritability estimates cannot be generalized, or applied to different populations? Consider exactly what a heritability estimate measures--the relative influence of genes and the environment. If there was a change in the environment, the heritability estimate would change as well; an estimate from Jennifer's neighborhood would not be applicable in Karen's neighborhood. Each estimate is very specific to one group of individuals and their environment, which means that it could not be generalized. However, we can look at large groups of people and develop a range of estimates to tell us more about a particular trait of interest. The range allows for interpersonal and small group differences that are influenced by specific environments, but still gives us important information about the differences in people's traits. - The interactions between your genes and your environment are especially important during your early development. For example, exposure to toxins during and immediately after pregnancy can produce lasting effects on a baby's health--children exposed to pesticides at a young age have a higher risk of developing mental health problems later in life.

SMR 3.2.c: Recognize the hierarchical levels of organization (e.g., cells, tissues, organs, systems, organisms) in plants and animals.

Key points: - Humans--and other complex multicellular organisms--have systems of organs that work together, carrying out processes that keep us alive. - The body has levels of organization that build up on each other. Cells make up tissues, tissues make up organs, and organs make up organ systems. - The function of an organ system depends on the integrated activity of its organs. For instance, digestive system organs cooperate to process food. - The survival of the organism depends on the integrated activity of all the organ systems, often coordinated by the endocrine and nervous systems. If you were a single-celled organism and you lived in a nutrient-rich place, staying alive would be pretty straightforward. For instance, if you were an amoeba living in a pond, you could absorb nutrients straight from your environment. The oxygen you would need for metabolism could diffuse in across your cell membrane, and carbon dioxide and other wastes could diffuse out. When the time came to reproduce, you could just divide yourself in two! However, odds are you are not an amoeba--given that you're using Khan Academy right now--and things aren't quite so simple for big, many-celled organisms like human beings. Your complex body has over 30 trillion cells and most of those cells aren't in direct contact with the external environment. A cell deep inside your body--in one of your bones, say, or in your liver--can't get the nutrients or oxygen it needs directly from the environment. How, then, does the body nourish its cells and keep itself running? Let's take a closer look at how the organization of your amazing body makes this possible. Most cells in large multicellular organisms don't directly exchange substances like nutrients and wastes with the external environment, instead, they are surrounded by an internal environment of extracellular fluid--literally, fluid outside of cells. The cells get oxygen and nutrients from this extracellular fluid and release waste products into it. Humans and other complex organisms have specialized systems that maintain the internal environment, keeping it steady and able to provide for the needs of the cells. Different systems of the body carry out different functions. For example, your digestive system is responsible for taking in and processing food, while your respiratory system--working with your circulatory system--is responsible for taking up oxygen and getting rid of carbon dioxide. The muscular and skeletal systems are crucial for movement; the reproductive system handles reproduction; and the excretory system gets rid of metabolic waste. Because of their specialization, these different systems are dependent on each other. The cells that make up the digestive, muscular, skeletal, reproductive, and excretory systems all need oxygen from the respiratory system to function, and the cells of the respiratory system--as well as all the other systems--need nutrients and must get rid of metabolic wastes. All the systems of the body work together to keep an organism up and running. All living organisms are made up of one or more cells. Unicellular organisms, like amoebas, consist of only a single cell. Multicellular organisms, like people, are made up of many cells. Cells are considered the fundamental units of life. The cells in complex multicellular organisms like people are organized into tissues, groups of similar cells that work together on a specific task. Organs are structures made up of two or more tissues organized to carry out a particular function, and groups of organs with related functions make up the different organ systems. At each level of organization--cells, tissues, organs, and organ systems--structure is closely related to function. For instance, the cells in the small intestine that absorb nutrients look very different from the muscle cells needed for body movement. The structure of the heart reflects its job of pumping blood throughout the body, while the structure of the lungs maximizes the efficiency with which they can take up oxygen and release carbon dioxide. As we saw above, every organ is made up of two or more tissues, groups of similar cells that work together to perform a specific task. Humans--and other larger multicellular animals--are made up of four basic tissue types: epithelial tissue, connective tissue, muscle tissue, and nervous tissue. Epithelial tissue consists of tightly packed sheets of cells that cover surfaces--including the outside of the body--and line body cavities. For instance, the outer layer of your skin is an epithelial tissue, and so is the lining of your small intestine. Epithelial cells are polarized, meaning that they have a top and a bottom side. The apical, top, side of an epithelial cell faces the inside of a cavity or the outside of a structure and is usually exposed to fluid or air. The basal, bottom, side faces the underlying cells. For instance, the apical sides of intestinal cells have finger-like structures that increase surface area for absorbing nutrients. Epithelial cells are tightly packed, and this lets them act as barriers to the movement of fluids and potentially harmful microbes. Often, the cells are joined by specialized junctions that hold them tightly together to reduce leaks. Connective tissue consists of cells suspended in an extracellular matrix. In most cases, the matrix is made up of protein fibers like collagen and fibrin in a solid, liquid, or jellylike ground substance. Connective tissue supports and, as the name suggests, connects other tissues. Loose connective tissue, show below, is the most common type of connective tissue. It's found throughout your body, and it supports organs and blood vessels and links epithelial tissues to the muscles underneath. Dense, or fibrous, connective tissue is found in tendons and ligaments, which connect muscles to bones and bones to each other, respectively. Specialized forms of connective tissue include adipose tissue--body fat--bone, cartilage, and blood, in which the extracellular matrix is a liquid called plasma. Muscle tissue is essential for keeping the body upright, allowing it to move, and even pumping blood and pushing food through the digestive tract. Muscle cells, often called muscle fibers, contain the proteins actin and myosin, which allow them to contract. There are three main types of muscle: skeletal muscle, cardiac muscle, and smooth muscle. Skeletal muscle, which is also called striated--striped--muscle, is what we refer to as muscle in everyday life. Skeletal muscle is attached to bones by tendons, and it allows you to consciously control your movements. For instance, that quads in your legs or biceps in your arms are skeletal muscle. Cardiac muscle is found only in the walls of the heart. Like skeletal muscle, cardiac muscle is striated, or striped. But it's not under voluntary control, so--thankfully!--you don't need to think about making your heart beat. The individual fibers are connected by structures called intercalated disks, which allow them to contract in sync. Smooth muscle is found in the walls of blood vessels, as well as in the walls of the digestive tract, the uterus, the urinary bladder, and various other internal structures. Smooth muscle is not striped, striated, and it's involuntary, not under conscious control. That means you don't have to think about moving food through your digestive tract! Nervous tissue is involved in sensing stimuli--external or internal cues--and processing and transmitting information. It consists of two main types of cells: neurons, or nerve cells, and glia. The neurons are the basic functional unit of the nervous system. They generate electrical signals called conducted nerve impulses or action potentials that allow the neurons to convey information very rapidly across long distances. The glia mainly act to support neuronal function. Organs, such as the heart, the lungs, the stomach, the kidneys, the skin, and the liver, are made up of two or more types of tissue organized to serve a particular function. For example, the heart pumps blood, the lungs bring in oxygen and eliminate carbon dioxide, and the skin provides a barrier to protect internal structures from the external environment. Most organs contain all four tissue types. The layered walls of the small intestine provide a good example of how tissues form an organ. The inside of the intestine is lined by epithelial cells, some of which secrete hormones or digestive enzymes and others of which absorb nutrients. Around the epithelial layer are layers of connective tissue and smooth muscle, interspersed with glands, blood vessels, and neurons. The smooth muscle contracts to move food through the gut, under control of its associated networks of neurons. Organs are grouped into organ systems, in which they work together to carry out a particular function for the organism. For example, the heart and the blood vessels make up the cardiovascular system. They work together to circulate the blood, bringing oxygen and nutrients to cells throughout the body and carrying away carbon dioxide and metabolic wastes. Another example is the respiratory system, which brings oxygen into the body and gets rid of carbon dioxide. It includes the nose, mouth, pharynx, larynx, trachea, and lungs. Cardiovascular system involves the heart, blood, and blood vessels and it transports oxygen, nutrients, and other substances to the cells and transports wastes, carbon dioxide, and other substances away from the cells; it can also help stabilize body temperature and pH. Lymphatic system involves the lymph, lymph nodes, and lymph vessels and it defends against infection and disease and transfers lymph between tissues and the blood stream. Digestive system involves the mouth, salivary glands, esophagus, stomach, liver, gallbladder, exocrine pancreas, small intestine, and large intestine and it processes foods and absorbs nutrients, minerals, vitamins, and water. Endocrine system involves the pituitary, pineal, thyroid, parathyroids, endocrine pancreas, adrenals, testes, and ovaries and it provides communicates within the body via hormones and direct long-term change in other organ systems to maintain homeostasis. Integumentary system involves the skin, hair, and nails and provides protection from injury and fluid loss and provides physical defense against infection by microorganisms; involved in temperature control. Muscular system involves the skeletal, cardiac, and smooth muscles and provides movement, support, and heat production. Nervous system involves the brain, spinal cord, nerves, and sensory organs--eyes, ears, tongue, skin, and nose--and it collects, transfers, and processes information and directs short-term change in other organ systems. Reproductive system involves the fallopian tubes, uterus, vagina, ovaries, mammary glands (female), testes, vas deferens, seminal vesicles, prostate, and penis (male) and it produces gametes--sex cells--and sex hormones; ultimately produces offspring. Respiratory system involves the mouth, nose, pharynx, larynx, trachea, bronchi, lungs, and diaphragm and it delivers air to sites where gas exchange can occur. Skeletal system involves bones, cartilage, joints, tends, and ligaments and it supports and protects soft tissues of the body; provides movement at joints; produces blood cells; and stores minerals. Urinary system involves kidneys, uterus, urinary bladder, and urethra and it removes excess water, salts, and waste products from the blood and body and controls pH. Immune system involves leukocytes, tonsils, adenoids, thymus, and spleen and defends against microbial pathogens--disease-causing agents--and other diseases. Although we often talk about the different organ systems as though they were distinct, parts of one system may play a role in another system. The mouth, for instance, belongs to both the respiratory system and the digestive system. There's also a lot of functional overlap among the different systems. For instance, while we tend to think of the cardiovascular system as delivering oxygen and nutrients to cells, it also plays a role in maintaining temperature. The blood also transports hormones produced by the glands of the endocrine system, and white blood cells are a key component of the immune system. Just like workers on an assembly line, the organs of an organ system must work together for the system to function as a whole. For instance, the function of the digestive system--taking in food, breaking it down into molecules small enough to be absorbed, absorbing it, and eliminating undigested waste products--depends on each successive organ doing its individual job. Digestion is the breakdown of food so that its nutrients can be absorbed. It includes both mechanical digestion and chemical digestion. In mechanical digestion, chunks of food are broken into smaller pieces. In chemical digestion, large molecules like proteins and starches are broken into simpler units that can be readily absorbed. Mechanical digestion, along with some initial chemical digestion, takes place in the mouth and stomach. Chewing breaks food into smaller pieces, and the stomach churns the food up into a fluid mixture. The stomach also acts as a storage tank, releasing partially digested food into the small intestine at a rate the small intestine can handle. The small intestine is the major site of chemical digestion, which is carried out by enzymes released from the pancreas and liver. The small intestine is also the main site of nutrient absorption; molecules like sugars and amino acids are taken up by cells and transported into the bloodstream for use. The mouth, stomach, small intestine, and other digestive system organs work together to make digesting food and absorbing nutrients efficient. Digestion wouldn't work so well if your stomach stopped churning or if one of your enzyme-producing glands--like the pancreas--decided to take the day off! Just as the organs in an organ system work together to accomplish their task, so the different organ systems also cooperate to keep the body running. For example, the respiratory system and the circulatory system work closely together to deliver oxygen to cells and to get rid of the carbon dioxide the cells produce. The circulatory system picks up oxygen in the lungs and drops it off in the tissues, then performs the reverse service for carbon dioxide. The lungs expel the carbon dioxide and bring in new oxygen-containing air. Only when both systems are working together can oxygen and carbon dioxide be successfully exchanged between cells and environment. There are many other examples of this cooperation in your body. For instance, the blood in your circulatory system has to receive nutrients from your digestive system and undergo filtration in your kidneys, or it wouldn't be able to sustain the cells of your body and remove the wastes they produce. Many body functions are controlled by the nervous system and the endocrine system. These two regulatory systems use chemical messengers to affect the function of the other organ systems and to coordinate activity at different locations in the body. How do the endocrine and nervous systems differ? - In the endocrine system, the chemical messengers are hormones released into the blood. - In the nervous system, the chemical messengers are neurotransmitters sent straight from one cell to another across a tiny gap. Since hormones have to travel through the bloodstream to their targets, the endocrine system usually coordinates processes on a slower time scale than the nervous system in which messages are delivered directly to the target cell. In some cases, such as the fight-or-flight response to an acute threat, the nervous and endocrine systems work together to produce a response.

SMR 3.4.a: Demonstrate knowledge of the roles of DNA (deoxyribonucleic acid) molecules in cells (e.g., storing genetic information, coding for proteins, regulatory functions, structural functions).

Nucleic acids, and DNA in particular, are key macromolecules for the continuity of life. DNA bears the hereditary information that's passed on from parents to children, providing instructions for how (and when) to make the many proteins needed to build and maintain functioning cells, tissues, and organisms. How DNA carries this information, and how it is put into action by cells and organisms, is complex, fascinating, and fairly mind-blowing, and we'll explore it in more detail in the section on molecular biology. Here, we'll just take a quick look at nucleic acids from the macromolecule perspective. Nucleic acids, macromolecules made out of units called nucleotides, come in two naturally occurring varieties: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). DNA is the genetic material found in living organisms, all the way from single-celled bacteria to multicellular mammals like you and me. Some viruses use RNA, not DNA, as their genetic material, but aren't technically considered to be alive (since they cannot reproduce without help from a host). In eukaryotes, such as plants and animals, DNA is found in the nucleus, a specialized, membrane-bound vault in the cell, as well as in certain other types of organelles (such as mitochondria and the chloroplasts of plants). In prokaryotes, such as bacteria, the DNA is not enclosed in a membranous envelope, although it's located in a specialized cell region called the nucleoid. In eukaryotes, DNA is typically broken up into a number of very long, linear pieces called chromosomes, while in prokaryotes such as bacteria, chromosomes are much smaller and often circular (ring-shaped). A chromosome may contain tens of thousands of genes, each providing instructions on how to make a particular product needed by the cell. Many genes encode protein products, meaning that they specify the sequence of amino acids used to build a particular protein. Before this information can be used for protein synthesis, however, an RNA copy (transcript) of the gene must first be made. This type of RNA is called a messenger RNA (mRNA), as it serves as a messenger between DNA and the ribosomes, molecular machines that read mRNA sequences and use them to build proteins. This progression from DNA to RNA to protein is called the "central dogma" of molecular biology. Importantly, not all genes encode protein products. For instance, some genes specify ribosomal RNAs (rRNAs), which serve as structural components of ribosomes, or transfer RNAs (tRNAs), cloverleaf-shaped RNA molecules that bring amino acids to the ribosome for protein synthesis. Still other RNA molecules, such as tiny microRNAs (miRNAs), act as regulators of other genes, and new types of non-protein-coding RNAs are being discovered all the time. DNA and RNA are polymers (in the case of DNA, often very long polymers), and are made up of monomers known as nucleotides. When these monomers combine, the resulting chain is called a polynucleotide (poly- = "many"). Each nucleotide is made up of three parts: a nitrogen-containing ring structure called a nitrogenous base, a five-carbon sugar, and at least one phosphate group. The sugar molecule has a central position in the nucleotide, with the base attached to one of its carbons and the phosphate group (or groups) attached to another. Let's look at each part of a nucleotide in turn. The nitrogenous bases of nucleotides are organic (carbon-based) molecules made up of nitrogen-containing ring structures. Each nucleotide in DNA contains one of four possible nitrogenous bases: adenine (A), guanine (G) cytosine (C), and thymine (T). Adenine and guanine are purines, meaning that their structures contain two fused carbon-nitrogen rings. Cytosine and thymine, in contrast, are pyrimidines and have a single carbon-nitrogen ring. RNA nucleotides may also bear adenine, guanine and cytosine bases, but instead of thymine they have another pyrimidine base called uracil (U). As shown in the figure above, each base has a unique structure, with its own set of functional groups attached to the ring structure. In molecular biology shorthand, the nitrogenous bases are often just referred to by their one-letter symbols, A, T, G, C, and U. DNA contains A, T, G, and C, while RNA contains A, U, G, and C (that is, U is swapped in for T). In addition to having slightly different sets of bases, DNA and RNA nucleotides also have slightly different sugars. The five-carbon sugar in DNA is called deoxyribose, while in RNA, the sugar is ribose. These two are very similar in structure, with just one difference: the second carbon of ribose bears a hydroxyl group, while the equivalent carbon of deoxyribose has a hydrogen instead. The carbon atoms of a nucleotide's sugar molecule are numbered as 1′, 2′, 3′, 4′, and 5′ (1′ is read as "one prime"), as shown in the figure above. In a nucleotide, the sugar occupies a central position, with the base attached to its 1′ carbon and the phosphate group (or groups) attached to its 5′ carbon. Nucleotides may have a single phosphate group, or a chain of up to three phosphate groups, attached to the 5' carbon of the sugar. Some chemistry sources use the term "nucleotide" only for the single-phosphate case, but in molecular biology, the broader definition is generally accepted. In a cell, a nucleotide about to be added to the end of a polynucleotide chain will bear a series of three phosphate groups. When the nucleotide joins the growing DNA or RNA chain, it loses two phosphate groups. So, in a chain of DNA or RNA, each nucleotide has just one phosphate group. A consequence of the structure of nucleotides is that a polynucleotide chain has directionality--that is, it has two ends that are different from each other. At the 5' end, or beginning, of the chain, the 5' phosphate group of the first nucleotide in the chain sticks out. At the other end, called the 3' end, the 3' hydroxyl of the last nucleotide added to the chain is exposed. DNA sequences are usually written in the 5' to 3' direction, meaning that the nucleotide at the 5' end comes first and the nucleotide at the 3' end comes last. As new nucleotides are added to a strand of DNA or RNA, the strand grows at its 3' end, with the 5′ phosphate of an incoming nucleotide attaching to the hydroxyl group at the 3' end of the chain. This makes a chain with each sugar joined to its neighbors by a set of bonds called a phosphodiester linkage. Deoxyribonucleic acid, or DNA, chains are typically found in a double helix, a structure in which two matching (complementary) chains are stuck together, as shown in the diagram at left. The sugars and phosphates lie on the outside of the helix, forming the backbone of the DNA; this portion of the molecule is sometimes called the sugar-phosphate backbone. The nitrogenous bases extend into the interior, like the steps of a staircase, in pairs; the bases of a pair are bound to each other by hydrogen bonds. The two strands of the helix run in opposite directions, meaning that the 5′ end of one strand is paired up with the 3′ end of its matching strand. (This is referred to as antiparallel orientation and is important for the copying of DNA.) So, can any two bases decide to get together and form a pair in the double helix? The answer is a definite no. Because of the sizes and functional groups of the bases, base pairing is highly specific: A can only pair with T, and G can only pair with C, as shown below. This means that the two strands of a DNA double helix have a very predictable relationship to each other. For instance, if you know that the sequence of one strand is 5'-AATTGGCC-3', the complementary strand must have the sequence 3'-TTAACCGG-5'. This allows each base to match up with its partner. When two DNA sequences match in this way, such that they can stick to each other in an antiparallel fashion and form a helix, they are said to be complementary. Ribonucleic acid (RNA), unlike DNA, is usually single-stranded. A nucleotide in an RNA chain will contain ribose (the five-carbon sugar), one of the four nitrogenous bases (A, U, G, or C), and a phosphate group. Here, we'll take a look at four major types of RNA: messenger RNA (mRNA), ribosomal RNA (rRNA), transfer RNA (tRNA), and regulatory RNAs. Messenger RNA (mRNA) is an intermediate between a protein-coding gene and its protein product. If a cell needs to make a particular protein, the gene encoding the protein will be turned "on," meaning an RNA-polymerizing enzyme will come and make an RNA copy, or transcript, of the gene's DNA sequence. The transcript carries the same information as the DNA sequence of its gene. However, in the RNA molecule, the base T is replaced with U. For instance, if a DNA coding strand has the sequence 5'-AATTGCGC-3', the sequence of the corresponding RNA will be 5'-AAUUGCGC-3'. Once an mRNA has been produced, it will associate with a ribosome, a molecular machine that specializes in assembling proteins out of amino acids. The ribosome uses the information in the mRNA to make a protein of a specific sequence, "reading out" the mRNA's nucleotides in groups of three (called codons) and adding a particular amino acid for each codon. Ribosomal RNA (rRNA) is a major component of ribosomes, where it helps mRNA bind in the right spot so its sequence information can be read out. Some rRNAs also act as enzymes, meaning that they help accelerate (catalyze) chemical reactions - in this case, the formation of bonds that link amino acids to form a protein. RNAs that act as enzymes are known as ribozymes. Transfer RNAs (tRNAs) are also involved in protein synthesis, but their job is to act as carriers--to bring amino acids to the ribosome, ensuring that the amino acid added to the chain is the one specified by the mRNA. Transfer RNAs consist of a single strand of RNA, but this strand has complementary segments that stick together to make double-stranded regions. This base-pairing creates a complex 3D structure important to the function of the molecule. Some types of non-coding RNAs (RNAs that do not encode proteins) help regulate the expression of other genes. Such RNAs may be called regulatory RNAs. For example, microRNAs (miRNAs) and small interfering RNAs siRNAs are small regulatory RNA molecules about 22 nucleotides long. They bind to specific mRNA molecules (with partly or fully complementary sequences) and reduce their stability or interfere with their translation, providing a way for the cell to decrease or fine-tune levels of these mRNAs. These are just some examples out of many types of noncoding and regulatory RNAs. Scientists are still discovering new varieties of noncoding RNA. DNA: Function - Repository of genetic information. Sugar - Deoxyribose Structure - Double helix Bases - C, T, A, G RNA: Function - Involved in protein synthesis and gene regulation; carrier of genetic information in some viruses Sugar - Ribose Structure - Usually single-stranded Bases - C, U, A, G

SMR 2.5.a: Demonstrate knowledge of kinetic and potential energy.

Potential energy is the energy stored in an object due to its position. Kinetic energy is the energy a moving object has due to its motion. Kinetic energy is the energy of motion. Anytime matter is in motion, it has kinetic energy. KE = 1/2 mv^2 SI unit = Joule (J) The faster an object moves, the more kinetic energy it has. The more mass an object has, the more kinetic energy it has. According to the equation above, velocity affects kinetic energy more than mass. Potential energy is called the energy of position. Gravitational potential energy is energy that is dependent on height. PE = mgh Potential energy can be found in energy sources, too, such as fossil fuels, food, and batteries. http://www.csun.edu/~psk17793/S9CP/S9%20potential_and_kinetic_energy.htm#:~:text=Energy%20stored%20in%20an%20object%20due%20to%20its%20position%20is%20Potential%20Energy.&text=Energy%20that%20a%20moving%20object,its%20motion%20is%20Kinetic%20Energy.

SMR 2.4.c: Demonstrate knowledge of resonance and of the reflection, refraction, and transmission of waves.

We already know that waves originate from vibrations. Sound waves come from mechanical vibrations in solids, liquids, and gases. Light waves come from the vibration of charged particles. Objects, charged particles, and mechanical systems usually have a certain frequency at which they tend to vibrate. This is called their resonant frequency, or their natural frequency. Some objects have two or more resonant frequencies. You know when you drive on a bumpy road and your car begins to bounce up and down? Your car is oscillating at its resonant frequency; or really, the resonant frequency of the shock absorbers. You may notice that when you're riding in a bus, the bouncing frequency is a little bit slower. That's because the bus's shock absorbers have a lower resonant frequency. When a sound or light wave strikes an object, it is already vibrating at some particular frequency. If that frequency happens to match the resonant frequency of the object it's hitting, then you'll get what's called resonance. Resonance occurs when the amplitude of an object's oscillations are increased by the matching vibrations of another object. Let's take a typical light wave. We'll say it's a stream of white light that comes from the sun. And, let's take a dark object, like a western rat snake slithering through your yard. The molecules in the snake's skin have a set of resonant frequencies. That is, the electrons in the atoms tend to vibrate at certain frequencies. The light coming down from the sun is white light. So, it has not just one but many wave frequencies. It has frequencies of red and green, blue and yellow, orange and violet. Each of these frequencies strikes the snake's skin. And, each frequency makes a different electron vibrate. The yellow frequency resonates with the electrons whose resonant frequency is yellow. The blue frequency resonates with the electrons whose resonant frequency is blue. So, the snake's skin, as a whole, resonates with the sunlight. When light waves resonate with an object, they cause the electrons to vibrate with high amplitudes. The light energy is absorbed by the object, and we don't see that light coming back to us at all. The object appears black. Since a western rat snake absorbs all the frequencies of sunlight, then it appears as a black snake. What if an object does not absorb any of the sunlight? What if none of its electrons resonate with the light frequencies? If resonance does not occur, then what you'll get is transmission, the passing of light waves through an object. The light still causes vibrations of the electrons. But, because it doesn't match the electrons' resonant frequencies, the vibrations are very small and they pass from atom to atom all the way through the object. An object with no resonance would exhibit zero absorption and 100% transmission. So, the object, in this case, wouldn't be white; it would be clear, like glass or water. Reflection - Reflection is the phenomenon in which light reflects back after striking a smooth surface. In reflection, the ray which strikes the smooth surface is called the incident ray. The ray which reflects back from a smooth surface is called a reflected ray. The angle in between the incident ray and the normal ray is called the angle of incidence and the angle between the normal ray and reflected ray is called the angle of reflection. Refraction - Refraction is the process in which, when the incidence ray strikes the surface in some medium, and it gets diverted or bent while passing through another medium. The ray generally bends towards the normal ray while traveling to a rarer medium to a denser medium and it bends away from normal ray while traveling to denser to rarer medium. Characteristics of reflection: - Reflection is the bouncing back of light when it strikes the smooth surface. - The phenomenon of reflection generally occurs in a mirror. - Reflection is the phenomenon that sends back the light in the same medium. The medium doesn't change. - According to the law of reflection, the angle of incidence is equal to the angle of reflection. - There are generally two types of reflections: 1. regular reflection (specular reflection) and 2. diffused reflection. Characteristics of refraction: - Refraction is the bending of light when it travels from one medium to another. - The phenomenon of refraction generally occurs in lenses. - Refraction is the phenomenon that sends back the light in a different medium. The medium changes. - According to the law of refraction of light, the ratio of the sine of the angle of incidence and sine of the angle of refraction is constant. - There are single types of refraction. https://www.vnaya.com/difference-between-reflection-and-refraction/#:~:text=Reflection%20is%20the%20bouncing%20back,from%20one%20medium%20to%20another%20.

SMR 2.4.h: Demonstrate knowledge of how energy and information are transferred by waves without mass transfer, including recognizing technology that employs this phenomenon.

All waves transport energy without permanently displacing the medium through which they are travel. Instead, waves travel through oscillations or vibrations around fixed locations. For example, a boat resting on a lake or ocean is bobbing up and down as the waves travel, but the boat stays primarily in the same location. This is how the matter itself is. The matter stays primarily in the same location as the particles vibrates or oscillate through the medium. http://sciencecsetprep.weebly.com/waves.html

SMR 2.2.a: Recognize that chemical reactions can be understood in terms of the collisions between ions, atoms, or molecules and the rearrangement of particles.

For a chemical change to occur, the chemical bonds must be altered. Valence electrons are involved in the formation or breaking of bonds. Collision theory is how scientists make predictions about how fast chemical reactions take place. Chemical reactions occur when particles are oriented correctly and collide with enough energy to break bonds. Reaction rates are how fast chemical reactions occur and are impacted by several factors, including the number of particles, the temperature, the pressure, the presence of a catalyst, and the size of the particles. Collision theory states that the number of successful or effective collisions is related to the reaction rate. The more successful collisions, the faster the reaction rate. This theory helps scientists determine reaction rates mathematically. Formed substances are 'produced' from the reaction, the molecules you get in the end are called products. Products are physically different from the reactants you started with, but they have also undergone permanent chemical changes as well. So if you can't undo the change, you've likely got a chemical reaction on your hands, not just a physical change. https://quizlet.com/546231477/final-study-guide-cset-i-study-guide-flash-cards/

SMR 1.2.c: Apply knowledge of the roles of models (e.g., mathematical, physical, computer simulations) in the engineering design process.

Mathematical models and/or computer simulations are used to predict the effects of a design solution on systems and/or the interactions between systems. Physical, mathematical, and computer models can be used to simulate systems and interactions. From NGSS SEPs: - Use mathematical models and/or computer simulations to predict the effects of a design solution on systems and/or the interactions between systems. From NGSS DCIs: - Both physical models and computers can be used in various ways to aid in the engineering design process. Computers are useful for a variety of purposes, such as running simulations to test different ways of solving a problem or to see which one is most efficient or economical; and in making a persuasive presentation to a client about how a given design will meet his or her needs. From NGSS CCs: - Models (e.g., physical, mathematical, computer models) can be used to simulate systems and interactions--including energy, matter, and information flows--within and between systems at different scales. https://www.nextgenscience.org/pe/hs-ets1-4-engineering-design

SMR 3.2.d: Demonstrate knowledge of the major anatomical structures and life processes (e.g., reproduction, photosynthesis, cellular respiration, transpiration) of various plant groups.

Reproduction: - Reproductive systems are most often in the form of flowers, although other types of reproduction are used by some plants; spores are a reproductive method of some non-flowering plants. - These methods contain the biological materials needed for propagation and growth of a new plant. Photosynthesis: - Plants are organisms that make their own food, a simple sugar, for survival. - The process by which they make this sugar is called photosynthesis. - Plant cells require sunlight, carbon dioxide, and water to undergo photosynthesis. - Chloroplasts, found in the cells of the leaf, contain chlorophyll, a green pigment that absorbs light energy from the sun. - Carbon dioxide is taken in through openings, or pores, in the leaf called stomata and water is absorbed through the roots. - Simple sugar (glucose) and oxygen gas are produced. The plant uses the glucose for food and the oxygen gas is released into the air through the stomata. - Photosynthesis provides the oxygen gas in the atmosphere that most living organisms need. - The chemical equation for photosynthesis is 6CO2 + 6H2O + energy --> C6H12O6 + 6O2. Cellular respiration: - The glucose created through photosynthesis is used to provide energy needed by the plants to perform life functions such as growing and repairing. - To obtain the energy from the food it produces, plants must break down the sugar in the cells throughout the plant in a cellular process called respiration. - Cells require glucose and oxygen gas to undergo respiration. - Oxygen gas from the air (taken in through the stomata) combines with the glucose, which is then broken down producing carbon dioxide and water. - During this process, energy is released. This energy will be used by the plant to perform life functions such as growth and repair. - The carbon dioxide gas and water that are formed are then given off through the stomata in the leaves. - All organisms undergo respiration to release energy from food. - The chemical equation for respiration is C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy. - Photosynthesis and respiration are chemical reactions that have chemical equations. - The reactants are at the beginning of the reaction (left side of the arrow) and the products are the substances that are formed (right side of the arrow). Transpiration: - Some of the water taken in through the roots of the plants is used in the process of photosynthesis. - Plants lose water through the leaves. This process is called transpiration. - Without a way to control transpiration, plants would wither up and die. - Guard cells, mostly on the underside of the leaf, open and close the stomata and allow plants to control transpiration. - When the stomata are closed, water cannot escape from the leaf.

SMR 2.3.d: Analyze displacement, motion, and forces using models (e.g., vector, graphic representation, equations).

A vector diagram depicts an arrow drawn to scale that points in a specific direction. The vector arrow has a head and a tail. The direction of a vector is expressed in angles of rotation of the vector about its tail. The magnitude of the vector is expressed in the scaled length of the arrow. http://sciencecsetprep.weebly.com/forces-and-motions.html

SMR 3.4.g: Apply knowledge of genotypes and phenotypes and the inheritance of traits that are determined by one or more genes (e.g., dominant, recessive, and sex-linked alleles; incomplete dominance).

Gregor Mendel knew how to keep things simple. In Mendel's work on pea plants, each gene came in just two different versions, or alleles, and these alleles had a nice, clear-cut dominance relationship (with the dominant allele fully overriding the recessive allele to determine the plant's appearance). Today, we know that not all alleles behave quite as straightforwardly as in Mendel's experiments. For example, in real life: - Allele pairs may have a variety of dominance relationships (that is, one allele of the pair may not completely "hide" the other in the heterozygote). - There are often many different alleles of a gene in a population. In these cases, an organism's genotype, or set of alleles, still determines its phenotype, or observable features. However, a variety of alleles may interact with one another in different ways to specify phenotype. As a side note, we're probably lucky that Mendel's pea genes didn't show these complexities. If they had, it's possible that Mendel would not have understood his results, and wouldn't have figured out the core principles of inheritance--which are key in helping us understand the special cases! Mendel's results were groundbreaking partly because they contradicted the (then-popular) idea that parents' traits were permanently blended in their offspring. In some cases, however, the phenotype of a heterozygous organism can actually be a blend between the phenotypes of its homozygous parents. For example, in the snapdragon, Antirrhinum majus, a cross between a homozygous white-flowered plant (C^W, C^W) and a homozygous red-flowered plant (C^R, C^R) will produce offspring with pink flowers (C^R, C^W). This type of relationship between alleles, with a heterozygote phenotype intermediate between the two homozygote phenotypes, is called incomplete dominance. We can still use Mendel's model to predict the results of crosses for alleles that show incomplete dominance. For example, self-fertilization of a pink plant would produce a genotype ratio of 1 C^R, C^R : 2 C^R, C^W : 1 C^W, C^W and a phenotype ratio of 1 : 2 : 1 red : pink : white. Alleles are still inherited according to Mendel's basic rules, even when they show incomplete dominance. Closely related to incomplete dominance is codominance, in which both alleles are simultaneously expressed in the heterozygote. We can see an example of codominance in the MN blood groups of humans (less famous than the ABO blood groups, but still important!). A person's MN blood type is determined by his or her alleles of a certain gene. An L^M allele specifies production of an M marker displayed on the surface of red blood cells, while an L^N allele specifies production of a slightly different N marker. Homozygotes (L^M, L^M and L^N, L^N) have only M or an N markers, respectively, on the surface of their red blood cells. However, heterozygotes (L^M, L^N) have both types of markers in equal numbers on the cell surface. As for incomplete dominance, we can still use Mendel's rules to predict inheritance of codominant alleles. For example, if two people with L^M, L^N genotypes had children, we would expect to see M, MN, and N blood types and L^M, L^M, L^M, L^N, and L^N, L^N genotypes in their children in a 1 : 2: 1 ratio (if they had enough children for us to determine ratios accurately!) Mendel's work suggested that just two alleles existed for each gene. Today, we know that's not always, or even usually, the case! Although individual humans (and all diploid organisms) can only have two alleles for a given gene, multiple alleles may exist in a population level, and different individuals in the population may have different pairs of these alleles. As an example, let's consider a gene that specifies coat color in rabbits, called the C gene. The C gene comes in four common alleles: C, c^ch, c^h, and c: - A CC rabbit has black or brown fur - A c^ch,c^ch rabbit has chinchilla coloration (grayish fur) - A c^h,c^h rabbit has Himalayan (color-point) patterning, with a white body and dark ears, face, feet, and tail - A cc rabbit is albino with a pure white coat Multiple alleles makes for many possible dominance relationship. In this case, the black C allele is completely dominant to all the others; the chinchilla c^ch allele is incompletely dominant to the Himalayan c^h and albino c alleles; and the Himalayan c^h allele is completely dominant to the albino c allele. Rabbit breeders figured out these relationships by crossing different rabbits of different genotypes and observing the phenotypes of the heterozygous kits (baby bunnies). The basic principles of Gregor Mendel's model of inheritance have held up for over a century. They can explain how many different characteristics are inherited, in a wide range of organisms including human beings. Some of the key elements of Mendel's original model were: 1. Heritable traits are determined by heritable factors, now called genes. Genes come in pairs (that is, are present in two copies in an organism). 2. Genes come in different versions, now called alleles. When an organism has two different alleles of a gene, one (the dominant allele) will hide the presence of the other (the recessive allele) and determine appearance. 3. During gamete production, each egg or sperm cell receives just one of the two gene copies present in the organism, and the copy allocated to each gamete is random (law of segregation). 4. Genes for different traits are inherited independently of one another (law of independent assortment). These rules still form the foundation of our understanding of inheritance--that is, how traits are passed on and how an organism's genotype (set of alleles) determines its phenotype (observable features). However, we now know of some exceptions, extensions, and variations, which must be added to the model in order to fully explain the inheritance patterns we see around us. Some of the variations on Mendel's rules involve single genes. These include: - Multiple alleles. Mendel studied just two alleles of his pea genes, but real populations often have multiple alleles of a given gene. - Incomplete dominance. Two alleles may produce an intermediate phenotype when both are present, rather than one fully determining the phenotype. - Codominance. Two alleles may be simultaneously expressed when both are present, rather than one fully determining the phenotype. - Pleiotropy. Some genes affect many different characteristics, not just a single characteristic. - Lethal alleles. Some genes have alleles that prevent survival when homozygous or heterozygous. - Sex linkage. Genes carried on sex chromosomes, such as the X chromosome of humans, show different inheritance patterns than genes on autosomal (non-sex) chromosomes. Other variations on Mendel's rules involve interactions between pairs (or, potentially, larger numbers) of genes. Many characteristics are controlled by more than one gene, and when two genes affect the same process, they can interact with each other in a variety of different ways. For example: - Complementary genes. Recessive alleles of two different genes may give the same phenotype. - Epistasis. The alleles of one gene may mask or conceal the alleles of another gene. In addition, some gene pairs lie near one another on a chromosome and are genetically linked, meaning that they don't assort independently. Many characteristics important in our everyday lives, such as height, skin color, eye color, and risk of diseases like diabetes, are controlled by many factors. These factors may be genetic, environmental, or both. - Polygenic inheritance. Some characteristics are polygenic, meaning that they're controlled by a number of different genes. In polygenic inheritance, traits often form a phenotypic spectrum rather than falling into clear-cut categories. - Environmental effects. Most real-world characteristics are determined not just by genotype, but also by environmental factors that influence how genotype is translated into phenotype. Genetic background and environment contribute to incomplete penetrance, in which not all individuals with a genotype display a corresponding phenotype, and variable expressivity, in which individuals of a particular genotype may have stronger or weaker versions of a phenotype.

SMR 3.4.c: Apply knowledge of how genetic variation may be the result of errors that occur during DNA replication or mutations caused by environmental factors and explain their causes and effects.

Over a lifetime, our DNA can undergo changes or mutations in the sequence of bases: A, C, G and T. This results in changes in the proteins that are made. This can be a bad or a good thing. A mutation is a change that occurs in our DNA sequence, either due to mistakes when the DNA is copied or as the result of environmental factors such as UV light and cigarette smoke. Mutations can occur during DNA replication if errors are made and not corrected in time. Mutations can also occur as the result of exposure to environmental factors such as smoking, sunlight and radiation. Often cells can recognize any potentially mutation-causing damage and repair it before it becomes a fixed mutation. Mutations contribute to genetic variation within species. Mutations can also be inherited, particularly if they have a positive effect. For example, the disorder sickle cell anemia is caused by a mutation in the gene that instructs the building of a protein called hemoglobin. This causes the red blood cells to become an abnormal, rigid, sickle shape. However, in African populations, having this mutation also protects against malaria. However, mutation can also disrupt normal gene activity and cause diseases, like cancer. Cancer is the most common human genetic disease; it is caused by mutations occurring in a number of growth-controlling genes. Sometimes faulty, cancer-causing genes can exist from birth, increasing a person's chance of getting cancer. Let's begin with a question: What is a gene mutation and how do mutations occur? A gene mutation is a permanent alteration in the DNA sequence that makes up a gene, such that the sequence differs from what is found in most people. Mutations range in size; they can affect anywhere from a single DNA building block (base pair) to a large segment of a chromosome that includes multiple genes. Gene mutations can be classified in two major ways: - HEREDITARY MUTATIONS are inherited from a parent and are present throughout a person's life in virtually every cell in the body. These mutations are also called germline mutations because they are present in the parent's egg or sperm cells, which are also called germ cells. When an egg and a sperm cell unite, the resulting fertilized egg cell receives DNA from both parents. If this DNA has a mutation, the child that grows from the fertilized egg will have the mutation in each of his or her cells. - ACQUIRED (OR SOMATIC) MUTATIONS occur at some time during a person's life and are present only in certain cells, not in every cell in the body. These changes can be caused by environmental factors such as ultraviolet radiation from the sun, or can occur if a mistake is made as DNA copies itself during cell division. Acquired mutations in somatic cells (cells other than sperm and egg cells) cannot be passed on to the next generation. Genetic changes that are described as de novo (new) mutations can be either hereditary or somatic. In some cases, the mutation occurs in a person's egg or sperm cell but is not present in any of the person's other cells. In other cases, the mutation occurs in the fertilized egg shortly after the egg and sperm cells unite. (It is often impossible to tell exactly when a de novo mutation happened.) As the fertilized egg divides, each resulting cell in the growing embryo will have the mutation. De novo mutations may explain genetic disorders in which an affected child has a mutation in every cell in the body but the parents do not, and there is no family history of the disorder. Somatic mutations that happen in a single cell early in embryonic development can lead to a situation called mosaicism. These genetic changes are not present in a parent's egg or sperm cells, or in the fertilized egg, but happen a bit later when the embryo includes several cells. As all the cells divide during growth and development, cells that arise from the cell with the altered gene will have the mutation, while other cells will not. Depending on the mutation and how many cells are affected, mosaicism may or may not cause health problems. Most disease-causing gene mutations are uncommon in the general population. However, other genetic changes occur more frequently. Genetic alterations that occur in more than 1 percent of the population are called polymorphisms. They are common enough to be considered a normal variation in the DNA. Polymorphisms are responsible for many of the normal differences between people such as eye color, hair color, and blood type. Although many polymorphisms have no negative effects on a person's health, some of these variations may influence the risk of developing certain disorders. A well-studied example of a mutation is seen in people suffering from xeroderma pigmentosa. Affected individuals have skin that is highly sensitive to UV rays from the sun. When individuals are exposed to UV, pyrimidine dimers, especially those of thymine, are formed; people with xeroderma pigmentosa are not able to repair the damage. These are not repaired because of a defect in the nucleotide excision repair enzymes, whereas in normal individuals, the thymine dimers are excised and the defect is corrected. The thymine dimers distort the structure of the DNA double helix, and this may cause problems during DNA replication. People with xeroderma pigmentosa may have a higher risk of contracting skin cancer than those who don't have the condition. Errors during DNA replication are not the only reason why mutations arise in DNA. Mutations, variations in the nucleotide sequence of a genome, can also occur because of damage to DNA. Such mutations may be of two types: induced or spontaneous. Induced mutations are those that result from an exposure to chemicals, UV rays, x-rays, or some other environmental agent. Spontaneous mutations occur without any exposure to any environmental agent; they are a result of natural reactions taking place within the body. Mutations may have a wide range of effects. Some mutations are not expressed; these are known as silent mutations. Point mutations are those mutations that affect a single base pair. The most common nucleotide mutations are substitutions, in which one base is replaced by another. These can be of two types, either transitions or transversions. Transition substitution refers to a purine or pyrimidine being replaced by a base of the same kind; for example, a purine such as adenine may be replaced by the purine guanine. Transversion substitution refers to a purine being replaced by a pyrimidine, or vice versa; for example, cytosine, a pyrimidine, is replaced by adenine, a purine. Mutations can also be the result of the addition of a base, known as an insertion, or the removal of a base, also known as deletion. Sometimes a piece of DNA from one chromosome may get moved to another chromosome or to another region of the same chromosome; this is also known as translocation. Mutations in repair genes have been known to cause cancer. Many mutated repair genes have been implicated in certain forms of pancreatic cancer, colon cancer, and colorectal cancer. Mutations can affect either somatic cells or germ cells. If many mutations accumulate in a somatic cell, they may lead to problems such as the uncontrolled cell division observed in cancer. If a mutation takes place in germ cells, the mutation will be passed on to the next generation, as in the case of hemophilia and xeroderma pigmentosa.

SMR 2.6.a: Demonstrate knowledge of electrostatic and magnetostatic phenomena, including evaluating examples of each type of phenomenon.

There are two types of electric charge: positive and negative. - The nucleus of an atom consists of neutral neutrons and positive protons, giving it an overall positive charge. - The electrons surrounding the nucleus are negatively charged. - An atom is neutral or without net charge if the number of electrons balances the number of protons in the nucleus. Electrons may be removed from a neutral atom, leaving the atom (now called an ion) with a net positive charge. Atoms may also acquire excess electrons and become negatively charged ions. Like charges repel, and opposite charges attract. Lessons in electrostatics invariably begin with demonstrations of ordinary objects being charged by friction and either attracting or repelling other objects, which have been polarized. Two balloons on strings are rubbed against a volunteer's hair. The friction of the rubbing draws electrons from the hair onto the surfaces of the balloons, because the material the balloon is made of has a greater affinity for electrons than the hair does. The balloons, which previously were neutral, each acquire a net negative charge from the negatively charged electrons. (The hair has a net positive charge, so the sum of the hair and balloon charges is zero.) If the balloons are suspended from one point by their strings they repel each other. This shows that like charges repel. Even as the balloon repel each other, however, they attract small pieces of paper. The paper has no overall charge, but the charged particles in the paper will move around or molecules will align themselves so that the paper becomes polarized, with a positive charge at one end and negative at the other. The positive charges in the paper are attracted to the negatively charged balloons: opposite charges attract. Eventually, if a balloon and piece of paper stick together, the paper falls off. Water vapor and other electrically polarized molecules in the surrounding air can remove excess charge. Charging by friction works best with two materials that have a different affinity for electrons. Polyester and rubber will draw electrons out of materials that have a lower affinity for electrons, such as silk, wool, and glass. Cotton and other natural fibers are not easily charged. A neutral object can be charged by touching it with a charged object. This is sometimes called charging by contact. For charging by conduction or contact to work, the initially neutral object must be insulated from ground. If it is not insulated, the charge it acquires from the charging object will just be neutralized. Charging by induction is like charging by conduction, except that the two objects never actually touch. The inductively charged object gets its charges through a grounding wire. In this example, electrons leave the grounded conductor through the grounding wire, leaving a positive charge. When the grounding wire is cut, the conductor remains positive, even when the original charged object is removed. The spark of static electricity is caused by a sudden electrostatic discharge. Our feet tend to draw electrons out of a carpet as we shuffle across it. Then, when we touch a metal object (such as a doorknob), the excess electrons flow between finger and doorknob. The brief current through a very small area of the body (the fingertip) is felt as a tingling sensation. We can reduce this "zap" by grasping a set of metal keys, then using the keys to touch the doorknob. This works because the keys make contact with a large area of the hand, which dilutes the tingling sensation. A good way to remove excess charge from your body before touching sensitive equipment is to touch a water faucet. The metal pipe acts as a ground or a limitless supply of balancing charge. Having hairy legs can cause more static electricity to build up than if the legs are shaved. Be safe: It is best not to get into or out of your vehicle while gas is being pumped--the static spark could ignite the fuel. Around 600 BCE, the Greek philosopher and mathematician Thales knew that rubbing a piece of amber (hardened tree sap) against wool or animal fur would cause it to attract light objects such as dust, pieces of straw, and feathers. Thales apparently mistook this case of electrostatic attraction for a certain kind of magnetism induced by friction. What he actually witnessed was the buildup of electrical charge on the amber, which then attracted the light objects by polarizing them. The attraction between rubbed amber and feathers appears similar to that between a lodestone and an iron nail. Not until the 17th century did scientists distinguish between the electrostatics and magnetism. Only a few elements can be magnetized: mainly, iron, cobalt, and nickel. However, almost any substance can be electrified or acquire a charge. A magnet always has at least two opposite poles, north and south, and its magnetic field is concentrated at these poles. However, an object may have just one electric charge, positive or negative. Materials that hold on to built-up electrical charge are called insulators. Amber, latex balloons, dry air, and silk are insulators. Materials that can quickly carry off a buildup of electrical charge are called conductors. Metals are generally good conductors, because electrons in metals are loosely bound to their atoms and can transmit charge through the material. Other conductors include salt solutions and graphite. There is no sharp line between insulators and conductors. Dry wood, paper, and water are poor electrical conductors, but not completely insulating. A relatively poor conductor such as silicon may be called a semiconductor. When an insulator is charged, the charge may remain in one spot. When a conductor is charged, the charge spreads out over the whole surface. A capacitor (sometimes called a condenser) is a device to store energy. Fundamentally, it consists of two parallel metal plates with air or an insulating material in between. The insulating material is called a dielectric. The capacitor is charged by connecting it to a battery or power supply. This causes a negative charge (excess electrons) to build up on one plate, and a corresponding positive charge (a dearth of electrons) on the other plate. Between the two plates we find an electric field, and a force pulling the plates toward each other. The charge builds up until the capacitor reaches a saturation point, which depends on the size of the plates and their separation. (Increasing the plate size or decreasing their separation increases the charge and electric field that can be built up.) The capacitor can release stored charge back into an electric circuit. A current quickly flows from the capacitor until the charge is drained. https://uciunex.instructure.com/courses/9455/pages/electrostatics?module_item_id=479321

SMR 2.6.f: Demonstrate knowledge of the definitions of power, voltage differences, current, and resistance and calculate their values in simple circuits.

Power is the force motivating electrons to flow, called voltage. It is the measurement of potential energy that is relative between two points. Voltage is measured in volts. To solve for the voltage (E), you multiply current (I) times resistance (R). E = I * R Current is the continuous movement of electrons in a circuit. Resistance is the opposition to motion. Resistors are important otherwise too many electrons will move through the circuit. R_total = R1 + R2 + R3 + ...Rn --> IN SERIES R_total = 1 / (1 / R1) + (1 / R2) + ... (1 / Rn) --> IN PARALLEL To find the total current: I = E / R Thus, the total current (I) is found by taking the voltage of the power source and dividing it by the total resistance. http://sciencecsetprep.weebly.com/electricity-and-magnetism.html

SMR 4.1.c: Demonstrate knowledge of the factors that contribute to a star's color, size, and luminosity and how a star's light spectrum and brightness can be used to identify compositional elements, movements, and distance from Earth.

Analyzing the spectrum of a star can teach us all kinds of things in addition to its temperature. We can measure its detailed chemical composition as well as the pressure in its atmosphere. From the pressure, we get clues about its size. We can also measure its motion toward or away from us and estimate its rotation. Stars come in a wide variety of sizes. At some periods in their lives, stars can expand to enormous dimensions. Stars of such exaggerated size are called giants. Luckily for the astronomer, stellar spectra can be used to distinguish giants from run-of-the-mill stars (such as our Sun). Suppose you want to determine whether a star is a giant. A giant star has a large, extended photosphere. Because it is so large, a giant star's atoms are spread over a great volume, which means that the density of particles in the star's photosphere is low. As a result, the pressure in a giant star's photosphere is also low. This low pressure affects the spectrum in two ways. First, a star with a lower-pressure photosphere shows narrower spectral lines than a star of the same temperature with a higher-pressure photosphere. The difference is large enough that careful study of spectra can tell which of two stars at the same temperature has a higher pressure (and is thus more compressed) and which has a lower pressure (and thus must be extended). This effect is due to collisions between particles in the star's photosphere--more collisions lead to broader spectral lines. Collisions will, of course, be more frequent in a higher-density environment. Think about it like traffic--collisions are much more likely during rush hour, when the density of cars is high. Absorption lines of a majority of the known chemical elements have now been identified in the spectra of the Sun and stars. If we see lines of iron in a star's spectrum, for example, then we know immediately that the star must contain iron. When we measure the spectrum of a star, we determine the wavelength of each of its lines. If the star is not moving with respect to the Sun, then the wavelength corresponding to each element will be the same as those we measure in a laboratory here on Earth. But if stars are moving toward or away from us, we must consider the Doppler effect (see The Doppler Effect). We should see all the spectral lines of moving stars shifted toward the red end of the spectrum if the star is moving away from us, or toward the blue (violet) end if it is moving toward us (Figure 2). The greater the shift, the faster the star is moving. Such motion, along the line of sight between the star and the observer, is called radial velocity and is usually measured in kilometers per second. William Huggins, pioneering yet again, in 1868 made the first radial velocity determination of a star. He observed the Doppler shift in one of the hydrogen lines in the spectrum of Sirius and found that this star is moving toward the solar system. Today, radial velocity can be measured for any star bright enough for its spectrum to be observed. As we will see in The Stars: A Celestial Census, radial velocity measurements of double stars are crucial in deriving stellar masses. https://courses.lumenlearning.com/astronomy/chapter/using-spectra-to-measure-stellar-radius-composition-and-motion/ Stars come in different colors. You can see different colored stars when you look at the night sky. Sirius, the brightest star in the night sky--it's also the eye of the hunting dog following Orion--is white or blue-white. Betelgeuse, in Orion's right shoulder, is red. Aldebaran, near the base of the horns of Taurus, is orange. A famous double star in the constellation Cygnus is made up of one very yellow star, Albireo, next to a fainter green one. A star's color comes from its surface temperature. The surfaces of stars are generally thousands of degrees Kelvin. The interiors are much hotter--millions of degrees. Different surface temperatures result in different colors: 1. The hottest stars, with surface temperatures of tens of thousands of degrees (up to 50,000 K), are blueish. 2. The Sun's surface temperature is about 6,000 K, which makes it appear yellow. 3. The red star Betelgeuse, with a surface temperature of about 3,500 K, is much cooler. An object such as a star radiates across the electromagnetic spectrum, that is, at all wavelengths. However, the emission has a peak at a particular wavelength, depending on the temperature. The size of a star is given in terms of its radius. The radius of the Sun (often written Rsun) is about 7 x 10^8 m. As stars go, the Sun is of about average size. Using Rsun as the standard of measurement: - Sizes of "normal" or "dwarf" stars range from about 0.1 Rsun (about the size of Jupiter) to about 5 Rsun. - A red giant star--such as Aldebaran, in the constellation Taurus--which represents a particular phase in the life of a normal star, may be 70 Rsun. - And a supergiant (like Betelgeuse--a very massive star on its way to becoming a supernova) might be close to 100 Rsun in size. To understand the size of giant and supergiant stars, it helps to compare their sizes to the solar system: When the Sun becomes a red giant toward the end of its lifetime, its surface will extend to about the orbit of Mercury. A supergiant in its place would engulf Mars. A star's luminosity is the energy it radiates per unit time, in units of Watts. Luminosity should not be confused with a star's apparent magnitude, or how bright it appears from Earth. The apparent magnitude depends on the star's luminosity and its distance. Luminosity is a function of the star itself and does not depend on distance. Stars vary greatly in luminosity. The Sun, of course, seems very bright, but that is only because it is very near. It is actually rather average in luminosity. A red supergiant like Betelgeuse may be 15,000 times more luminous, and a blue supergiant like Rigel (also in Orion) about 50,000 times more luminous! Without knowing its distance, there is no way to tell how luminous a given star is. Very luminous stars may appear dim at a great distance. Ordinary stars that are nearby may seem more luminous than they really are. The Greek astronomers around 150 BCE began rating stars according to their apparent brightness. A bright star was said to be of the first magnitude, while lesser ones were the second magnitude, and so on. Sixth magnitude stars are at the limit of what can be seen with the unaided eye. The magnitude system is still used, although the limits have been defined mathematically.

SMR 2.4.f: Demonstrate knowledge of how lenses are used in simple optical systems, including the camera, telescope, microscope, and eye.

Light rays are refracted when it passes through curved surfaces, lens (laws of refraction of light). The bending of the light is a result of light being slowed down as it passes from one medium (air) through another medium (the lens). There are two types of lens: concave and convex. The concave lens has at least one surface curving inwards and acts as a diverging lens. Images formed by concave lenses are. The convex lens has at least one lens that curves outward. Simple optical systems use one or more lenses to focus light and produce an image. Camera- the camera uses several kinds of lenses, which can be moved to focus on images at different distances, and mirrors to capture an image. Telescope- A refracting telescope lens works to refract (bend) light that enters the eyepiece. Because the bent light moves through the telescope and crosses at a point, the image is upside down (there are lenses, however, such as the Barstow lens, that may flip it right side up). In a reflecting telescope, it uses curved mirrors to bounce the light instead of using lenses (this method prevents light from being bent, which causes colors to change and light to be unfocused). Microscope- A simple microscope consists of one lens, while a compound microscope uses more than one lens. As light bounces on a mirror on the bottom of the microscope, the light passes around the object on the microscope slide. The light passes through the microscope tube and passes the lens, which slows down and bends (refracts). Eye- one of the features of the eye is the cornea, which works just like any other lens. The cornea focuses the light rays and bends (refracts) them onto the lens (biconvex, also known as double convex) so that they come to a point on the retina. The upside-down image is formed on the retina and is corrected by the brain. If an object is near, the lens changes its shape to short and fat, and if an object is far away, the lens becomes flat and thin. https://uciunex.instructure.com/courses/9455/pages/lenses?module_item_id=479241 --> diagrams!!!

SMR 2.1.e: Demonstrate knowledge of the characteristics of the different states of matter.

Matter of any kind can most often be described as being a solid, liquid, or gas. These three forms of matter are referred to as the most common states of matter, even though there is another state of matter known as plasma. Therefore, there are four states of matter. Each of the three common states contains varying observable physical properties. A solid has a definite shape and a definite volume. A liquid has a distinct volume, yet it does not have definite shape. Rather, a liquid retains the shape of its container. A gas (also known as vapor) has no distinct volume or shape, rather, it conforms to the volume and shape of its container. Plasma, the fourth state of matter, is an extremely hot gas-like state, composed of free ions and electrons that can carry an electrical current. States are made of plasma. Examples of plasma on Earth are neon lights, lightning, and fire (and, or course, plasma TV!). Interesting fact! Although plasma is the least familiar state of matter on Earth, it is actually the most common form of matter--in fact, plasma makes up 99% of all visible matter in the Universe. All atoms and molecules are in perpetual motion. In any given substance or element, the relative level of motion of its atoms or molecules increases from solids to liquids to gases. As discussed in the lesson on thermodynamics, when a thermometer is placed into a substance and the temperature is measured, the average kinetic energy of motion of the atoms is being measured. The various states of matter of a given substance depend on the balance between the various forces found within and outside the substance. These forces or bonds can be broken or reformed depending upon the energy input. For example, heat energy can be used to break the bonds found within a solid substance by increasing the molecular motion of the atoms within a specific substance. This can result in the solid substance changing its state into a liquid or even into a gaseous state. As more heat is added, the motion of particles becomes faster. This leads to change in state from solid to liquid to gaseous. The Law of Conservation of Mass states that matter can neither be created nor destroyed. However, if energy is present, matter can be transformed from one state to another (i.e., when sufficient thermal energy is applied to liquid water, it can be transformed into the gaseous state). https://uciunex.instructure.com/courses/9475/pages/refresher-states-of-matter?module_item_id=480761

SMR 2.3.a: Apply knowledge of Newton's laws of motion and law of universal gravitation and recognize the relationship between these laws and the laws of conservation of energy and momentum.

Newton's First Law states that "an object moves at constant velocity if there is no net force acting upon it." In other words, an object will move with constant velocity as long as there is no friction/air resistance or a force that acts to slow it down. For example, a spaceship traveling in space does not need any fuel to keep moving as there is no friction (such as air) to slow it down. Friction is the force that acts to oppose the motion of two touching surfaces over each other. It is caused by the intermolecular force of attraction between the molecules of the surfaces. There are two kinds of frictional force static and kinetic. Static friction is the force between two touching surfaces when a force is applied to one of them but they are not moving. Kinetic (aka sliding) friction is the force where one surface is moving over the other one at a constant speed. Newton's Second Law states that if the mass of an object is constant, then the force is proportional to the acceleration of the object. Force = mass * acceleration (F = ma). If the momentum of an object changes, for example, if it accelerates, then there must be a resultant force acting on it. Force = change in momentum / time. Momentum = mass * velocity. The amount of acceleration depends on the object's mass and also the strength of the net force. Newton's Second Law tells us what is happening to an object when a net force is present. This law also helps to explain why you can throw a golf ball further than a shot-put. Because the mass of the shot-put is greater than that of the golf ball, that the same force your arm provides to the shot-put results in smaller acceleration. Compared to the golf ball, the shot-put, with its smaller acceleration, will have less speed and thus will travel a shorter distance. An object has an acceleration if its velocity changes in any way, whether in speed, direction, or both. For example, if an object is slowing down, it is accelerating. For example, a baseball thrown by a pitcher accelerates as the pitcher applies a force by moving his arm. Newton's Third Law states, "for any force, there is always an equal and opposite reaction force." According to the second law, if a person standing on earth has a downward force, then they would continue accelerating downward. But, we know that they don't. That is because as you exert a downward force on the Earth is offset by an equal and opposite force that pushes upward on you by Earth, For example, a rocket blasting into outer space is propelled by a force equal and opposite to the force with which gas is expelled out its back. Newton's Law of Universal Gravitation is "F = G* Mm / d2." This law states that there is a gravitational force of attraction between any two objects that have a mass and this force depends on the mass of each object and the distance between them. For example, the gravitational force between Saturn and one of its moons, Tethys, can be calculated from their masses and the distance between them. http://sciencecsetprep.weebly.com/forces-and-motions.html

SMR 2.3.b: Demonstrate knowledge of the definition of pressure and how pressure relates to fluid flow and buoyancy, including describing everyday phenomena (e.g., the functioning of heart valves, atmospheric pressure).

Pressure is the force, which acts at right angles, that is exerted by solids, liquids, or gases on a unit area of a substance (solid, liquid, or gas). Pressure is found by force / area. Within a vessel of water that has three holes, one on the top, one in the middle, and one on the bottom, the force of the fluid water flowing out of the holes with differ. The water flowing out of the bottom hole has greater pressure and shoots out further than the water flowing out of the top-most hole. There are fewer water molecules pressing down on the water near the top hole so there is less force, and thus, less pressure, whereas the opposite is true for the bottom-most hole. Pascal's law of fluid pressures states that pressure applied anywhere to a body of fluid will cause the force to be transmitted equally in all directions. The force acts at right angles to any surface in contact with the fluid. Buoyancy is the upward force an object feels when it is fully or partially submerged in water. Objects placed into water undergo two forces: the upward force (buoyant) and the downward pull of gravity. Objects that float are called positively buoyant. Objects that sink are negatively buoyant. Objects that neither sink nor gloat are neutrally buoyant. So, to determine if an object will sink or float, we need to know the density of the object. If the density of a solid object is greater than the density of the liquid, then it will sink. If the density of a solid object is less than the density of the liquid, then it will float. According to Archimedes Principle, "any object, wholly or partly immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object." So, when an object floats, not just its weight is considered, but the amount of water that is displaced. That is why a very large ship can float on water, whereas a penny sinks. Heart valves are inserted into your heart to release the pressure. http://sciencecsetprep.weebly.com/forces-and-motions.html

SMR 4.1.b: Demonstrate knowledge of how astronomical instruments are used to collect data and how astronomical units are used to describe distances.

Telescopes: Telescopes allow scientists to analyze the light the telescopes collect. Using this data, scientists can help reveal the chemical composition, temperature, or even the speed of an object light years away. In order to study other aspects of space, scientists use other telescope instruments to capture images of different wavelengths. And, if you've wondered why scientists haven't invented one telescope that could capture all of the different wavelengths, it is due to the fact that the type of wavelength we are studying dictates the build of the telescope. To have one that will capture all is just not possible, unfortunately. The astronomical unit is a convenient measure of the scale of the solar system. One astronomical unit (AU) is the average distance from the Sun to Earth. An AU is equivalent to 93 million miles, or 1.5 x 10^8 km. Solar system distance benchmarks to remember: - Jupiter orbits at about 5 AU. - Pluto is found at a distance of 30-50 AU. The light-year (ly) is a convenient unit for distances on an interstellar scale. A light-year is the distance traveled by a photon of light in one year, which is 9.5 trillion km (or 9.5 x 10^12 km). Note that the light-year is not, as it might seem, a unit of time; it is a unit of distance. Astronomers often use the parsec for astronomical distance measurements (1 parsec equals 3.26 ly).

SMR 3.2.a: Demonstrate knowledge of the importance of mitosis and meiosis as processes of cellular and organismal reproduction.

Mitosis: The process of cell division when a plant or animal cell divides for growth or repair. Mitosis ensures that the two new nuclei (daughter cells) have the same number of chromosomes, called the diploid number. Mitosis always has four stages and before mitosis begins, there is always interphase. Interphase: This is an active period during cell division. The cell is preparing materials to produce "copies" of all of its components. Chromatin threads in the nucleus duplicate. This is also taking place while the cell is growing and carrying out processes needed for life. Stage 1 - PROPHASE: The nuclear membrane disappear and chromatin thread coils up to form chromosomes. Each chromatin thread is joined by a centromere. The centrioles move to the opposite poles of the cell. Stage 2 - METAPHASE: The centrioles project protein fibers called spindle fibers which join together to form a sphere. Chromosomes move toward the equator and there the centromeres become attached to spindle fibers. Stage 3 - ANAPHASE: The centromere duplicates and the two daughter chromosomes move to the opposite poles of the spindle. Stage 4 - TELOPHASE: Spindle fibers and astral rays disappear and the nuclear membranes form around the daughter chromosomes. The centrioles also duplicate. Cytokinesis takes place (this is the division of the cytoplasm). Each daughter cell now enters interphase. Meiosis: the process of cell division where a cell divides to produce sex cells. Meiosis is split into two divisions: the first meiotic division (reduction division) and the second meiotic division. Meiosis ensures that each daughter cell has half the number of chromosomes, known as the haploid number (sex cells have half of your DNA to combine with the sex cells of another individual). PROPHASE 1: Chromosomes become visible, chromosomes split into chromatids, chromatids exchange segments (crossover), nucleus disappears, spindle forms, and nuclear envelope forms. METAPHASE 1: Spindle fibers from one pole of the cell attach to one chromosome from each pair and the spindle fibers from the opposite pole attach to the homologous chromosomes. ANAPHASE 1: Begins when two chromosomes of each bivalent separate and start moving toward opposite poles of the cell as a result of the action of the spindle. There are 23 divided chromosomes on each side. TELOPHASE 1: Homologous chromosome pairs reach the poles of the cell, the nuclear envelope forms around them, and cytokinesis follows to produce two daughter cells. Meiosis 1 is complete. PROPHASE 2: Nuclear envelope breaks down and spindle apparatus forms, chromosomes become visible (no new chromosome replication occurs before meiosis 2), centrioles duplicate. METAPHASE 2: Single chromosomes align on the metaphase plate and the kinetochores of the sister chromatids face opposite poles and are attached to the kinetochore-microtubule coming from that pole. ANAPHASE 2: Centromeres separate and the two chromatids of each chromosome move to opposite poles on the spindle. CYTOKINESIS: Cell divides again. TELOPHASE 2: Nuclear envelope forms around each set of chromosomes. The cells are now completely divided (four daughter cells each with a haploid set of chromosomes). For males, it's four sperm cells and in females, it is one ova cell (the other three ova are reabsorbed into the parent's body). In plants, it is four spores. Chromosomes are the cell's way of neatly arranging long strands of DNA. Non-sex cells have two sets of chromosomes, one set from each parent. Meiosis makes sex cells with only one set of chromosomes. For example, human cells have 46 chromosomes, with the exception of sperm and eggs, which contain only 23 chromosomes each. When a sperm cell fertilizes an egg, the 23 chromosomes from each sex cell combine to make a zygote, a new cell with 46 chromosomes. The zygote is the first cell in a new individual. One of the benefits of sexual reproduction is the diversity it produces within a population. That variety is a direct product of meiosis. Every sex cell made from meiosis has a unique combination of chromosomes. This means that no two sperm or egg cells are genetically identical. Every fertilization event produces new combinations of traits. This is why siblings share DNA with parents and each other but are not identical to one another. Mitosis is important for sexual reproduction indirectly. It allows the sexually reproducing organism to grow and develop from a single cell into a sexually mature individual. This allows organisms to continue to reproduce through the generations.

SMR 2.4.g: Compare and contrast the transmission, reflection, and absorption of light in matter.

Atoms and molecules contain electrons. It is often useful to think of these electrons as being attached to the atoms by springs. The electrons and their attached springs have a tendency to vibrate at specific frequencies. Similar to a tuning fork or even a musical instrument, the electrons of atoms have a natural frequency at which they tend to vibrate. When a light wave with that same natural frequency impinges upon an atom, then the electrons of that atom will be set into vibrational motion. If a light wave of a given frequency strikes a material with electrons having the same vibrational frequencies, then those electrons will absorb the energy of the light wave and transform it into vibrational motion. During its vibration, the electrons interact with neighboring atoms in such a manner as to convert its vibrational energy into thermal energy. Subsequently, the light wave with that given frequency is absorbed by the object, never again to be released in the form of light. So the selective absorption of light by a particular material occurs because the selected frequency of the light wave matches the frequency at which electrons in the atoms of that material vibrate. Since different atoms and molecules have different natural frequencies of vibration, they will selectively absorb different frequencies of visible light. Reflection and transmission of light waves occur because the frequencies of the light waves do not match the natural frequencies of vibration of the objects. When light waves of these frequencies strike an object, the electrons in the atoms of the object begin vibrating. But instead of vibrating in resonance at a large amplitude, the electrons vibrate for brief periods of time with small amplitudes of vibration; then the energy is reemitted as a light wave. If the object is transparent, then the vibrations of the electrons are passed on to neighboring atoms through the bulk of the material and reemitted on the opposite side of the object. Such frequencies of light waves are said to be transmitted. If the object is opaque, then the vibrations of the electrons are not passed from atom to atom through the bulk of the material. Rather the electrons of atoms on the material's surface vibrate for short periods of time and then reemit the energy as a reflected light wave. Such frequencies of light are said to be reflected. https://www.physicsclassroom.com/class/light/Lesson-2/Light-Absorption,-Reflection,-and-Transmission

SMR 3.5.d: Demonstrate knowledge of technologies that allow humans to influence the genetic traits of organisms.

Biotechnology is a field of life science that uses living organisms and biological systems to create modified or new organisms or useful products. A major component of biotechnology is genetic engineering. The popular concept of biotechnology is one of the experiments happening in laboratories and cutting-edge industrial advances, but biotechnology is much more integrated into most people's everyday lives than it seems. The vaccines you get, the soy sauce, cheese, and bread you buy at the grocery store, the plastics in your daily environment, your wrinkle-resistant cotton clothing, the cleanup after news of oil spills, and more are all examples of biotechnology. They all "employ" living microbes to create a product. Even a Lyme disease blood test, a breast cancer chemotherapy treatment, or an insulin injection might be the result of biotechnology. Early examples of this are selective breeding of plants and animals thousands of years ago. Today, scientists edit or transfer DNA from one species to another. Biotechnology harnesses these processes for a wide variety of industries, including medicine, food and agriculture, manufacturing, and biofuels. Biotechnology would not be possible without genetic engineering. In modern terms, this process manipulates cells' genetic information using laboratory techniques in order to change the traits of living organisms. Scientists may use genetic engineering in order to change the way an organism looks, behaves, functions, or interacts with specific materials or stimuli in its environment. Genetic engineering is possible in all living cells; this includes micro-organisms such as bacteria and individual cells of multicellular organisms, such as plants and animals. Even the human genome can be edited using these techniques. Sometimes, scientists alter genetic information in a cell by directly altering its genes. In other cases, pieces of DNA from one organism are implanted into the cells of another organism. The new hybrid cells are called transgenic. Genetic engineering may seem like an ultra-modern technological advance, but it has been in use for decades, in numerous fields. In fact, modern genetic engineering has its roots in ancient human practices that were first defined by Charles Darwin as artificial selection. Artificial selection, which is also called selective breeding, is a method for deliberately choosing mating pairs for plants, animals, or other organisms based on desired traits. The reason to do this is to create offspring with those traits and to repeat the process with future generations to gradually strengthen the traits in the population. Although artificial selection does not require microscopy or other advanced lab equipment, it is an effective form of genetic engineering. Although it began as an ancient technique, humans still use it today. Common examples include: - Breeding livestock. - Creating flower varieties. - Breeding animals, such as rodents or primates, with specific desired traits for susceptibility for diseases for research studies. https://sciencing.com/biotechnology-genetic-engineering-an-overview-13718445.html

SMR 2.6.c: Relate electric currents to magnetic fields and describe the application of these relationships, such as in electromagnets, electric current generators, motors, and transformers.

Electric current is the rate of flow of electric charge (measured by electrons). In a magnetic force, the force between two moving charges can be electric currents. Electromagnetics have several applications, all of which attract metals when they are switched on. They convert electric energy to mechanical energy. On the other hand, electric current generators produce electric current from mechanical energy. Electric motors use the Lorentz force (a current-carrying wire that goes through a magnetic field which can produce movement) to transform electrical energy into mechanical energy. A transformer consists of two coils of wire that are wound onto the same core of soft ferromagnet material, which is unable to retain its magnetism. A transformer is used to change an alternating electromotive force in one of the coils to a different electromotive force in the other coil. It can change the values of voltage and current without changing the frequency. It consists of a primary and secondary coil. The first coil in a transformer is connected to the AC voltage and is called the primary coil. The second coil is the one in which the AC voltage is induced and it is called the secondary coil. Step-up transformer has a secondary coil that is greater, has more turns, than that in the primary coil. This increases voltage. Step-down transformer has a secondary coil that is less, has fewer turns, than that in the primary coil. This reduces voltage. Turns ratio is the ratio of the number of turns in the secondary coil to the number of turns in the primary coil. The relationship between the voltage and number of turns in each coil is: voltage in secondary coil / voltage in primary coil = number of turns on secondary coil / number of turns on primary coil V_s / V_p = N_s / N_p http://sciencecsetprep.weebly.com/electricity-and-magnetism.html

SMR 2.4.d: Apply knowledge of electromagnetic radiation, including analyzing evidence that supports the wave and particle models that explain the properties of electromagnetic radiation.

Electromagnetic radiation is one of the many ways that energy travels through space. The heat from a burning fire, the light from the sun, the X-rays used by your doctor, as well as the energy used to cook food in a microwave are all forms of electromagnetic radiation. While it's good to have a basic understanding of what electromagnetic radiation is, most chemists are less interested in the physics behind this type of energy, and are far more interested in how these waves interact with matter. More specifically, chemists study how different forms of electromagnetic radiation interact with atoms and molecules. This relationship is given by the following equation: c = lv where l (the Greek lambda) is the wavelength (in meters, m) and v (the Greek nu) is the frequency (in Hertz, Hz). Their product is the constant c, the speed of light, which is equal to 3.00 x 10^8 m/s. This relationship reflects an important fact: all electromagnetic radiation, regardless of wavelength or frequency, travels at the speed of light. The visible spectrum—that is, light that we can see with our eyes—makes up only a small fraction of the different types of radiation that exist. To the right of the visible spectrum, we find the types of energy that are lower in frequency (and thus longer in wavelength) than visible light. These types of energy include infrared (IR) rays (heat waves given off by thermal bodies), microwaves, and radio waves. These types of radiation surround us constantly, and are not harmful, because their frequencies are so low. To the left of the visible spectrum, we have ultraviolet (UV) rays, X-rays, and gamma rays. These types of radiation are harmful to living organisms, due to their extremely high frequencies (and thus, high energies). Planck found that the electromagnetic radiation emitted by blackbodies could not be explained by classical physics, which postulated that matter could absorb or emit any quantity of electromagnetic radiation. Planck's discovery that electromagnetic radiation is quantized forever changed the idea that light behaves purely as a wave. Electromagnetic radiation can be described by its amplitude (brightness), wavelength, frequency, and period. https://www.khanacademy.org/science/ap-chemistry/electronic-structure-of-atoms-ap/bohr-model-hydrogen-ap/a/light-and-the-electromagnetic-spectrum

SMR 2.1.g: Demonstrate knowledge of the physical and chemical characteristics, including pH, of acids, bases, and neutral solutions.

In chemistry, solutions can be subdivided as being acidic, basic, or neutral. Each type of solution has a specific physical and chemical property, which is unique to that solution. Acidic, basic, and neutral solutions are among the most common compounds encountered both in nature and in the chemistry lab. Many are used in industry and in the household, and some are important components of biological fluids. For instance, hydrochloric acid is an acidic solution used in industry and is also found in our stomach as the main constituent of gastric juice to digest the food we eat. An acidic solution is defined as a substance whose molecules release hydrogen ions (H+) when dissolved in water. A hydrogen atom only consists of a proton and an electron; hydrogen ions (H+) are simply protons with no electrons. Acids are often called proton donors for this reason. Common examples of acids include hydrochloric acid HCl and sulfuric acid H2SO4. When acidic solutions are mixed with basic ones, a neutralization reaction occurs. The products of a neutralization reaction do not have any characteristic properties of either the acidic or basic solutions. For example, when hydrochloric acid is mixed with a solution of hydroxide, the reactants form water and sodium chloride (salt) as the products. In general, a neutralization reaction results in the production of water and salt due to the reaction of an acidic solution and a basic solution. Scientists can measure the strength of an acid or a base through the use of the pH scale on a scale of 0-14, when 0 is extremely acidic and 14 is extremely basic. A pH of 7 is considered as neutral for water. Specifically, the pH scale measures the concentration of H+ (aq) in an aqueous solution. As we make the solution more acidic, the concentration of H+ ions increases, and the pH decreases. In a basic solution, the concentration of OH- ions is measured through the use of an instrument called a pH meter. Gastric juice (also known as hydrochloric acid or HCl), found within the stomach, has a pH of 2.00, extremely acidic. Household ammonia (NH3) has a pH of 12.00, extremely basic. Water, H2O has a pH of 7.00, neutral. Human blood has a pH range of about 7.35 to 7.45, slightly basic. In biological systems, many reactions involve proton transfers whose reaction rates depend upon the balance of H+ ions. Due to the fast rates of biological reactions, the pH of biological fluids must be maintained within narrow margins. Disease, illness, and even death can result if the pH of blood varies much from the narrow range of 7.35-7.45. https://uciunex.instructure.com/courses/9475/pages/refresher-acids-and-bases?module_item_id=480786

SMR 2.1.h: Apply knowledge of the physical and chemical properties of water.

Water molecules are polar, so they form hydrogen bonds. This givens water unique properties, such as a relatively high boiling point, high specific heat, cohesion, adhesion, and density. You are probably already familiar with many of water's properties. For example, you no doubt know that water is tasteless, odorless, and transparent. In small quantities, it is also colorless. However, when a large amount of water is observed, as in a lake or the ocean, it is actually light blue in color. The blue hue of water is an intrinsic property and is caused by selective absorption and scattering of white light. Sunlight is needed by water plants and other water organisms for photosynthesis. Each molecule of water consists of one atom of oxygen and two atoms of hydrogen, so it has the chemical formula H2O. The arrangement of atoms in a water molecule explains many of water's chemical properties. In each water molecule, the nucleus of the oxygen atom (with 8 positively charged protons) attracts electrons much more strongly than do the hydrogen nuclei (with only one positively charged proton). This results in a negative electrical charge near the oxygen atom (due to the "pull" of the negatively charged electrons toward the oxygen nucleus) and a positive electrical charge near the hydrogen atoms. A difference in electrical charge between different parts of a molecule is called polarity. A polar molecule is a molecule in which part of the molecule is positively charged and part of the molecule is negatively charged. Opposite electrical charges attract one another. Therefore, the positive part of one water molecule is attracted to the negative parts of other water molecules. Because of this attraction, bonds form between hydrogen and oxygen atoms of adjacent water molecules. This type of bond always involves a hydrogen atom, so it is called a hydrogen bond. Hydrogen bonds also hold together the two nucleotide chains of a DNA molecule. Water has some unusual properties due to its hydrogen bonds. One property is cohesion, the tendency for water molecules to stick together. The cohesive forces between water molecules are responsible for the phenomenon known as surface tension. The tendency of water to stick together is illustrated by dew drops. Another important physical property of water is adhesion. In terms of water, adhesion is the process of bonding of a water molecule to another substance, such as the sides of a leaf's veins. This process happens because hydrogen bonds are special in that they break and reform with great frequency. This constant rearranging of hydrogen bonds allows a percentage of all molecules in a given sample to bond to another substance. This grip-like characteristic that water molecules form causes capillary action, the ability of a liquid to flow against gravity in a narrow space. Adhesion and capillary action are necessary to the survival of most organisms. It is the mechanism that is responsible for water transport in plants from roots to stems, and in animals through small blood vessels. Hydrogen bonds also explain why water's boiling point (100 degrees C) is higher than the boiling points of similar substances without hydrogen bonds. Because of water's relatively high boiling point, most water exists in a liquid state on Earth. Furthermore, water has a high specific heat because it takes a lot of energy to raise or lower the temperature of water. As a result, water plays a very important role in temperature regulation. Since cells are made up of water, this property helps to maintain homeostasis. The melting point of water is 0 degrees C. Below this temperature, water is a solid (ice). Unlike most chemical substances, water in a solid state has a lower density than water in a liquid state. This is because water expands when it freezes. Again, hydrogen bonding is the reason. Water is most dense at about 4 degrees C. As a result, the water at the bottom of a lake or the ocean usually has a temperature of about 4 degrees C. In climates with cold winters, this layer of 4 degrees C water insulates the bottom of a lake from freezing temperatures. Lake organisms such as fish can survive the winter by staying in this cold, but unfrozen, water at the bottom of the lake. https://www.ck12.org/biology/structure-and-properties-of-water/lesson/biochemical-properties-of-water-advanced-bio-adv/#:~:text=Summary,%2C%20cohesion%2C%20adhesion%20and%20density.

SMR 3.4.f: Compare and contrast sexual and asexual reproduction.

- Asexual reproduction involves one parent and produces offspring that are genetically identical to each other and to the parent. - Sexual reproduction involves two parents and produces offspring that are genetically unique. - During sexual reproduction, two haploid gametes join in the process of fertilization to produce a diploid zygote. - Meiosis is the type of cell division that produces gametes. Sexual reproduction just means combining genetic material from two parents. Asexual reproduction produces offspring genetically identical to the one parent. Cell division is how organisms grow and repair themselves. It is also how many organisms produce offspring. For many single-celled organisms, reproduction is a similar process. The parent cell simply divides to form two daughter cells that are identical to the parent. In many other organisms, two parents are involved, and the offspring are not identical to the parents. In fact, each offspring is unique. Reproduction is the process by which organisms give rise to offspring. It is one of the defining characteristics of living things. There are two basic types of reproduction: asexual reproduction and sexual reproduction. Asexual reproduction involves a single parent. It results in offspring that are genetically identical to each other and to the parent. All prokaryotes and some eukaryotes reproduce this way. There are several different methods of asexual reproduction. They include binary fission, fragmentation, and budding. - Binary fission occurs when a parent cell splits into two identical daughter cells of the same size. - Fragmentation occurs when a parent organism breaks into fragments, or pieces, and each fragment develops into a new organism. Starfish reproduce this way. A new starfish can develop from a single ray, or arm. Starfish, however, are also capable of sexual reproduction. - Budding occurs when a parent cell forms a bubble-like bud. The bud stays attached to the parent cell while it grows and develops. When the bud is fully developed, it breaks away from the parent cell and forms a new organism. Asexual reproduction can be very rapid. This is an advantage for many organisms. It allows them to crowd out other organisms that reproduce more slowly. Bacteria, for example, may divide several times per hour. Under ideal conditions, 100 bacteria can divide to produce millions of bacterial cells in just a few hours! However, most bacteria do not live under ideal conditions. If they did, the entire surface of the planet would soon be covered with them. Instead, their reproduction is kept in check by limited resources, predators, and their own wastes. This is true of most other organisms as well. Sexual reproduction involves two parents. In sexual reproduction, parents produce reproductive cells--called gametes--that unite to form an offspring. Gametes are haploid cells. This means they contain only half the number of chromosomes found in other cells of the organism. Gametes are produced by a type of cell division called meiosis, which is described in detail in a subsequent concept. The process in which two gametes unite is called fertilization. The fertilized cell that results is referred to as a zygote. A zygote is diploid cell, which means that it has twice the number of chromosomes as a gamete.

SMR 2.2.e: Demonstrate knowledge of the central role of carbon in the chemistry of living systems.

All living things are made of carbon, along with other elements such as nitrogen, hydrogen, and many others. Carbon is a very special element. Due to the number of electrons in its outmost shell, carbon can combine with a large number of other elements to form a variety of useful compounds. Carbon has bonding characteristics, which allow the formation of numerous organic molecules of different sizes, shapes, and chemical properties. This allows carbon to be the foundational and fundamental element and the biochemical basis of life. All atoms can contain a maximum of eight electrons (octet) in the valance (outermost) shell, except hydrogen and helium. If an atom has less than four electrons in the outermost shell, it prefers to donate or give away those electrons to other atoms. On the other hand, if an atom has more than four electrons, it takes the electrons from other atoms to complete the octet in its outermost shell. Carbon is a very special element because it has exactly four electrons in the outermost shell and four vacant orbitals. This gives carbon enormous flexibility in bonding patterns. Carbon shares its electrons instead of giving or taking the electrons from other atoms to make a covalent bond. Therefore carbon can form four bonds with other atoms or to itself in a repeating sequence. This gives the complexity and large size of the molecules that are formed by carbon, including the molecules in the living system. Carbon forms strong bonds with many elements, and therefore carbon compounds are often relatively stable and unreactive. All body polymers — such as proteins, nucleic acids (DNA, RNA), fatty acids, carbohydrates, etc. — are made of carbon. Since four different atoms or compounds can be attached to one carbon atom, carbon compounds are mostly chiral ( non-super-imposable mirror images). Chirality plays an important role in biological systems for the specificity of the reaction — e.g., enzymes are able to recognize only one isomer but not the mirror image. Therefore, carbon is central to living systems.

SMR 2.1.b: Differentiate between atoms and their isotopes, ions, molecules, elements, and compounds.

An atom is the smallest particle that represents an element. In other words it is the smallest part of a substance that exists and retains the properties of that substance. Isotopes are atoms with differing numbers of neutrons that affect the mass number (which is made up of protons and neutrons). Thus, different isotopes of a given element will have different mass numbers. However, differing isotopes with different numbers of neutrons will still have the same chemical properties. To find the number of protons, neutrons, and electrons in an isotope: 1. Find the atomic number of the element and the mass number (sum of protons and neutrons) of the isotope. The mass number is usually written right after the name of the element. 2. To find the number of protons: the atomic number is the number of protons in an element. 3. To find the number of electrons: if the atom has a neutral charge, then you must have an equal number of protons and electrons. If the atom has a negative charge, then you will have more electrons that protons. An atom with a positive charge will have fewer electrons than protons. Protons - total charge = electrons. 4. To find the number of neutrons: take the mass number and subtract the number of protons to find the neutrons. Most naturally occurring atomic nuclei are stable and remain intact indefinitely. Others are not stable and spontaneously emit rays, radiation, and particles (i.e., alpha, gamma). As radiation of particles are emitted, unstable radioactive elements will transform into stable ones. Ions are atoms that have a net gain or net loss of electrons, which results in the formation of negatively or positively charged atoms. Normally, atoms do not contain a net electrical charge--they are neutral. The number of protons found within an atom usually equals the number of electrons found outside the nucleus in a neutral atom. However, in nature, atoms can readily gain or lose electrons. If electrons are lost of gained, an ion is formed. Since electrons are present outside the nucleus, it's always easy to remove or add electrons--but not the protons which are present inside the nucleus. An ion containing a positive charge, dur to the loss of one or more electrons, is called a cation. A negatively charge ion, due to the addition of one of more electrons, is called an anion. A molecule is a single particle composed of nonmental atoms. The atoms are held together by covalent bonds and share valence electrons. For example, water is a molecule composed of hydrogen and oxygen gas. If a metal is attracted to a nonmental, they are called ionics and are held together through ionic bonding. They have strong bonds, and thus have high melting points in order to break the bonds. These are also able to conduct electricity. An element is a substance that cannot be broken down through chemical reaction. There are over 100 known elements. Most are solids or gases at room temperature. A compound is two or more elements bonded together. A compound has a different physical and chemical property from the elements it is made out of. Compounds are difficult to split and can only be taken apart into their elements through chemical reactions or electrolysis. Binary compounds are composed of two elements only. For example, CO (carbon monoxide) is made up of only carbon and oxygen.

SMR 2.5.c: Demonstrate knowledge of the principle of conservation of energy, including analyzing energy transfers.

Energy refers to the capacity to do work. In other words, energy is responsible for moving matter against natural forces such as gravity and/or friction. There are two main categories of energy--kinetic energy and potential energy. We'll look at a few of the forms of energy that apply to heat transfer and thermodynamics. Anything that moves, from atoms to planets, contains the form of energy known as kinetic energy, the energy of motion. Examples of objects or matter possessing kinetic energy include: water running through pipes, electrons flowing along a copper wire, the contraction of leg muscles, and light that can be captured to perform work, such as photosynthesis in green plants. Heat, or thermal energy, is the kinetic energy available from random motion of molecules. The faster the movement of the molecules in a given system, the higher the amount of thermal energy or heat that system contains. Objects which are at rest and not presently at work may still contain energy, which, as stated earlier, is the capacity to do work. Matter at rest has the potential to do work by using its stored energy. This type of stored energy, or potential energy, is the energy matter contains because of its location or its given structural state. For example, water in the pipes when the faucet is turned off contains potential energy. Nuclear energy, or the energy that holds together atomic nuclei, is a form of potential energy which can be released when the nuclei are either split apart (nuclear fission) or combined (nuclear fusion). The sun creates its heat and light through nuclear fusion. A form of potential energy especially important to biologists is chemical energy. Chemical energy is energy stored in molecules due to the structural arrangement of the atoms within molecules. Every time energy is transferred or transformed from one type to another, the overall system becomes less structured and more 'disordered.' Scientists use a quantity called entropy as a scale or measure of disorder or randomness. The more disordered or random a system becomes, the more its entropy. This is also known as The Second Law of Thermodynamics. The Law of Conservation of Energy (also known as The First Law of Thermodynamics) states that: - The overall energy in a given system is interchangeable (i.e. thermal or heat energy can flow from one object to another). It also states that: - The energy within the universe is constant. Thus, energy can be transferred and transformed from one form of energy to another, but it can neither be created nor destroyed. This directly applies to heat transfer. Objects which have a higher thermal energy (i.e., heat energy) are said to also have a higher kinetic energy (i.e., energy of motion) of the molecules which make up the object itself. As the heat transfers to the molecules which are in a state of lower kinetic energy or potential energy (i.e., energy of position), the surrounding molecules will tend to increase in kinetic energy and decrease in potential energy. Thus, the energy flows from one object to another. https://uciunex.instructure.com/courses/9475/pages/refresher-conservation-of-energy?module_item_id=480716

SMR 1.1.a: Demonstrate knowledge of how to ask questions that can be addressed by scientific investigation, help further understanding of observed phenomena, and help clarify scientific explanations and relationships.

From NGSS: A practice of science is to ask and refine questions that lead to descriptions and explanations of how the natural and designed world works and which can be empirically tested. - Ask questions that require sufficient and appropriate empirical evidence to answer. - Ask questions that arise from careful observation of phenomena, models, or unexpected results, to clarify and/or seek additional information. - Ask questions to identify and/or clarify evidence and/or the premise(s) of an argument. - Ask questions to determine relationships between independent and dependent variables and relationships in models. - Ask questions to clarify and/or refine a model, an explanation, or an engineering problem. - Ask questions that can be investigated within the scope of the classroom, outdoor environment, and museums and other public facilities with available resources and, when appropriate, frame a hypothesis based on observations and scientific principles. - Define a design problem that can be solved through the development of an object, tool, process or system and include multiple criteria and constraints, including scientific knowledge that may limit possible solutions. - Ask questions that challenge the premise(s) of an argument or the interpretation of a data set. Students at any grade level should be able to ask questions of each other about the texts they read, the features of the phenomena they observe, and the conclusions they draw from their models or scientific investigations. Scientific questions arise in a variety of ways. They can be driven by curiosity about the world, inspired by the predictions of a model, theory, or findings from previous investigations, or they can be stimulated by the need to solve a problem. Scientific questions are distinguished from other types of questions in that the answers lie in explanations supported by empirical evidence, including evidence gathered by others or through investigation. A student can ask a question about data that will lead to further analysis and interpretation. Or a student might ask a question that leads to planning and design, an investigation, or the refinement of a design. https://ngss.nsta.org/Practices.aspx?id=1

SMR 1.2.a: Apply knowledge of engineering practices to define problems, determine specifications of designed systems, and identify constraints.

From NGSS: A practice of science is to ask and refine questions that lead to descriptions and explanations of how the natural and designed world works and which can be empirically tested. - Ask questions to clarify and/or refine a model, an explanation, or an engineering solution. For engineering, they should ask questions to define the problem to be solved and to elicit ideas that lead to the constraints and specifications for its solution. While science begins with questions, engineering begins with defining a problem to solve. However, engineering may also involve asking questions to define a problem, such as: What is the need or desire that underlies the problem? What are the criteria for a successful solution? Other questions arise when generating ideas, or testing possible solutions, such as: What are the possible tradeoffs? What evidence is necessary to determine which solution is best? When engaged in science or engineering, the ability to ask good questions and clearly define problems is essential for everyone. https://ngss.nsta.org/Practices.aspx?id=1

SMR 1.3.d: Apply knowledge of how systems are defined and studied and of how system models are used to make predications.

From NGSS: A system is an organized group of related objects or components; models can be used for understanding and predicting the behavior of systems. - Models can be used to represent systems and their interactions--such as inputs, processes and outputs--and energy and matter flows within systems. - Systems may interact with other systems; they may have sub-systems and can be a part of larger complex systems. - Models are limited in that they only represent certain aspects of the system under study. Systems and System Models are useful in science and engineering because the world is complex, so it is helpful to isolate a single system and construct a simplified model of it. "To do this, scientists and engineers imagine an artificial boundary between the system in question and everything else. They then examine the system in detail while treating the effects of things out the boundary as either forces acting on the system or flows of matter and energy across it--for example, the gravitational force due to Earth on a book lying on a table or the carbon dioxide expelled by an organism. Consideration of flows into and out of the system is a crucial element of system design. In the laboratory or even in field research, the extent to which a system under study can be physically isolated or external conditions controlled is an important element of the design of an investigation and interpretation of results...The properties and behavior of the whole system can be very different from those of any of its parts, and large systems may have emergent properties, such as the shape of a tree, that cannot be predicted in detail from knowledge about the components and their interactions." "Models can be valuable in predicting a system's behaviors or in diagnosing problems or failures in its functioning, regardless of what type of system is being examined...In a simple mechanical system, interactions among the parts are describable in terms of forces among them that cause changes in motion or physical stresses. In more complex systems, it is not always possible or useful to consider interactions at this detailed mechanical level, yet it is equally important to ask what interactions are occurring (e.g., predator-prey relationships in an ecosystem) and to recognize that they all involve transfers of energy, matter, and (in some cases) information among parts of the system...Any model of a system incorporates assumptions and approximations; the key is to be aware of what they are and how they affect the model's reliability and precision. Predictions may be reliable but not precise or, worse, precise but not reliable; the degree of reliability and precision needed depends on the use to which the model will be put." https://ngss.nsta.org/CrosscuttingConcepts.aspx?id=4

SMR 1.1.h: Demonstrate the ability to evaluate scientific arguments in terms of their supporting evidence and reasoning.

From NGSS: Argumentation is the process by which explanations and solutions are reached. - Compare and critique two arguments on the same topic and analyze whether they emphasize similar or different evidence and/or interpretations of facts. - Respectfully provide and receive critiques about one's explanations, procedures, models and questions by citing relevant evidence and posing and responding to questions that elicit pertinent elaboration and detail. - Construct, use, and/or present the oral and written argument supported by empirical evidence and scientific reasoning to support or refute an explanation or a model for a phenomenon or a solution to a problem. - Make an oral or written argument that supports or refutes the advertised performance of a device, process, or system, based on empirical evidence concerning whether or not the technology meets relevant criteria and constraints. - Evaluate competing design solutions based on jointly developed and agreed-upon design criteria. The study of science and engineering should produce a sense of the process of argument necessary for advancing and defending a new idea or an explanation of a phenomenon and the norms for conducting such arguments. In science, reasoning and argument based on evidence are essential in identifying the best explanation for a natural phenomenon. In engineering, reasoning and argument are needed to identify the best solution to a design problem. As such, argument is a process based on evidence and reasoning that leads to explanations acceptable by the scientific community and design solutions acceptable for the engineering community. Scientists and engineers engage in argumentation when investigating a phenomenon, testing a design solution, resolving questions about measurements, building data models, and using evidence to evaluate claims. https://ngss.nsta.org/practices.aspx?id=7

SMR 1.1.d: Apply modeling and mathematical concepts of statistics and probability to the analysis and interpretation of data, including analysis of errors and their origins.

From NGSS: Because data patterns and trends are not always obvious, scientists use a range of tools--including tabulation, graphical interpretation, visualization, and statistic analysis--to identify the significant features and patterns in the data. Modern technology makes the collection of large data sets much easier, providing secondary sources for analysis. - Consider limitations of data analysis (e.g., measurement error), and/or seek to improve precision and accuracy of data with better technological tools and methods (e.g., multiple trials). Because raw data as such have little meaning, a major practice of scientists is to organize and interpret data through tabulating, graphing, or statistical analysis. Such analysis can bring out the meaning of data--and their relevance--so that they may be used as evidence. Analysis of this kind of data not only informs design decisions and enables the prediction or assessment of performance but also helps define or clarify problems, determine economic feasibility, evaluate alternatives, and investigate failures. As students mature, they are expected to expand their capabilities to use a range of tools for tabulation, graphical representation, visualization, and statistical analysis. https://ngss.nsta.org/Practices.aspx?id=4

SMR 1.3.b: Analyze cause-and-effect relationships and their mechanisms in natural phenomena and engineered systems.

From NGSS: Events have causes, sometimes simple, sometimes multifaceted. Deciphering causal relationships, and the mechanisms by which they are mediated, is a major activity of science and engineering. - Cause and effect relationships may be used to predict phenomena in natural or designed systems. - Phenomena may have more than one cause, and some cause and effect relationships in systems can only be described using probability. - Relationships can be classified as causal or correlational, and correlation does not necessarily imply causation. - Cause and effect relationships can be suggested and predicted for complex natural and human designed systems by examining what is known about smaller scale mechanisms within the system. "In engineering, the goal is to design a system to cause a desired effect, so cause-and-effect relationships are as much a part of engineering as of science. Indeed, the process of design is a good place to help students begin to think in terms of cause and effect, because they must understand the underlying causal relationships in order to devise and explain a design that can achieve a specified objective." At early ages, this involves "doing" something to the system of study and then watching to see what happens. At later ages, experiments are set up to test the sensitivity of the parameters involved, and this is accomplished by making a change (cause) to a single component of a system and examining, and often quantifying, the result (effect). https://ngss.nsta.org/CrosscuttingConcepts.aspx?id=2

SMR 1.3.c: Apply knowledge of the concepts of scale, proportion, and quantity to describe and compare natural and engineered systems.

From NGSS: In considering phenomena, it is critical to recognize what is relevant at different size, time, and energy scales, and to recognize proportional relationships between different quantities as scales change. - Time, space, and energy phenomena can be observed at various scales using models to study systems that are too large or too small. - Proportional relationships (e.g., speed as the ratio of distance traveled to time taken) among different types of quantities provide information about the magnitude of properties and processes. - Phenomena that can be observed at one scale may not be observable at another scale. - The observed function of natural and designed systems may change with scale. - Scientific relationships can be represented through the use of algebraic expressions and equations. Scale, Proportion, and Quantity are important in both science and engineering. An understanding of scale involves not only understanding systems and processes vary in size, time span, and energy, but also different mechanisms operate at different scales. In engineering, "no structure could be conceived, much less constructed, without the engineer's precise sense of scale...At a basic level, in order to identify something as bigger or smaller than something else--and how much bigger or smaller--a student must appreciate the units used to measure it and develop a feel for quantity." "The ideas of ratio and proportionality as used in science can extend and challenge students' mathematical understanding of these concepts." The crosscutting concept of Scale, Proportion, and Quantity figures prominently in the practices of "Using Mathematics and Computational Thinking" and in "Analyzing and Interpreting Data." Scale and proportion are often best understood using models. For example, the relative scales of objects in the solar system or of the components of an atom are difficult to comprehend mathematically (because the numbers involved are either so large or so small), but visual or conceptual models make them much more understandable (e.g., if the solar system were the size of a penny, the Milky Way galaxy would be the size of Texas). https://ngss.nsta.org/CrosscuttingConcepts.aspx?id=3

SMR 1.3.a: Apply knowledge of patterns characteristic of natural phenomena and engineered systems.

From NGSS: Observed patterns in nature guide organization and classification and prompt questions about relationships and causes underlying them. - Different patterns may be observed at each of the scales at which a system is studied and can provide evidence for causality in explanations of phenomena. - Macroscopic patterns are related to the nature of microscopic and atomic-level structure. - Graphs, charts, and images can be used to identify patterns in data. - Patterns in rates of change and other numerical relationships can provide information about natural systems. - Patterns can be used to identify cause-and-effect relationships. - Patterns of performance of designed systems can be analyzed and interpreted to reengineer and improve the system. "Patterns exist everywhere--in regularly occurring shapes and structures and in repeating events and relationships. For example, patterns are discernible in the symmetry of flowers and snowflakes, the cycling of the seasons, and the repeated base pairs of DNA." While there are many patterns in nature, they are not the norm since there is a tendency for disorder to increase (e.g., it is far more likely for a broken glass to scatter than for scattered bits to assemble themselves into a whole glass). It is in such examples that patterns exist and the beauty of nature is found. "Noticing patterns is often a first step to organizing phenomena and asking scientific questions about why and how the patterns occur." "Once patterns and variations have been noted, they lead to questions; scientists seek explanations for observed patterns and for the similarity and diversity within them. Engineers often look for and analyze patterns, too. For example, they may diagnose patterns of failure of a designed system under test in order to improve the design, or they may analyze patterns of daily and seasonal use of power to design a system that can meet the fluctuating needs." Patterns figure prominently in the science and engineering practice of "Analyzing and Interpreting Data." Recognizing patterns is a large part of working with data. Students might look at geographical patterns on a map, plot data values on a chart or graph, or visually inspect the appearance of an organism or mineral. The crosscutting concept of patterns is also strongly associated with the practice of "Using Mathematics and Computational Thinking." It is often the case that patterns are identified best using mathematical concepts. The human brain is remarkably adept at identifying patterns, and students progressively build upon this innate ability throughout the school experiences. https://ngss.nsta.org/CrosscuttingConcepts.aspx?id=1

SMR 1.1.e: Demonstrate ability to analyze scientific data and information and draw appropriate and logical conclusions.

From NGSS: Scientific investigations produce data that must be analyzed in order to derive meaning. Because data patterns and trends are not always obvious, scientists use a range of tools--including tabulation, graphical interpretation, visualization, and statistical analysis--to identify the significant features and patterns in the data. Scientists identify sources of error in their investigations and calculate the degree of certainty in the results. Modern technology makes the collection of large data sets much easier, providing secondary sources for analysis. - Construct, analyze, and/or interpret graphical displays of data and/or large data sets to identify linear and nonlinear relationships. - Use graphical displays (e.g., maps, charts, graphs, and/or tables) of large data sets to identify temporal and spatial relationships. - Distinguish between causal and correlational relationships in data. - Analyze and interpret data to provide evidence for phenomena. - Apply concepts of statistics and probability (including mean, median, mode, and variability) to analyze and characterize data, using digital tools when feasible. - Consider limitations of data analysis (e.g., measurement error), and/or seek to improve precision and accuracy of data with better technological tools and methods (e.g., multiple trials). - Analyze and interpret data to determine similarities and differences in findings. - Analyze data to define an optimal operational range for a proposed object, tool, process or system that best meets criteria for success. Once collected, data must be presented in a form that can reveal any patterns and relationships and allows results to be communicated to others. Because raw data as such have little meaning, a major practice of scientists is to organize and interpret data through tabulating, graphing, or statistical analysis. Such analysis can bring out the meaning of data--and their relevance--so that they may be used as evidence. Engineers often analyze a design by creating a model or prototype and collecting extensive data on how it performs, including under extreme conditions. Analysis of this kind of data not only informs design decisions and enables the prediction or assessment of performance but also helps define or clarify problems, determine economic feasibility, evaluate alternatives, and investigate failures. Students are also expected to improve their abilities to interpret data by identifying significant features and patterns, use mathematics to present relationships between variables, and take into account sources of error. When possible and feasible, students should use digital tools to analyze and interpret data. Whether analyzing data for the purpose of science or engineering, it is important students present data as evidence to support their conclusions. https://ngss.nsta.org/Practices.aspx?id=4

SMR 1.1.i: Demonstrate knowledge of the ability to obtain, evaluate, interpret, and communicate scientific information (e.g., determining central ideas, integrating information from multiple sources, evaluating the validity of claims, using multiple formats to communicate scientific results).

From NGSS: Scientists and engineers must be able to communicate clearly and persuasively the ideas and methods they generate. Critiquing and communicating ideas individually and in groups is a critical professional activity. - Critically read scientific texts adapted for classroom use to determine the central ideas and/or obtain scientific and/or technical information to describe patterns in and/or evidence about the natural and design world(s). - Integrate qualitative and/or quantitative scientific and/or technical information in written text with that contained in media and visual displays to clarify claims and findings. - Gather, read, synthesize information from multiple appropriate sources and assess the credibility, accuracy, and possible bias of each publication and methods used, and describe how they are supported or not supported by evidence. - Evaluate data, hypotheses, and/or conclusions in scientific and technical texts in light of competing information or accounts. - Communicate scientific and/or technical information (e.g., about a proposed object, tool, process, system) in writing and/or through oral presentations. Being a critical consumer of information about science and engineering requires the ability to read or view reports of scientific or technological advances or applications (whether found in the press, or the Internet, or in a town meeting) and to recognize the salient ideas, identify sources of error and methodological flaws, distinguish observations from inferences, arguments from explanations, and claims from evidence. Scientists and engineers employ multiple sources to obtain information used to evaluate the merit and validity of claims, methods, and designs. Communicating information, evidence, and ideas can be done in multiple ways: using tables, diagrams, graphs, models, interactive displays, and equations as well as orally, in writing, and through extended discussions. https://ngss.nsta.org/Practices.aspx?id=8

SMR 1.2.d: Demonstrate knowledge of the process used to optimize a design solution (e.g., prioritizing criteria, refining a design due to test results).

From NGSS: The core idea of engineering design includes three component ideas: A. Defining and delimiting engineering problems involves stating the problem to be solved as clearly as possible in terms of criteria for success, and constraints or limits. B. Designing solutions to engineering problems begins with generating a number of different possible solutions, then evaluating potential solutions to see which ones best meet the criteria and constraints of the problem. C. Optimizing the design solution involves a process in which solutions are systemically tested and refined and the final design is improved by trading off less important features for those that are more important. At the middle school level, students learn to sharpen the focus of problems by precisely specifying criteria and constraints of successful solutions, taking into account not only what needs the problem is intended to meet, but also the larger context within which the problem is defined, including limits to possible solutions. Students can identify elements of different solutions and combine them to create new solutions. Students at this level are expected to use systematic methods to compare different solutions to see which best meet criteria and constraints, and to test and revise solutions a number of times in order to arrive at an optimal design. https://www.nextgenscience.org/sites/default/files/Appendix%20I%20-%20Engineering%20Design%20in%20NGSS%20-%20FINAL_V2.pdf

SMR 1.2.e: Apply knowledge of the interdependence of science, engineering, and technology (e.g., in agriculture, health care, and communications).

From NGSS: The fields of science and engineering are mutually supportive, and scientists and engineers often work together in teams, especially in fields at the borders of science and engineering. Advances in science offer new capabilities, new materials, or new understandings of processes that can be applied through engineering to produce advances in technology. Advances in technology, in turn, provide scientists with new capabilities to probe the natural world at larger or smaller scales; to record, manage, and analyze data; and to model ever more complex systems with greater precision. In addition, engineers' efforts to develop or improve technologies often raise new questions for scientists' investigations. The interdependence of science--with its resulting discoveries and principles--and engineering--with its resulting technologies--includes a number of ideas of how the fields of science and engineering interrelate. One is the idea that scientific discoveries enable engineers to do their work. For example, the discoveries of grand explorers of electricity have enabled engineers to create a world linked by vast power grids that illuminate cities, enable communications, and accomplish thousands of other tasks. Engineering accomplishments also enable the work of scientists. New insights from science often catalyze the emergence of new technologies and their applications, which are developed using engineering design. In turn, new technologies open opportunities for new scientific investigations. https://www.nextgenscience.org/sites/default/files/APPENDIX%20J%204.15.13%20for%20Final%20Release.pdf

SMR 1.1.g: Demonstrate the ability to construct and analyze scientific explanations.

From NGSS: The products of science are explanations and the products of engineering are solutions. - Construct an explanation that includes qualitative or quantitative relationships between variables that predict(s) and/or describe(s) phenomena. - Construct an explanation using models or representations. - Construct a scientific explanation based on valid and reliable evidence obtained from sources (including the students' own experiences) and the assumption that theories and laws that describe the natural world operate today as they did in the past and will continue to do so in the future. - Apply scientific ideas, principles, and/or evidence to construct, revise and/or use an explanation for real-world phenomena, examples, or events. - Apply scientific reasoning to show why the data or evidence is adequate for the explanation or conclusion. - Apply scientific ideas or principles to design, construct, and/or test a design of an object, tool, process, or system. - Undertake a design project, engaging in the design cycle, to construct and/or implement a solution that meets specific design criteria and constraints. - Optimize performance of a design by prioritizing criteria, making tradeoffs, testing, revising, and re-testing. The goal of science is to construct explanations for the causes of phenomena. Students are expected to construct their own explanations, as well as apply standard explanations they learn about from their teachers or readings. The goal of science is the construction of theories that provide explanatory accounts of the world. An explanation includes a claim that relates how a variable or variables relate to another variable or a set of variables. Asking students to demonstrate their understanding of the implications of a scientific idea by developing their own explanations of phenomena, whether based on observations they have made or models they have developed, engages them in an essential part of the process by which conceptual change can occur. In engineering, the goal is a design rather than an explanation. The process of developing a design is iterative and systematic, as is the process of developing an explanation or theory in science. https://ngss.nsta.org/practices.aspx?id=6

SMR 1.3.f: Analyze the relationship between structure and function in natural and engineered systems.

From NGSS: The way an object is shaped or structured determines many of its properties and functions. - Structures can be designed to serve particular functions by taking into account properties of different materials, and how materials can be shaped and used. - Complex and microscopic structures and systems can be visualized, modeled, and used to describe how their function depends on the shapes, composition, and relationships among its parts, therefore complex natural structures/systems can be analyzed to determine how they function. Structure and Function are complementary properties. The shape and stability of structures of natural and designed objects relate to their function(s). The functioning of natural and built systems alike depends on the shapes and relationships of certain key parts as well as on the properties of the materials from which they are made. For example, the substructures of molecules are not particularly important in understanding the phenomenon of pressure, but they are relevant to understanding why the ratio between temperature and pressure at constant volume is different for different substances. "Similarly, understanding how a bicycle works is best addressed by examining the structures and their functions at the scale of, say, the frame, wheels, and pedals. In this way, the builder can seek less dense materials with appropriate properties; this pursuit may lead in turn to an examination of the atomic-scale structure of candidate materials." https://ngss.nsta.org/CrosscuttingConcepts.aspx?id=6

SMR 1.2.f: Demonstrate knowledge of the influence of engineering, technology, and science on society and the natural world (e.g., in land use, transportation, and energy production).

From NGSS: Together, advances in science, engineering, and technology can have--and indeed have had--profound effects on human society, in such areas as agriculture, transportation, health care, and communication, and on the natural environment. Each system can change significantly when new technologies are introduced, with both desired effects and unexpected outcomes. From the earliest forms of agriculture to the latest technologies, all human activity has drawn on natural resources and has had both short- and long-term consequences, positive as well as negative, for the health of both people and the natural environment. These consequences have grown stronger in recent human history. Society has changed dramatically, and human populations and longevity have increased, as advances in science and engineering have influenced the ways in which people interact with one another and with their surrounding natural environment. Not only do science and engineering affect society; society's decisions (whether made through market forces or political processes) influence the work of scientists and engineers. These decisions sometimes establish goals and priorities for improving or replacing technologies; at other times they set limits, such as in regulating the extraction of raw materials or in setting allowable levels of pollution from mining, farming, and industry. https://www.nextgenscience.org/sites/default/files/APPENDIX%20J%204.15.13%20for%20Final%20Release.pdf

SMR 1.3.e: Apply knowledge of the flow, cycling, and conservation of energy and matter to analyze natural and engineered systems.

From NGSS: Tracking energy and matter flows, into, out of, and within systems helps one understand their system's behavior. - Matter is conserved because atoms are conserved in physical and chemical processes. - Energy may take different forms (e.g., energy in field, thermal energy, energy of motion). -Within a natural system, the transfer of energy drives the motion and/or cycling of matter. - The transfer of energy can be tracked as energy flows through a natural system. - Changes of energy and matter in a system can be described in terms of energy and matter flows into, out of, and within that system. - Energy drives the cycling of matter within and between systems. Energy and Matter are essential concepts in all disciplines of science and engineering, often in connection with systems. "In many systems there also are cycles of various types. In some cases, the most readily observable cycle may be matter--for example, water going back and forth between Earth's atmosphere and its surface and subsurface reservoirs." "Consideration of energy and matter inputs, outputs, and flows or transfers within a system or process are equally important for engineering." https://ngss.nsta.org/CrosscuttingConcepts.aspx?id=5

SMR 4.1.d: Demonstrate knowledge of nuclear fusion in stars, including the relationship between a star's mass and stage of its lifetime and the elements produced.

Fusion in stars produces energy, including visible light radiated from the surface of a star, and forms new elements. Fusion occurs in the center or core of a star, where the pressure and temperature are highest. The high temperature and pressure ensure that particles--always nuclei since the high temperature strips electrons from neutral atoms--come together with enough energy to overcome the electric forces that would otherwise keep them apart.The minimum temperature to ignite fusion is about 10 million K. Inside the Sun, a typical star, the core temperature is about 15 million degrees K. In stars like the Sun, which is of average mass and about halfway through its 10 billion year life span, the fusion reaction is primarily the "burning" of hydrogen into helium. Four hydrogen nuclei--that is, four protons--form one helium nucleus (two protons and two neutrons), plus neutrinos and the release of energy. The four hydrogen nuclei do not all join at once, however. The reaction proceeds in a chain called the proton-proton chain.

SMR 2.3.c: Identify the separate forces that act on a system (e.g., gravity, tension/compression, normal force, friction), describe the net force on the system, and describe the effect of the stability of the system.

Gravity is the force of attraction between two objects which have mass. The pressure on an object is the force exerted by a liquid, solid, or gas on a unit area of the object (solid, liquid, or gas). The smaller the area the pressure force acts on, the greater the pressure. Another force that acts on a body is tension. Tension occurs when equal and opposite forces are applied to the ends of an object and pull the object apart. The molecules are held together by intermolecular forces of attraction. Compression is the force opposite of tension. the force also has an equal and opposite force that is applied to the ends of an object that decreases the length of an object. This force is opposed by the intermolecular force of attraction. Normal force may be the most common force that acts on a body. It occurs when two bodies are in direct contact with each other and are perpendicular to the body that applies the force. An example is a man standing on a platform. Gravity pushes the man down, while the platform counteracts the force pushed down on the man. This force is called normal force. This force is an example of Newton's Third Law--every force has an equal and opposite reaction). Friction is the force that acts to oppose the motion of two touching objects over each other. It is caused by the intermolecular force of attraction between the molecules of the surfaces. http://sciencecsetprep.weebly.com/forces-and-motions.html

SMR 2.4.e: Evaluate evidence that indicates that certain wavelengths of electromagnetic radiation may affect living things.

In addition to alpha particles, other types of radioactive decays produce other forms of radiation, originally labeled as "beta" and "gamma" particles and now recognized as electrons or positrons, and photons (i.e., high-frequency electromagnetic radiation), respectively. Because of the high-energy release in nuclear transitions, the emitted radiation (whether it be alpha, beta, or gamma type) can ionize atoms and may thereby cause damage to biological tissue. Electromagnetic radiation (such as light and X-rays) can be modeled as a wave of changing electric and magnetic fields. At the subatomic scale (i. e., in quantum theory), many phenomena involving electromagnetic radiation (e.g., photoelectric effect) are best modeled as a stream of particles called photons. Electromagnetic radiation from the sun is a major source of energy for life on Earth. By understanding wave properties and the interactions of electromagnetic radiation with matter, scientists and engineers can design systems for transferring information across long distances, storing information, and investigating nature on many scales—some of them far beyond direct human perception. When shorter wavelength electromagnetic radiation (ultraviolet, X-rays, gamma rays) is absorbed in matter, it can ionize atoms and cause damage to living cells. However, because X-rays can travel through soft body matter for some distance but are more rapidly absorbed by denser matter, particularly bone, they are useful for medical imaging. https://www.nap.edu/read/13165/chapter/9#137

SMR 3.3.c: Apply knowledge of energy flow, nutrient cycling, and matter transfer in ecosystems (e.g., food webs, biogeochemical cycles), including recognizing the roles played by photosynthesis and aerobic and anaerobic respiration.

Matter cycles between the air and soil and among plants, animals, and microbes as these organisms live and die. Organisms obtain gases, and water, from the environment, and release waste matter (gas, liquid, or solid) back into the environment. Food webs are models that demonstrate how matter and energy is transferred between producers, consumers, and decomposers as the three groups interact within an ecosystem. Transfers of matter into and out of the physical environment occur at every level. Decomposers recycle nutrients from dead plant or animal matter back to the soil in terrestrial environments or to the water in aquatic environments. The atoms that make up the organisms in an ecosystem are cycled repeatedly between the living and nonliving parts of the ecosystem. Photosynthesis and cellular respiration (including anaerobic processes) provide most of the energy for life processes. Plants or algae form the lowest level of the food web. At each link upward in a food web, only a small fraction of the matter consumed at the lower level is transferred upward, to produce growth and release energy in cellular respiration at the higher level. Given this inefficiency, there are generally fewer organisms at higher levels of a food web. Some matter reacts to release energy for life functions, some matter is stored in newly made structures, and much is discarded. The chemical elements that make up the molecules of organisms pass through food webs and into and out of the atmosphere and soil, and they are combined and recombined in different ways. At each link in an ecosystem, matter and energy are conserved. Photosynthesis and cellular respiration are important components of the carbon cycle, in which carbon is exchanged among the biosphere, atmosphere, oceans, and geosphere through chemical, physical, geological, and biological processes.

SMR 2.1.a: Analyze the basic substructure of an atom (i.e., protons, neutrons, and electrons).

The atom is largely empty space with electrons moving about. Within the center of the atom is the atomic nucleus. The nucleus is tiny and has very high density. Surrounding the nucleus are the electrons. This electron cloud constitutes most of the volume of the atom. Protons (p+) have a positive charge (+1) and a relative mass of 1. The number of protons identifies the element and equals the number of electrons, so atoms are electrically neutral. They are found in the nucleus with neutrons. Neutrons (n0) have a neutral charge (0) and a relative mass of 1. The number of neutrons in an atom can vary (the variation is what distinguishes isotopes) and they are found in the nucleus with protons. Electrons (e-) have a negative charge (-1) and a relative mass of 1/1836. They have a very tiny mass and they move around the nucleus in electron shells. Electron shells are the regions of space around the nucleus. An atom can have up to 7 shells called K, L, M, N, O, P, and Q. Each shell holds up to a certain number of electrons with the first shell holding 2 and each subsequent one holding up to 8. The further away the shell is from the nucleus, the higher the energy of its electrons (the shells close to the nucleus are more stable). If the very last shell, called the outer shell, is full or has 8 electrons (octet), then the atom is stable. Each shell consists of orbital, or probability, clouds, and the positions of electrons cannot be exactly determined at any one time. The mass number (A) is the number of protons and neutrons in the nucleus. The atomic number (Z) is the number of protons in a nucleus. The atomic number (N) is the number of neutrons subtracting the atomic number from the mass number. The atomic weight is the total number of particles in an atom's nucleus.

SMR 3.1.a: Demonstrate understanding that a small subset of elements (C, H, O, N, P, S) makes up most of the chemical compounds in living organisms by combining in many ways.

The elements, C (carbon), H (hydrogen), O (oxygen), N (nitrogen), P (phosphorus), and S (sulfur) are the most common elements found in living organisms. Because carbon contains four valence electrons, it can form four covalent bonds. Molecules containing carbon can form straight chains, branches, or rings. This allows many possibilities to generate a range of molecular structures and shapes. Carbon always wants to hold onto four other atoms or groups of molecules. This allows for tremendous diversity and variety of molecules based on the C atom attached to other atoms. Pretty much all living things are built around carbon-based molecules. http://sciencecsetprep.weebly.com/molecular-biology-and-biochemistry.html

SMR 3.1.b: Recognize and differentiate the structure and function of molecules in living organisms, including carbohydrates, lipids, proteins, and nucleic acids.

There are four classes of macromolecules: carbohydrates, lipids, proteins, and nucleic acids. Macromolecules are polymers, which are molecules built by linking together a large number of small, similar chemical subunits. For example, complex carbohydrates are polymers of simple ring-shaped sugars. Proteins are polymers of amino acids. Nucleic acids (DNA and RNA) are polymers of nucleotides. Macromolecules are grouped into four major categories: carbohydrates, proteins, lipids, and nucleic acids. Carbohydrates are made up of one simple subunit called a monosaccharide that is then joined together to form disaccharides (sucrose and lactose) and polysaccharides (cellulose and starch). Carbohydrates are comprised of carbon, hydrogen, and oxygen with a ratio of 1:2:1. Carbohydrates are essential for energy storage and structural support. Lipids are made of glycerol, fatty acids, phosphates, long carbon chains, and more. This is a group of esters including fats and waxes found in living tissue. Lipids are insoluble in water, but soluble in organic solvents. The most familiar lipids are fats and oils. They have a very high proportion of nonpolar carbon-hydrogen bonds, as a result, these long-chain lipids cannot fold up like a protein. When placed in water, many lipid molecules will cluster together and expose the polar groups to the surrounding water while hiding away the nonpolar parts of the molecules together within this cluster. This setup is very important to cells as it underlies the structure of cellular membranes. Lipids are a source of energy, chemical messengers, insulation, and crucial elements of membranes. Proteins are macromolecules whose subunit are amino acids joined together in a peptide chain. They are only 20 amino acids, each with a hydrogen, an amino group, a carboxyl group, and an R group (composed of varying molecules). Provides structure, acts as a catalyst in biological systems, provides support, movement, growth, and repair. Nucleic acids are macromolecules whose subunits are nucleotides. Two different nucleic acids are called DNA and RNA and they are found in cells' nuclei (RNA is also found in the cytoplasm). There are five nitrogenous bases: adenine, guanine, uracil (found only in RNA), thymine (found only in DNA), and cytosine. There are three components: a five carbon sugar, a phosphate group, and a nitrogenous group. The nucleic acid is comprised of chains of 5 carbon sugars that are linked by a phosphate bond, which is an organic base protruding from each sugar. If the sugar is deoxyribose, then the polymer is a DNA. If the sugar is a ribose, then the polymer is an RNA. Nucleic acids carry the genetic code in DNA and RNA. Their function is to encode genes and gene expression. http://sciencecsetprep.weebly.com/molecular-biology-and-biochemistry.html

SMR 2.3.e: Identify fundamental forces, including gravity, nuclear forces, and electromagnetic forces (magnetic and electric), and recognize their roles in nature, such as the role of gravity in maintaining the structure of the universe.

There are four fundamental forces that govern what happens in the universe: gravity, nuclear force, electromagnetic force, and weak force. Gravity acts like glue, holding stars, planets, and galaxies together. Gravity causes dispersed materials to coalesce (i.e., in the formation of our solar system); it is responsible for keeping planets and comets in orbit around the sun; it is responsible for keeping satellites in orbit; gravity causes tides; gravity helps control a star's temperature, allowing the start to expand when its core temperature increases and increases the force of gravitation if the star's core temperature cools too much; and is a dynamic process that helps shape the Earth through processes such as weathering, erosion, and plate tectonics. Nuclear force is the force responsible for binding protons and neutrons in the nucleus. This residual strong force prevents repulsion between protons from pushing the nucleus apart. This force is very strong--the strongest of the four fundamental forces--but has a short range. Electromagnetic force, unlike gravity, depends on electrical charge instead of mass. It is carried via photons and holds atoms and molecules together. It effects positively and negatively charged particles. Both magnetic and electric forces are a result of photon exchanges. In electric forces, like charges repel, and in magnetic forces, like and unlike repel. The weak force plays a role in nuclear reactions, fusion and fission. It is also the only force, besides gravity, that effects neutrinos. It also plays a role in radioactive decay. http://sciencecsetprep.weebly.com/forces-and-motions.html

SMR 2.4.a: Compare the characteristics of mechanical and electromagnetic waves (e.g., transverse/longitudinal, travel through various media, relative speed).

There are two main types of waves: mechanical and electromagnetic. Mechanical waves are waves that oscillate and transfer energy through mediums. They transport energy only. There is no material that is transported through mechanical waves. These waves can only be produced in media which possesses elasticity and inertia. Electromagnetic waves are waves consisting of oscillating electric and magnetic fields. They can travel through most media including a vacuum. The electromagnetic spectrum is a range of electromagnetic waves, in order of increasing wavelength and decreasing frequency. Examples include gamma rays, x-rays, ultraviolet radiation, visible light, infrared radiation, microwaves, and radio waves. Waves can move in different manners. Transverse waves are waves where particles oscillate perpendicular (right angled) to the direction that the wave is moving in. An example of a transverse wave would be holding a piece of paper or a rope and moving your hand up or down. Transverse waves are unable to pass through liquids or gases. They are able to travel through only solid mediums, as they require a rigid medium in order to travel. All electromagnetic waves are transverse. Mechanical waves can be transverse. Longitudinal waves are known as "l" waves. Mechanical longitudinal waves are also called compressional waves. Particles move in a direction parallel to the direction that the wave moves. They transport energy from left to right, forward and backwards. Unlike transverse waves, longitudinal waves are able to travel through liquids, gases, and solids. Sound waves are longitudinal waves. Sound waves can travel through solids, liquids, and gases. They are unable to travel through a vacuum of space due to the lack of medium to carry the vibrations. The speed at which sound waves move depends on the medium they are travelling through. Light waves are electromagnetic waves, which are always transverse waves. Light waves are produced by the Sun and by any heated object until it glows (called incandescence). Different wavelengths in the waveband produce different colors. Seismic waves travel out in all directions from the focus (location of the energy source within the Earth). There are three types of seismic waves: primary (P), secondary (S), and surface waves. P waves are longitudinal waves and can travel through solids, liquids, and gases. S waves are transverse waves and can travel through solids only. Surface waves have an up-and-down motion and side-to-side. They travel like many S waves or they may travel like rolling ocean waves and travel only through the crust. P waves travel the fastest and surface waves travel the slowest. http://sciencecsetprep.weebly.com/waves.html

SMR 2.5.e: Apply knowledge of heat transfer by conduction, convection, and radiation, including analyzing examples of each mode of heat transfer.

Transfer of thermal energy is caused primarily through conduction, convection, or radiation. Heat transfer is always directed from a higher to a lower temperature. Metals are generally good conductors of heat because thermal energy easily travels through them. Conduction is the transfer of thermal energy through matter from one atom or molecules to another. The atoms or molecules don't move from one place to another. Instead the energy is transferred from one atom or molecule to another by the electrons that hold them together. For example, a spoon in a cup of hot tea becomes warmer because the heat from the hot liquid is conducted along the spoon from metal atom to metal atom by electrons in the metal. Conduction is most effective in solids, but it can happen in fluids as well. Fun Fact! Have you ever noticed that metals such as aluminum or silver tend to feel cold? In reality, they are not colder! They only feel colder because they conduct heat away from your body or hand. You perceive the heat that is leaving your hand as cold. Convection, the transfer of thermal energy in a fluid, is due to the motion of the atoms or molecules from place to place. This results in actual motion of the fluid. Convection can also take place in some solid matter as well, such as sand. For example, convection is responsible for making pasta rise and fall in a pot of heated water. The warmer portions of the water are less dense and as result, they rise to higher levels. At the same time, the cooler portions of the water travel to lower portions of the pot because they are denser. Radiation is a transfer of thermal energy caused by electromagnetic waves that are emitted from objects such as the sun or light bulbs. Radiation does not involve the motion of electrons, atoms, molecules or any other type of matter--only the transfer of energy from one place to another. Sunlight is a type of radiation that carries energy through space to our planet. X-rays and Infrared rays are two other types of radiation, which travel through space to our planet as well. The energy travels through completely empty space! Consider this! The sun transfers radiant heat through 93 million miles of space in order to reach planet Earth. Since there are no solids in space (like a huge metal spoon) touching the sun and our planet, conduction cannot be responsible for transferring heat to planet Earth. Since there are no fluids (like air and water) in space, convection cannot be responsible for transferring heat either. It is radiation from the sun that directly brings heat to our planet. Fire is another way to create radiation. The energy released from the chemical bonds within the burning material is converted into radiation that travels through space even though no atoms or molecules leave the fire. Fire is another kind of radiation, in which energy is released from the chemical bonds within the material. https://uciunex.instructure.com/courses/9475/pages/refresher-conduction-convection-and-radiation?module_item_id=480726

SMR 2.2.d: Analyze chemical bonding with respect to an element's position in the periodic table.

Valence electrons: Are found in the outer regions of an atom. They are found in the most distant s and p energy subshell. These electrons are responsible for holding two or more atoms together in a chemical bond. According to the octet rule, atoms tend to bond in such a way that they acquire 8 electrons in its outer shell. This can occur by transfer of electrons from one atom to another--by sharing. Ionic bond: Occurs when a metal cation is attracted to a nonmetal anion. These are held together by the attraction of opposite charges. Fundamental particles held together by ionic bond are called formula units. Covalent bond: Two nonmetals share valence electrons. A fundamental particle held together by covalent bonds is a molecule. When a metal atom loses its valence electrons, it becomes positively charged forming a cation. So, if Na, n group 1, loses an electron, it becomes Na+ and only has 10 electrons, the same as Ne (a noble gas). We call this isoelectronic, when main group metals achieve a noble gas configuration after losing one or more electrons. Anions are achieved when a nonmetal gains valence electrons and thus becomes negatively charged. For example, when Cl atom gains one valence electron (group 18) it becomes Cl- and now has 19 electrons, the same as Ar. Because the cation loses an electron, its radius becomes smaller because there is less pull from the nucleus. Anions become larger because they gain an electron and there is now less pull towards the nucleus. Covalent: The electrons from the nonmetals belong to both and are shared to produce an octet to complete their valence shells. Since the valence shell is filled, the bond is stable. For example, in HCl, the hydrogen atom shares one of its valence electrons with the Cl atom. This gives Cl eight electrons in its outer valence shell, thus making it isoelectronic with Ar and stable. Ar shares one of its valence electrons with H, giving it 2 electrons in its outer shell. H becomes isoelectronic with He, making both elements stable. http://sciencecsetprep.weebly.com/structure-and-properties-of-matter.html

SMR 2.5.b: Demonstrate knowledge of the ways in which energy manifests itself at the macroscopic level (e.g., motion, sound, light, thermal energy).

When things are moving, they have kinetic energy. The food you eat has potential energy. Everything is made up of small particles. When the particles are moving faster, there is more energy and the temperature is higher. As fast-moving particles touch slow-moving particles, the energy is transferred. This is how conduction and thermal energy work. Light is the energy that travels in waves and is produced by hot, energetic objects. If you have ever touched a lightbulb while it is on, you know it is hot. You know the light bulb needs energy because you have to turn the light switch on to provide electricity for it. Sound is a form of energy that causes particles to vibrate back and forth. The loudness or intensity of a sound depends on the energy used. The more energy used, the louder the sound. You use a lot more energy to yell than you do to whisper. The same is true with all sounds: the more energy expended, the louder the sound. One way the three forms of energy are alike is that they can be reflected. Energy waves can also be refracted, bent. Heat, light, and sound are similar to each other. They are forms of energy and they travel in waves. https://www.uen.org/core/science/sciber/TRB6/downloads/06literacy.pdf