Bio Midterm Study Guides Questions

Explain the difference between a food chain and a food web.

A food chain shows the flow of energy through a series of steps as organisms feed on other organisms. A food web shows all the possible combinations of organisms feeding on each other and are much more complicated than food chains.

Explain how abiotic factors influence an ecosystem.

A natural disaster can negatively affect an ecosystem. Changing ph levels or temperature can also affect an organism. An organism has certain ranges in which these abiotic factors need to fall in for them to survive, and these are a part of their niche.

Explain why ecosystems usually only have no more than 4-5 trophic levels.

At each level, 10% of the energy is lost, and therefore there is not enough energy left to sustain any more trophic levels at around 4-5.

Identify the different levels of organization that ecologist study.

Atom, molecule, macromolecule, organelle, cell, tissue, organ, organ system, organism, population, community, ecosystem, biome, biosphere

Define biodiversity and explain its value.

Biodiversity is the total of all the genetically based variation in all organisms in the biosphere. All the variety benefits us with different medicines and agriculture, as well as some goods and services.

Give an example of resource partitioning.

Certain birds use different parts of the same tree to feed on insects. They aren't getting in each other's way, so competition is nonexistent.

Identify the six different elements needed by living things to make organic compounds.

Carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur

Explain the important role of decomposers in the flow of energy in ecosystems.

Decomposers are extremely important to the flow of energy. They break down dead matter that other animals would otherwise be unable to obtain, and it would therefore be lost. They break down the dead matter into detritus, which can then be fed upon by the detritivores. Detritivores can then be eaten by other consumers and it is once again back in the cycle.

Differentiate between density dependent and independent factors.

Density dependent factors change depending on density of the populations. These include disease, predation, competition, herbivory, stress from overcrowding, and parasitism.

Identify factors that limit population growth.

Disease, parasitism, competition, predation, lack of nutrients, food, water, incorrect environmental conditions, natural disasters, bad weather. These are limiting factors.

Trace the flow of energy through living systems.

Energy flows through an ecosystem in a one-way stream, from primary producers to various consumers.

Identify factors that affect population size.

Growth rate- births, deaths, immigrations, emigrations Biotic potential (+) - reproductive rate, ability to migrate, defensive mechanisms, ability to live in wide range of conditions Environmental resistance (-) - lack of food, water, nutrients and suitable habitat, predators, competition, disease, parasites

Describe how the availability of nutrients affects the productivity of ecosystems.

If a nutrient is in short supply it will limit the nutrients growth, or their "primary productivity." If a nutrient is suddenly much more available, then an algal bloom may occur. The producers can grow much quicker, and sometimes too quick for the consumers to keep up, which may cause an equilibrium.

Identify the three types of community interactions that occur within communities.

Predation, competition, and symbiosis

Explain the role of producers and consumers in the flow of energy in ecosystems.

Producers capture their own energy by taking in sunlight or in some cases by using chemicals. This turns the energy into an easily accessible source for producers, which they receive by eating the plants.

Give an example of an introduced species and describe the problem it creates.

Rabbits in Australia grew to 20 billion in a few decades. Tried to lower the population with a virus but now many are immune. They grow out of control and take up many resources that other species need, and if they have no predators they will keep on growing.

Describe how resource partitioning minimizes competition between species.

Since species are not all competing for the same food, one doesn't have to die off as a result of not getting enough resources. If they each go for a different resource, then there is no loser, and no competition.

Explain why population growth rates differ in countries throughout the world.

Some countries are developed and therefore have higher life expectancies and less child mortalities, meaning they don't need as many children and have more elderly people. However, in developing countries people don't live as long and there are higher child mortality rates, meaning they need to have more children and have less elderly people.

Identify the source of energy for life processes.

Sun

Explain the competitive exclusion principle.

The competitive exclusion principle explains that no two species can occupy the same niche in the same habitat at the same time. One will always win more resources and thrive, and the other will always die off and be unable to survive due to the lack of resources.

Explain demographic transition and give examples of countries in different stages of demographic transition.

The drastic change from high birth rates and high death rates, to low birth rates and low death rates in developed countries. •Stage 1- both are high; Afghanistan, some parts of Africa •Stage 2- death rates fall as technology/nutrition/medicine improves, birth rates remain the same and population booms; South American Africa and Asia •Stage 3- as living standards rise families have less kids and birth rates go down, slowing population growth; USA, Japan, Europe

Describe the goal of conservation biology.

The goal of conservation biology is to protect certain species, preserve ecosystems and habitats, and make sure that humans near conservation areas benefit from the efforts.

Explain how Earth's climate maintained.

The greenhouse effect. The greenhouse gases in our atmosphere allow some heat in and reflects some heat. It then allows some more out, but traps some inside, which regulates our climate. The gases are methane, Carbon dioxide, nitrous oxide, ozone, and water vapor.

Define endosymbiosis and explain why it is important in the history of eukaryotes.

Theory that eukaryotic cells came from symbiosis among several different prokaryotic organisms. Prokaryotes that could use oxygen to generate ATP became mitochondria and those that carried out photosynthesis became chloroplasts. This is what created eukaryotic cells, the symbiosis of these prokaryotic cells. It gave them the energy needed to carry out cell processes.

Describe how biotic potential and environmental resistance help regulate population size.

They form an equilibrium. If a population gets too large, then environmental resistance kicks in and the population is lowered. For instance, disease or parasitism could increase as a population gets larger. If it gets too small, animals reproduce more or develope better defense mechanisms to bring the population up.

Explain how matter cycles among the living and nonliving parts of an ecosystem.

Through Biogeochemical cycles. Elements pass from organism to organism and through other non living parts of an ecosystem through closed systems powered by energy. Energy is never created, it is just rearranged. Biological processes consist of all activities performed by living organisms, like breathing and eating. Geological processes happen with non living parts of an ecosystem, such as a volcanic eruption or the breakdown of rock. Chemical and physical processes also happen with non living parts, such as lightning, precipitation, cloud formation, and running water.

Explain how the Law of Limiting Factors impacts organisms.

Too much or too little of an abiotic factor can limit or prevent growth of a population or species. If an abiotic factor is outside the range of tolerance of an organism for too long, it may result in death.

Identify Earth's three main climate zones.

Tropical, temperate, and polar

Evaluate the efficiency of energy transfer among organisms in an ecosystem.

Very inefficient, with just 10% being passed on each level. This is due to heat loss, excretion, energy lost to body processes, and organisms that aren't consumed.

Describe the difference between abiotic and biotic factors in an ecosystem and give examples of each.

•Abiotic- nonliving: temperature, precipitation, natural disasters, ph, sunlight •Biotic- living: disease, competition, predation, herbivory, symbiosis, reproducing, animals, plants

State the cell theory.

•All living things are composed of cells •Cells are the basic units of structure and function in living things •New cells are produced from existing cells

Identify and explain the five threats to biodiversity and the impact each has on organisms.

•Altering habitats- habitat fragmentation; can split habitats and make populations smaller and more vulnerable •Hunting- can hunt species to extinction Invasive species- reproduce extremely quickly and can use up many resources, also have no natural predators usually •Pollution- can poison animals, especially with biological accumulation and magnification •Climate change- changing the climates of habitats of animals can kill them off, like with the law of limiting factors. Especially if habitat fragmentation occurs and they can't get to a suitable habitat

Distinguish between autotrophs/heterotrophs, producers/consumers, herbivores, omnivores, carnivores, decomposers and detritus feeders.

•Autotrophs- capture energy on their own, usually from the sun •Heterotrophs- must consume other organisms to obtain their energy •Producers- autotrophs; capture energy on their own •Consumers- heterotrophs; must consume other organisms to obtain their energy •Herbivores- only feed on plants; usually primary consumers •Carnivores- only feed on animals- usually secondary or higher consumers •Omnivores- eat a combination of plants and animals; can be primary consumers or up •Consumers- break down dead matter into detritus •Detritivores- feed on dead matter, or detritus

Identify the different shapes of bacteria.

•Bacilli- rod-shaped •Cocci- spherical •Spirilla- corkscrew/spiral shaped •Can be in colonies, chains, or individual

Growth and reproduction of bacteria.

•Binary fission- asexual form of reproduction where cell replicates DNA and divides in half •Conjugation- sexual form of reproduction where hollow bridge is formed between two cells and genes are transferred, increases genetic diversity •Spore formation- endospores form when an organism is exposed to bad conditions, can remain dormant for many months or years and enclose DNA and some cytoplasm

Explain the difference between biomagnification and bioaccumulation.

•Biomagnification happens as organisms eat other organisms and the harmful substances within them are concentrated as it goes up the food chain. The predators at the top are at the greatest risk. •Bioaccumulation occurs in a single organism, as the amount of harmful substances increase in them over time.

Explain how each nutrient is important to living things.

•Carbon- important for making tissues like animal skeletons, and is found in lipids, proteins, carbs, and nucleic acids. Very easy to bond with •Nitrogen- found in amino acids which make up proteins for body structures like muscles, and make up enzymes, and nucleic acids •Hydrogen- found in water, which is essential to life, and is also found in lipids, carbs, proteins, and nucleic acids •Oxygen- found in water, and lipids, nucleic acids, carbs, and proteins •Phosphorus- found in nucleic acids, which make up RNA and DNA •Sulfur- found in proteins, which make amino acids and enzymes, as well as muscle

Explain how the two kingdoms of prokaryotes differ.

•Eubacteria: Wide variety of organisms. Live almost anywhere. Surrounded by cell wall containing peptidoglycan, a carbohydrate. Some are pathogenic. •Archaebacteria: Have cell walls, lack nuclei, and are small like eubacteria, but are very different. Lack peptidoglycan, and have different membrane lipids from any other organism (I think they are linked). Live in extreme environments and DNA is more similar to that of eukaryotes.

Differentiate between exponential and logistic growth and the resulting graphs.

•Exponential: occurs when there are ideal conditions and unlimited resources. Animals grow at very fast, exponential rate until resources are depleted. J curve on graph. •Logistic: a slower growth as population reaches its carrying capacity and birth rate slows/death rate rises. Stops growing altogether once it reaches its carrying capacity. S curve on graph.

List the characteristics used to describe a population.

•Geographic range/distribution: where organisms live and how they live together- 3 types of distribution are uniform, clumped, and random •Population density- amount of individuals per unit area; how densely populated they are; affected by biotic potential and environmental resistance •Growth rate- how fast a population is growing; number of births, number of deaths, and number of immigrants/emigrants affect growth rate; J curve and S curve •Age structure: how old certain populations are

Describe the factors that affect population size.

•Growth rate- births, deaths, immigrations, emigrations •Biotic potential (+) - reproductive rate, ability to migrate, defensive mechanisms, ability to live in wide range of conditions •Environmental resistance (-) - lack of food, water, nutrients and suitable habitat, predators, competition, disease, parasites

Describe the role climate, latitude and altitude play in determining what type of biome exists.

•Latitude- the higher the latitude the less direct the Sun's rays are and therefore the lower the temperature. •As altitude increases, the temperature also declines, as does life living at these heights. •Precipitation and temperature also have an effect as to what biomes exist. For instance a high temperature, low precipitation biome would be a desert, where as a low temperature high precipitation biome would be the poles, and grasslands would fall in the middle for both.

Compare and contrast the function and magnifying ability of the light microscope, scanning microscope and transmission electron microscope.

•Light microscope: Up to 1500x magnification. Uses two or more magnifying glasses to magnify objects. Used to view cells, and can view live specimens •Scanning microscope: Up to 60,000x magnification. Uses electromagnets to sweep beam of electrons over specimen and photons bounce back to produce image. 3-D images of surface cells and tissues. Used in vacuum. •Transmission microscope: Up to 100,000x magnification. Explore cell structures and large protein molecules. Need extremely thin cell/tissue slices to work. Specimens must be in vacuum

Identify the different types of symbiosis and give examples of each.

•Mutualism: both organisms benefit- a bee and a pollinating flower; the bee gets the nectar and the plants are pollinated •Commensalism: one organism benefits and the other is not harmed- barnacles on a whale; barnacles get food from moving water and whale seems unaffected •Parasitism: one organism benefits while the other is harmed- ticks and many organisms- ticks feed off their host and give them diseases in return

Describe the ways that bacteria can obtain energy.

•Photoautotroph- use photosynthesis for energy and carbon, light is energy source •Photoheterotrophs- use light for energy and take in organic compounds for carbon •Chemoautotrophs- perform chemosynthesis where energy source is chemicals (inorganic compounds) •Chemoheterotrophs- take in organic molecules for energy and carbon •Obligate aerobes (releasing energy)- require constant supply of energy to live (obligate means required to live that way) •Obligate anaerobes (releasing energy)- require absence of oxygen to live •Facultative anaerobes (releasing energy)- don't require oxygen, but can still live in it (facultative means able to function in different ways)

Describe how ecosystems recover from a disturbance.

•Primary succession: when there is no soil in an area, pioneer species like mosses or lichen move into the area and slowly turn it into a more habitable place. Before long, other organisms start to grow as well and soil builds up, creating a brand new ecosystem. •Secondary succession: occurs after a fire or human influence. Certain species begin to grow again in the soil remaining and eventually it returns to as it once was before. Takes much less time than primary succession. •Turn back into a stable, "climax" community

Describe the similarities and differences between prokaryotes and eukaryotes.

•Prokaryotes have genetic information not stored in a nucleus. They are also usually much smaller and less complicated. Often contain less organelles. •Eukaryotes have genetic information stored in a nucleus. They are generally more complicated and larger. They contain far more organelles and structures, and show a greater variety.

Interpret age-structure diagrams.

•Rectangle- developed country •Slim triangle- country developing slowly •Wide triangle- country developing more rapidly •Upside down triangle- country with a negative growth rate

Describe the factors used to identify prokaryotes.

•Shape ~Bacilli-rod ~Cocci-spheres ~Spirilla-spiral •Cell walls- Gram staining ~Two dyes, violet (primary) and red (counter) ~Primary stain sticks to peptidoglycan cell walls ~If still there when washed then Gram-positive, thick wall ~If not then Gram-negative, thin wall, stained by counter •Movement ~Flagellar- use of one or more flagella, same direction ~Spiral ~Tumbling- multiple flagella, reverse direction ~Sessile- adheres to surface •How they obtain energy ~Photoautotroph- use photosynthesis for energy and carbon, light is energy source ~Photoheterotrophs- use light for energy and take in organic compounds for carbon ~Chemoautotrophs- perform chemosynthesis where energy source is chemicals (inorganic compounds) ~Chemoheterotrophs- take in organic molecules for energy and carbon ~Obligate aerobes (releasing energy)- require constant supply of oxygen to live (obligate means required to live that way) ~Obligate anaerobes (releasing energy)- require absence of oxygen to live ~Facultative anaerobes (releasing energy)- don't require oxygen, but can still live in it (facultative means able to function in different ways)

Explain why bacteria are vital to maintaining the living world.

•Some are producers that create energy for consumers through photosynthesis •Some are decomposers who break down dead organisms and recycle nutrients to maintain an equilibrium, sewage treatment •Perform nitrogen fixation to convert nitrogen gas into a form plants can use, some have symbiotic relationships with plants •Human uses

Match each of the scientists that contributed to the cell theory with their contribution.

•Theodor Schwann- all animals made up of cells, basic unit of living things •Matthias Schleiden- all plants made up of cells, basic unit of living things •Rudolph Virchow- all cells come from preexisting cells

Describe the difference between top-down and bottom-up regulation of population.

•Top-down regulation is when the population is affected by the predator. Like if more wolves are brought into an area to bring down rabbit populations or if wolves go extinct in an area and rabbit populations boom •Bottom-up regulation is when the population is affected by the resources. Like if rabbits were wiped out from an area wolves would starve or if there were great amounts of rabbits in an area then the wolves would have lots to eat.

Explain the goals of environmental science.

•Understand how natural world works •Understand how human and nature systems interact •Accurately assess the status and trends of crucial natural ecosystems •Establish long term sustainable relationships with the natural world

List three ways that bacteria are helpful to humans.

•Used in production of foods and beverages •Clean up oil spills and other pollutants/wastes •Help mine minerals from the ground •Help create drugs (genetic engineering) •Ones like E. coli help us create vitamins

Explain how humans are impacting each nutrient cycle.

•Water cycle- mostly pollution of the water so it cannot be used •Carbon cycle- our massive usage of fossil fuels and combustion of them into CO2 in our atmosphere. •Nitrogen cycle- the fertilizer we manufacture to increase plant growth, as well as planting legumes •Phosphorus- also used in fertilizers

Describe what is unique about each nutrient cycle (water, carbon, nitrogen, phosphorus).

•Water- doesn't need to pass through a single organism to go through the entire cycle. Like most, water can be in the atmosphere, on land, in the ocean, and in the ground, although it comes out of the atmosphere without any influence by organisms. •Carbon- we have possibly the biggest impact on it, with all of the fossil fuels we use in our daily life. Unlike any of the other cycles, Carbon can be pulled straight from the atmosphere into a producer through photosynthesis, and then can be taken in by consumers through feeding. Can also be found in the ocean. •Nitrogen- although the greatest store of nitrogen is found in the atmosphere, it cannot be directly taken in by producers. It must first be fixated by either bacteria on legumes or lightening, and then (if it's fixed by plants) must go through nitrifying bacteria in order to become usable by plants in the form of nitrates, NO3. Can then be consumed by consumers. Often the limiting nutrient in oceans. •Phosphorus- only one without any in the atmosphere. Most stored in rocks and is weathered and taken up by plants or runs off streams into the ocean. Often the limiting nutrient in rivers, streams, and lakes.

Describe the difference between r-strategists and K-strategists.

•r-strategists usually grow exponentially. They usually have a shorter life span, reproduce just once but with a lot of offspring, give little/no parental care to their young, have an unstable environment, a smaller body size, and less total energy. •K-strategists usually grow logistically. They usually live longer, have less offspring, give more parental care, are larger, have more energy, reproduce multiple times, and live in a stable environment.