BIO Exam 1

Leiden

Netherlands

Eukaryotic cells

have a membrane bound nucelus

Which of the following structures is conserved in all living organisms and points to a common origin?

All living organisms store genetic material in DNA/RNA.

Prokaryotic cells are found in the domain(s) _____.

Bacteria and Archaea

segments of DNA

Barbara McClintock discovered transposons while working on maize genetics. What are the transposons composed of when they are able to shift from one location to another?

What property of carbon makes it essential for organic life?

Carbon can form up to four covalent bonds, allowing it to form carbon chains.

How many neutrons do carbon-12 and carbon-13 have, respectively?

Carbon-12 contains 6 neutrons while carbon-13 contains 7 neutrons.

atomic mass

calculated mean of the mass number for its naturally occurring isotopes.

Louis Pasteur's hypothesis

cells arise from cells

What makes a chemical reaction spontaneous?

if they proceed on their own, without any continuous external influence such as added energy

Which of these provides evidence of the common ancestry of all life?

near universality of the genetic code

prokaryotic cell

no membrane bound nucleus

At which level of protein structure are interactions between the side chains (R-groups) most important?

tertiary

Pedanius Dioscorides

wrote De Materia Medica, used for 1500 years before Carl Linnaeus.

Lucretius

wrote De rerum natura (On the nature of things) about Epicureanism - all things are made of atoms. More about physics.

Why is each element unique with respect to its chemical properties? Each element has a distinctive ________.

# of protons

Each of the figures above represents a peptide with three amino acids linked together (a "tripeptide"). In which figure are the N-terminus, C-terminus, Amino Group, and Carboxyl Group correctly labeled?

(left to right, top then bottom) N-terminus, C-terminus, amino group, side chains, Carboxyl group (A)

This atom can form up to _____ single covalent bond(s).(4 valence electrons)

4

Which one of these is an amino group?

NH2

How many electrons are involved in a single covalent bond?

two

Antonie van Leeuwenhoek

-Cell vacuole-Protists -Bacteria -Muscle Fibers

From its atomic number of 15, it is possible to predict that the phosphorus atom has ________.

15 protons and 15 electrons

Although the scientific method is used by most of the sciences, it can also be applied to everyday situations. A situation is given below. Using the scientific method try to arrange the given steps in the correct order. Situation: If the car doesn't start the problem might be in the battery. Car doesn't start. After changing the battery. Car starts working. The car should start after charging the battery or changing the battery. The car doesn't start because the battery is dead. The car doesn't start even after charging the battery, the battery must have stopped working.

2, 1, 5, 4, 6, 3

Explain why researchers formulate a null hypothesis in addition to a hypothesis when designing an experimental study.

A null hypothesis specifies what a researcher should observe when the hypothesis being tested isn't correct.

stabilizing selection

A population of rodents settles on the shore of an island close to the Arctic Circle. The landscape consists mainly of rocks. If the individuals are too large, they cannot hide in crevices to escape hawks. On the other hand, small bodies do not maintain internal temperature in cold weather. Show diagrammatically the change in the population and explain what selective pressures took place.

A poorly conserved gene would be a good choice, because poorly conserved genes undergo sufficient changes during relatively short times, which allows for the study of recent evolutionary events.

A scientist decides to investigate the evolutionary connection between closely related bacteria. Make a claim as to which gene would be a good choice to use for establishing relatedness, a very well conserved gene or a poorly conserved gene. Provide appropriate reasoning to defend your claim.

Implications of cell theory- evolution

All of the cells present in a multicellular organism have descended from preexisting cells And are connected by common ancestry

Limestone is a naturally occurring mineral rich in calcium carbonate (CaCO3). In water, calcium carbonate dissolves to form carbonate (CO32−), a weak base that acts as a buffer. Which would you expect to be more affected by acid rain, an environment rich in limestone or an environment poor in limestone?

An environment poor in limestone would be more affected by acid rain.

The rabbit and human belong to the clade of animals with hair. The amniotic egg evolved before hair.

Analyze the figure provided to answer the following: Which of the animals shown belong to a clade that includes animals with hair? Which evolved first, hair or the amniotic egg?

The pedometer hypothesis states

Ants always know how far they are from the nestBecause they track the number of steps taken And they know length of their stride

Aphids have acquired the ability to make carotenoids due to the horizontal transfer of fungal genes into the insect, likely as the insect consumed fungi for food.

Aphids are a group of insects that vary in color, a trait that depends on their carotenoid content. Explain the evolutionary adaptation or mechanism that allowed aphids to acquire the ability to change color.

Both astronomy and astrology study the stars. Which one is considered a natural science? Explain your reasoning.

Astronomy is a natural science as it deals with observations and prediction of events in the sky, which is based on the laws of physics.

Cats and dogs are in the same group beginning at the Domain level and including the sublevels Kingdom, Phylum, Class, and Order.

At what levels are cats and dogs considered to be part of the same group?

How does a chaperone work with proteins?

Chaperones assist proteins in folding.

The protein sequence of cytochrome c from chimpanzees and humans is identical. The protein sequence of cytochrome c from rhesus monkeys differs from the human sequence by one amino acid. What do these comparisons suggest?

Chimpanzees are more closely related to humans than rhesus monkeys.

Carbohydrates serve various functions in different animals. Arthropods like insects, crustaceans, and others, have an outer layer, called the exoskeleton, which protects their internal body parts. This exoskeleton is made mostly of chitin. Chitin is also a major component of the cell walls of fungi, the kingdom that includes molds and mushrooms. Chitin is a polysaccharide. What is the major difference between chitin and other types of polysaccharides?

Chitin is a nitrogen-containing polysaccharide, with repeating units of N-acetyl-ββ-D-glucosamine, a modified sugar.

Based on this small amount of DNA sequence data, which species do you predict is most closely related to Pink salmon? Draw a model and circle the letter differences to help you derive your answer.

Chum salmon

The statement "Various species of Galapagos finches are adapted to their particular habitats" means

Different species have traits that increase fitness in a particular environment.

Analogous-Dolphins are mammals and fish are not, thus their evolutionary paths are quite separate. They have similar body shapes because of their similar environments.

Dolphins and fish have similar body shapes. Appy your understanding of processes that shape similarities among organisms to state whether this feature is more likely a homologous or an analogous trait. Support your answer with relevant reasoning.

The French scientist Jacques Monod famously said, "Anything found to be true of E. coli must also be true of elephants." How is this statement based on the notion that living organisms share a common ancestor?

E. coli is a prokaryote. The various metabolic processes and core functions in E. coli share homology with higher organisms.

Nitrogen (N) is more electronegative than hydrogen (H). Which of the following is a correct statement about the atoms in ammonia (NH3)?

Each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge.

Miller Urey Experiment

Early simulated atmosphere created amino acids. More advanced experiments have even made nucleobases found in DNA and RNA.

University of Munich

Early specialtiesWell funded=Had 200 instructors related to the fieldHad the first physiology labStudied tissue (was originally the simplest structure).

Animals cannot digest cellulose due to the type of bonding between the glucose monomers. The glucose monomers are there for an energy source but are unattainable. Yet ruminants such as cows and sheep, and termites eat cellulose in the form of grasses and wood. How do they do it?

Specialized bacteria and protists are found in the digestive tracts of these animals making cellulase that result in cellulose breakdown.

Which of these describe some of the similarities and differences between glycogen and starch?

Starch is less branched than glycogen and is found in plants.

This is an example of convergent evolution.

The emu in Australia and ostrich in Africa are flightless birds that look similar. One proposed hypothesis was the birds descend from an early common ancestor that spread when the continents were connected. DNA analysis shows that emus and ostriches share more genetic homology with flying birds which live in the same region than with each other. What is the best explanation for these findings?

Fiber is not really a nutrient, because it passes through our body undigested. Why can't fiber be digested and why is it important to our diet?

The enzymes required to digest cellulose are not produced in human body; undigested fiber adds bulk to the food easing bowel movements.

zebra

The fossil of a long bone is discovered in a sediment. The shape of the bone is similar to the shape of a tibia in modern horses. The results from DNA analysis show the following percentage similarity of conserved regions of the cytochrome c oxidase gene.

Dehydration is a word usually used to mean the removal of water. How does this apply to macromolecules?

The hydroxyl groups of two monomers are used to form a bond by removing a hydrogen from one monomer and a hydroxyl group from the second forming a molecule of water.

For many years, no one bothered to test the food-competition hypothesis for why giraffes have long necks. Why?

The hypothesis was so plausible that no one thought to question it.

Gram-negative bacteria likely have conserved genes from both Archaea and gram-positive bacteria through symbiosis.

The image shows a model of the hypothetical evolution of the cell membrane of gram-negative bacteria, which has a double membrane. Make a claim stating what this hypothesis predicts about the genetics of gram-negative bacteria.

List the mass number and atomic number of carbon-12 and carbon-13, respectively.

The mass number and atomic number of carbon-13 is 13 and 6, while that of carbon-12 is 12 and 6, respectively.

Describe the pH scale and how it relates to living systems. Give an example of how drastic pH changes are prevented in living systems.

The pH scale ranges from 0 to 14, where anything below 7 is acidic and above 7 is alkaline. The bicarbonate system in the human body buffers the blood.

Fish, frogs, and lizards do all possess a hinged jaw; however, only lizards possess an amniotic egg.

The phylogeny pictured shows the evolution of traits in vertebrates. Based on this phylogeny, a student asks "Does this mean that fish, frogs, and lizards all possess a hinged jaw and amniotic eggs at some point in their evolution?" Evaluate the phylogeny, then select the most accurately reasoned answer to the student's question.

Why do long distance runners "carbo load" before a race?

They eat foods high in starch, a polysaccharide, because they can be broken down slowly into monosaccharide to provide long lasting energy.

What is the importance of the nodes seen on the illustration of the phylogenetic tree seen here?

They show points during evolution when ancestors are believed to have broken off into two new species.

Phylum

Which of category, below the level of Kingdom, would have the next largest number of organisms?

Species

Which taxonomic classification levels would contain the most-similar organisms?

Homologous traits provide evolutionary history, but analogous traits do not.

Why do scientists identify homologous and analogous structures before building phylogenetic trees?

Could both the food competition hypothesis and the sexual competition hypothesis explain why giraffes have long necks? Why or why not?

Yes. Long necks could be advantageous for more than one reason.

About twenty-five of the 92 natural elements are known to be essential to life. Which 4 of these 25 elements make up approximately 96 percent of living matter?

carbon, hydrogen, nitrogen, oxygen

What type of bond is joining the two hydrogen atoms?

covalent

Isotopes

different forms of an element that have the same number of protons but a different number of neutrons. Some

Which of the following bodily process would most likely be hindered by a lack of water in the body?

digestion

What are two topics that are likely to be studied by biologists and two areas of scientific study that would fall outside the realm of biology?

diseases affecting humans, pollution affecting species habitat, calculating surface area of rectangular ground, functioning of planetary orbitals

A(n) _____ bond joins these two oxygen atoms.

double covalent

A water molecule can bond to up to _____ other water molecules by ____ bonds.

four... hydrogen

Consider the levels of organization of the biological world and place each of these items in order from smallest level of organization to most encompassing: skin cell, elephant, water molecule, planet Earth, tropical rainforest, hydrogen atom, wolf pack, liver.

hydrogen atom, water molecule, skin cell, liver, elephant, wolf pack, tropical rainforest, planet Earth

The structure of double helical DNA

is used to synthesize messenger RNA

Side chains of amino acids ________

may be polar or nonpolar

Athletes consume large amounts of energy to meet the needs of their high activity level. Carbohydrates are an excellent choice for delivering calories that quickly fuel the body. Which of the following would be the best source of energy for an athlete?

option with 6 c's(c)

The unequal sharing of electrons within a water molecule makes the water molecule _____.

polar

You are studying a protein that is shaped like a doughnut. The shape is a function of which level(s) of protein structure?

primary, secondary, and tertiary

Why are polymerization reactions endergonic? Polymerization reactions ________.

reduce entropy

What type of bond joins the carbon atom to each of the hydrogen atoms?

single (nonpolar) covalent

null hypothesis

specifies what we should observe if the hypothesis being tested does not hold

Jean-Baptiste Lamarck

taught courses

Which of the following can vary among monosaccharides?

the number of carbon atoms

atomic number

the number of protons in the nucleus of an atom

Louis Pasteur's experiment had a good design because

the possible outcomes led to distinct, unambiguous conclusions

mass number

the total number of protons and neutrons in the nucleus of an atom

What is the pH of a solution with a hydroxyl ion (OH−) concentration of 10−12 M?

two

State the number and type of bonds you'd expect electronegative Sulfur to form if it reacted with hydrogen.

two covalent polar bonds

What are three examples of how the characteristics of water are important in maintaining life?

First, the lower density of water as a solid versus a liquid allows ice to float, forming an insulating surface layer for aquatic life. Second, the high specific heat capacity of water insulates aquatic life or bodily fluids from temperature changes. Third, the high heat of vaporization of water allows animals to cool themselves by sweating.

Pasteur

Germ theory of diseaseDisproved spontaneous generation Proved cells come from other cells only-Completes cell theory.

Which of these best describes the production of sucrose, maltose, and lactose?

Glucose and fructose combine to form sucrose. Glucose and galactose combine to form lactose. Two glucose monomers combine to form maltose.

Glycolysis has been conserved despite the independent evolution of the three domains of life.

Glycolysis, or the breakdown of glucose, is a process used by almost all organisms as a way to release energy stored within glucose molecules. This energy can then be stored in cells as ATP, which powers cell processes when needed. What does this show, in terms of the evolutionary history of cells using glycolysis?

Looking at the above figure, can you infer which two groups together will form a strong ionic bond?

Group 1 and Group 17

Masatomo Kawakubo et al. reported in Science in August 2004 that the human stomach contains a natural, carbohydrate-based antibiotic that probably protects a large portion of the population from various diseases caused by the bacterium Helicobacter pylori. This bacterium has been linked to peptic ulcers, gastritis, and stomach cancer. This naturally occurring antibiotic is described by Kawakubo as having a terminal α-1,4-linked N-acetylglucosamine (NAG), and it acts by inhibiting the biosynthesis of a major component of the cell wall in H. pylori. [SOURCE: M. Kawakubo et al., Science 305 (2004): 1003.]Refer to the paragraph about Kawakubo's group. Kawakubo's group created a glycoprotein with a terminal NAG (i.e., a protein with NAG attached to its end). Their hypothesis is that the terminal NAG, and not the protein component, is responsible for the damage to the cell wall in H. pylori. What would be the most appropriate control for testing this hypothesis?

Grow H. pylori in a test tube with a glycoprotein that has its terminal NAG removed.

Which of these functional groups is characteristic of alcohol?

HO

Linnaeus' Taxonomic System of Classification

In 1735 Carolus Linnaeus established the classification system still in use todayEach organism is given a unique two-part scientific nameIt consists of the genus and the speciesA genus is Made up of a closely related group of species A species is made up ofIndividuals that regularly breed together Or individuals whose characteristics are distinct from those of other species

methionine-alanine-threonine-cysteine-tryptophan-glutamine-alanine-serine

In Bacterium A, the active site sequence of an enzyme has the following amino acid sequence: methionine-valine-threonine-cysteine-cysteine-glycine-alanine-histidine. The amino acid sequence of four other bacteria species is analyzed and presented below. Compare these to answer: Which of these bacteria is likely the most distantly related to Bacterium A?

The coloration in the population shifted toward more dark-colored beetles, as in diagram IV. The light-colored beetles were found more easily by predators than were the dark-colored beetles.

In a hypothetical population of beetles, the insects exhibit a wide variety of color, matching the range of coloration of the tree trunks on which the beetles hide from predators. The graphs shown illustrate four possible changes in the beetle population that occurred as a result of a change in the environment due to pollution that darkened the tree trunks. Predict the most likely change in the coloration of the beetle population after pollution, and support your answer with reasoning.

What is "selected" during natural selection?

Individuals with certain advantageous traits are selected, in the sense that they produce the most offspring.

Why can some insects walk on water?

Insects can walk on water because of its high surface tension.

What makes ionic bonds different from covalent bonds?

Ionic bond involves the transfer of electrons whereas covalent bond involves the sharing of electrons.

At about pH 7 in most cells, what happens to the amino R-group on an amino acid?

It acts as a base and gains a proton, giving it a positive charge.

Vegans are people who do not consume any animal products in their diet. Why do vegans need to pay special attention to the protein they eat?

It is more difficult to obtain all essential amino acids from single plant sources.

K-41 is one of the naturally occurring isotopes of potassium. Use the periodic table to explain how the structure of K-41 differs from the normal K atom.

K-41 has a total of 22 neutrons and normal K atom has 20 neutrons

Some plants called lithops grow in the South African desert and look like stones. How were scientists able to determine they are living organisms?

Lithops are autotrophic. They show growth and reproduction.

Systematics and taxonomy are two fields of study that contribute to scientists' understanding of phylogeny.

Make the connection between systematics, taxonomy, and phylogeny by explaining how the three fields relate to one another.

The Theory of Evolution by Natural Selection

Mid 1800s Darwin and Wallace

What does this figure demonstrate?(giraffe bending down to eat)

Most of the time, giraffes do not lift their necks fully when feeding.

Why are covalent bonds between hydrogen and nitrogen or oxygen polar?

Nitrogen and oxygen are more electronegative than hydrogen so electrons are shared unequally.

cytoplasm

One justification for phylogenetics is the evidence--if you go back far enough in evolutionary history--that all species are ultimately related to each other. Determine one feature that is shared by humans and prokaryotes due to those organisms' common ancestry.

What 4 elements are common to all living organisms?

Oxygen, Carbon, Nitrogen and Hydrogen

Which of these groups plays a major role in energy transfer?

PO4

Natural History Museum

Paris in 1635

Rudolph Virchow

Pathologist All cells from other cells-stolen from Robert Remak(replication). Site of disease, got cancer right Got germs wrong

The research team used DNA to uncover phylogenetic relationships in the legume family, and they found a DNA marker that can be used to screen for plants with potential medicinal properties.

Phylogeny is important to everyday life in human society. How did the research team in China use phylogeny as a guide to discover new plants that can be used to benefit people?

Which categories of amino acid would you expect to find on the surface of a soluble protein, and which would you expect to find in the interior?

Polar and charged amino acids will be found on the surface. Non-polar amino acids will be found in the interior.

The word hydrolysis is defined as the lysis of water. How does this apply to polymers?

Polymers break by separating water into hydrogen and hydroxyl group that are added to the monomers.

Which kingdom consists primarily of unicellular eukaryotes?

Protists

Which of the following is not an extracellular matrix role of carbohydrates?

Provide energy for muscle movement

Read the following questions. Does the statement lend itself to investigation using the scientific method? In other words, is the hypothesis falsifiable (can be proven false)? Is macaroni and cheese tastier than broccoli soup? Are hummingbirds attracted to the color red? Is the moon made out of green cheese? Is plagiarism dishonest?

Questions 1 and 4 are subjective and cannot be disproven using scientific method. Questions 2 and 3 can be tested using scientific method.

cell theory

Schwann and Schleiden Believed in cytoblastema-Cells formed outside cells

Scientists cannot go back across time to confirm proposed evolutionary relationships in phylogenetic trees.

Scientists use data from multiple sources to define phylogeny, yet phylogenetic trees are considered hypothetical. Justify this premise by offering an explanation to support why it is accepted.

Edinburgh

Scotland

There are cases where organisms evolved through convergence and appear closely related although they are not.

Some organisms that appear very closely related may not actually be closely related. Justify this claim by providing reasoning to support it.

How do organisms survive below freezing temperatures?The winter flounder (Pseudopleuronectes americanus) lives in the Mid-Atlantic Ocean and along the New England coast, where frigid water temperatures would normally turn the water inside the flounder's cells into ice. Does the flounder produce some type of antifreeze compound that prevents it from freezing solid? It does! P. americanus produces a small antifreeze protein (AFP) that binds to ice crystals as they form. The structure of AFP has polar groups on one side and nonpolar groups on the other. What is the most likely hypothesis to explain how AFP prevents cells from freezing solid.

AFP binds to ice crystals and forms a nonpolar shell that prevents hydrogen bonding between water molecules to form a larger crystal. By limiting crystal growth, the cell would not freeze solid.

Discuss how buffers help prevent drastic swings in pH

Buffers absorb excess hydrogen and hydroxide ions to prevent increases or decrease in pH. An example is the bicarbonate system in human body.

Phylogenetic trees can represent traits that are derived or lost due to evolution. One example is the absence of legs in some marine mammals. One such group is the Cetaceans, which includes toothed whales, such as dolphins and killer whales, and baleen whales, such as humpback whales. Cetaceans are descended from even-toed ungulates and share a common ancestry with the hippopotamus, cows, sheep, camel, and pig. Based on this phylogenetic tree, which of the following animal is the most closely related to a horse?

Cat

What three theories form the framework for modern biological science?

Cell theory, theory of evolution by natural selection, the chromosome theory of inheritance

What makes something alive?

Cells, replication, evolution, information, energy

What is structurally different between starch and cellulose that gives them different physical properties?

Cellulose is formed by β-1,4 glycosidic linkages and crosslinks, making it rigid. Starch has α-1.4 and α-1.6 glycosidic linkages without the tight crosslinks of cellulose.

The unique properties of water are important in biological processes. For the following three properties of water, define the property and give one example of how the property affects living organisms:cohesion adhesion high heat of vaporization

Cohesion is the attraction between the water molecules, which helps create surface tension. Insects can walk on water because of cohesion. Adhesion is the attraction between water molecules and other molecules. Water moving up from the roots of plants to the leaves as a result of capillary action is because of adhesion. Heat of vaporization is the amount of energy required to convert liquid into gas. This property helps humans maintain homeostasis of body temperature by evaporation.

Robert Hooke

Coined the term Cell, thought plantslooked like honeycomb cells. Dude made him a goldembossed microscope.

Organisms that share a category at lower levels (family, genus) are more closely related than those that share a higher-level category.

Comparing the descriptions below, select the one that most accurately explains how the levels of classification in the Linnaean system demonstrate the relationships between organisms.

The shape of hair proteins is maintained by a combination of hydrogen bonds and covalent, disulfide bonds. Heat is sufficient to break the hydrogen bonds, but harsh chemicals are required to break the disulfide bonds. Why is it harder to break the disulfide bonds than the hydrogen bonds?

Covalent bonds are stronger than hydrogen bonds.

IF THE PH OF BLOOD INCREASES, ONE WOULD EXPECT ________.

DECREASE IN THE CONCENTRATION OF H2CO3 AND AN INCREASE IN THE CONCENTRATION OF HCO3−

The taxonomic classification system uses a hierarchical model to organize living organisms. At each sublevel, the organisms are more similar.

Describe how organisms are classified in the taxonomic classification system.

One of the risks for people with diabetes is diabetic ketoacidosis, a build-up of acid in the blood stream. Explain why this is dangerous to humans.

Diabetic ketoacidosis decreases normal pH (7.35-7.45) to a lower value.

How do the differences in amino acid sequences lead to different protein functions?

Different amino acids produce different proteins based on the bonds formed between them.

How do the differences in amino acid sequence lead to different protein functions?

Different amino acids provide different geometric configurations and thus varied functions.

An atom may give, take, or share electrons with another atom to achieve a full valence shell, the most stable electron configuration. Looking at this figure, how many electrons do elements in group 1 need to lose in order to achieve a stable electron configuration? How many electrons do elements in groups 14 and 17 need to gain to achieve a stable configuration?

Elements of group 1 need to lose one electron, elements of group 14 need to gain 4 electrons, and elements of group 17 need to gain 1 electron

first law of thermodynamics

Energy can be transferred and transformed, but it cannot be created or destroyed.

A human is classified in domain _____ and kingdom _____.

Eukarya, Animalia

A rose bush is classified in domain _____ and kingdom _____

Eukarya, Plantae

Yes, because it suggests the eukaryotes possess traits that were likely conserved from prokaryotic ancestors.

Eukaryotic mitochondria contain their own DNA, known as mitochondrial DNA, or mtDNA. Nuclear and mitochondrial DNA are thought to be of different (separate) evolutionary origin, with the mitochondrial DNA being derived from the circular chromosomes of bacteria that were engulfed by ancient prokaryotic cells. Does the presence of mitochondrial DNA suggest that organisms share many conserved core processes and features that evolved and are widely distributed among organisms today? Why or why not?

Some hypotheses propose that mitochondria were acquired first. Others propose that the nucleus evolved first. Still others hypothesize that prokaryotes descended from eukaryotes by the loss of genes and complexity.

Evaluate the scenarios below that compare three different ways that eukaryotic cells may have evolved. Which comparison accurately identifies these hypotheses?

second law of thermodynamics

Every energy transfer or transformation increases the entropy of the universe.

Chloroplasts and mitochondria came about through endosymbiosis with gram-negative bacteria because these organelles have a double membrane.

Examine how the parts of the displayed figure relate to each other. Part b of the figure shows a hypothetical model of the evolution of the cell membrane of gram-negative bacteria, which has a double membrane. If this hypothesis is true, which explanation supports what it suggests about the evolution of mitochondria and chloroplasts in eukaryotic cells and explains why that is the case?

HGT is the transmission of genetic information from one unrelated species to another. It creates genetic variation through this exchange of genetic material amongst unrelated species, suggesting that mutations are not the only source of genetic variation.

Explain what horizontal gene transfer (HGT) is and its importance in genetic variation.

why do so many people avoid eating gluten?Gluten is a mixture of proteins abundant in wheat, barley, and rye. Although these grains are staples in the Western diet, almost 1 percent of Americans have celiac disease - a disorder of the intestines caused by an abnormal immune response after eating gluten. This immune response damages the fingerlike villi of the small intestine, which can lead to intestinal upset and malnourishment. Currently, the only treatment is to maintain a strict gluten-free diet. When you eat gluten, enzymes present in your stomach and intestines digest all but a few short peptides. How do enzymes accomplish this activity?

The active site of an enzyme binds to a gluten protein and facilitates the hydrolysis reaction that breaks apart peptide bonds.

Is the sugar in your soda affecting your mind?A 20-ounce soda typically contains 15 teaspoons of either sucrose or high-fructose corn syrup. These sugary beverages are a leading source of calories in the American diet and have been correlated with obesity and diabetes. There may be even more to this sweet dilemma, however. Could the sugars found in soda be altering your brain function?The effect of diet on human health is often evaluated using animal models. Researchers tested the impact of drinking fructose solutions on memory by using mice trained to find an escape chamber in a maze. The mice were fed diets consisting of control chow or chow that was supplemented with a fructose solution, omega-3 fatty acids, or both. After six weeks on the diets, the mice were tested again on the same maze with the results shown in the bar graph

The best diet for performance in your classes will be rich in omega-3 fatty acids and low in fructose.

Hair is only a characteristic found in the rabbit evolutionary history. The amniotic egg was possessed by both the rabbit and lizard, but not frogs, at some point in their evolutionary history.

The phylogeny pictured shows the evolution of traits in vertebrates. Based on this phylogeny, a student asks "Does this mean that lizards, frogs, and rabbits all possessed hair and an egg with amnion at some point in their evolution?" Evaluate the phylogeny, then select the most accurate answer to the student's question.

What causes the changes in protein structure through the three or four levels of structure?

The primary chain forms secondary α-helix and β-pleated sheets which fold onto each other forming the tertiary structure.

Describe the change in structure through the 3rd or 4th levels of protein structure.

The primary polypeptide structure is folded into the secondary structure by hydrogen bonds; amino acid side chain interactions then form the tertiary structure. Sometimes multiple subunits come together to form a quaternary structure. These subunits can be the same or different from each other.

Which of the following variables did Pasteur change in his experiment to test the hypothesis of spontaneous generation?

The shape of the flask

Compare the DNA sequences of water lilies and water lotus.

The water lotus (Nelumbo) and the water lilies (Nymphaeaceae) share a similar appearance because they thrive on calm waters. How could a scientist best show that these species are distantly related and evolved their similarities through convergent evolution?

How do the α and β forms of glucose differ?

Their ring structures differ in the location of a hydroxyl group.

How does a scientific theory differ from a scientific hypothesis?

Theories are usually an explanation for a more general phenomenon; hypotheses typically address more specific issues.

What conclusion, if any, can be drawn about leaf mimicry from this study?

There is statistically significantly less leaf damage in the vines on leafy host trees compared to that in vines creeping on the ground or vines on bare tree trunks. This result suggests that growing among other leaves protects the vine from predation by plant eaters.

In Pasteur's experiment to test the hypothesis of spontaneous generation, why did he boil the broth in both flasks?

To kill any existing organisms in the broth

The lancelet branched off first, followed by the shark, then the frog, then the snake and then the ostrich.

Using the data presented, construct the phylogenetic tree for the species represented. Identify where on the tree each feature evolved then select from below the correct description of the evolutionary sequence.

Animalia: Multicellular organismsthat get their energy through ingesting other organisms.

Using the taxonomic classification system, which Kingdom category best describes a bear?

Which example most clearly shows a way that humans can respond directly to a change in the environment?

We shiver when we are cold and sweat when we are hot.

the shared common ancestors

What do phylogenetic relationships refer to?

Computer programs help determine relatedness using DNA sequencing, and morphologic and molecular information is more effective in determining phylogeny.

What effect has the advancement of DNA technology had on determining phylogeny?

Italicize both words. The first word should be capitalized. The second word should be lower case.

What is the correct way to format a two-word scientific name?

Animals, Fungi, and Plants

What is the largest clade in the preceding diagram?

iTOL is an online tool that provides the display and manipulation of pre-computed phylogenetic trees, and you can upload and display your own trees and data.

What is the main function of the ITOL (Interactive Tree of Life) website?