Review Projects – 2013 Big Idea 4 Mr. Bennett

1. Review Projects – 2013 Big Idea 4 Mr. Bennett

2. LO 4.1 Answers • Multiple Choice Question: • DNA polymerase will proofread the new DNA as it is synthesized. However polymerase is not perfect and will not catch every mistake. What other biological process will prevent the mutation (mistake) from affecting the protein that the gene was intended to code for? • a. Redundancy in the anticodons that are specific to each amino acid • b. Splicing of introns and the connection of exons by the splicesome • c. Alternative RNA splicing • Transfer RNA (tRNA) will correct the unseen mutation when transferring amino acids to the ribosomes • Correct Answer: A Learning Log Question Answers • A base pair-substitution is the replacement of one nucleotide and its partner with another pair of nucleotides. Some of these are known as silent mutations because they have no effect on the encoded protein due to redundancy. They may also cause missense mutation where the altered codon still codes for an amino acid they may not necessarily make sense but it will still produce a protein. Substitution can also cause a nonsense mutations where the change in the base pair will cause translation to be terminated prematurely and the resulting polypeptide may be shorter or nonexistent causing the protein to change in structure and function or to not exists at all. • Insertions and deletions are additions or losses of nucleotides pairs in genes. These mutations are known as frame shift mutation whenever the number inserted or deleted is not a multiple of three. This mutation is most likely to produce a protein that is almost certain to be nonfunctional, unless the frame shift is near the very end of the gene.

3. Answer Key- L.O. 4.3 M.C. Question: A protein undergoes a change in which an amino acid containing a sulfhydryl R-group is replaced with an amino acid containing a cationic R-group. Which of the following will likely be a result of this change? The secondary structure of the protein will change from a pleated sheet to a helix. The tertiary structure of the protein will be altered as a result of altered disulfide bridge interactions. The protein will denature at room temperature. The protein’s properties will not change. Both B and C are true. FRQ: A) Describe the structural and functional differences between DNA and RNA. DNA is double stranded and takes the 3-dimensional shape of a double helix. It contains the nitrogenous bases adenine, thymine, cytosine, and guanine and has a backbone composed of phosphate groups and deoxyribose sugars. Its primary function is to store the genetic code. RNA is single stranded, contains the nitrogenous bases adenine, uracil, cytosine, and guanine, and has a backbone composed of phosphate groups and ribose sugars. Its primary function is to carry the genetic code from the nucleus to the ribosome (mRNA) and to assist in transcription from gene to protein (tRNA.) B) List and describe three specific biological examples of protein structure relating to function. Aquaporin: protein channel containing a hydrophilic interior that allows for the passage of water in/out of cells via plasma membranes during osmosis. Hemoglobin (sickle-cell): Sickle-cell anemia is caused by a point mutation in the β-globin chain of hemoglobin, causing the hydrophilic amino acid glutamic acid to be replaced with the hydrophobic amino acid valine at the sixth position, thus altering protein structure and leading to symptoms of sickle-cell such as reduced oxygen transport. Enzymes: specific interactions among amino acids within an enzyme influence the tertiary/quaternary structure of an enzyme, which directly influences shape of the enzyme as a whole, and specifically the shape of an enzyme’s active site and/or allosteric site. Since enzymes work on specific substrates, which bind to specifically-shaped enzyme active sites, a change in amino acid make-up within an enzyme can deactivate the enzymes specificity to substrates.

4. Answer Key LO 4.4 • Arrange the following 5 organelles in an order that shows their involvement in the secretion pathway of a protein in a cell. • 1. Golgi Apparatus • 2. Ribosome • 3. Transport Vesicle • 4. Endoplasmic Reticulum • 5. Secretory Vesicle • 2, 1, 4, 3, 5 • 1, 2, 3, 4, 5 • 2, 4, 3, 1, 5 • 4, 2, 1, 3, 5 • 2, 4, 1, 3, 5 Useful diagram for the learning log question. Tay-Sachs disease is an autosomal recessive genetic disorder that is caused by insufficient activity of hexosaminidase A, a hydrolytic enzyme that breaks down GM2 ganglioside. Discuss the organelles involved in the production of lysosomes. Explain the effects of insufficient enzyme activity on macromolecules like GM2 ganglioside. A Lysosome is a membranous sac that contains hydrolytic enzymes. Both the enzymes and the lysosomal membrane are made by the rough Endoplasmic Reticulum and are then transported to the Golgi apparatus to be processed. The result is a functioning lysosome filled with the necessary enzymes. Typically lysosomes engulf targeted molecules, a process known as phagocytosis, but insufficient enzyme activity is caused by the lysosome being engorged with indigestible substrates, which hinder the lysosomes ability to break down other molecules, and this causes cellular waste to build up inside a cell. For people with Tay-Sachs disease, hexosaminidase A is either not present or inactive, so lysosomes cannot break down GM2 ganglioside and leads to an accumulation of the macromolecule.

5. Answer LO 4.5 Insulin is a protein that is produced by certain pancreatic cells and secreted into the bloodstream. Which of the following choices best describes the route of insulin from its production to its exit from the cell? A) rough ER, transport vesicles, cell membrane B) rough ER, transport vesicles, Golgi apparatus, transport vesicles, cell membrane C) rough ER, lysosomes, transport vesicles, cell membrane D) rough ER, Golgi apparatus, smooth ER, cell membrane E) None of the choices are correct Learning Log Question: During an intense study in the Amazon River, a college Biology student came across a unicellular water organism. Upon further study, the student came to the conclusion that the organism was eukaryotic. Name 4 subcellular structures that would be found in the unicellular organism and tell it’s function in how the structures help keep the cell viable. The nucleus is the genetic housing center of a cell. There is a double membrane surrounding the chromosomes and nucleolus. Pores allow specific communication with the cytoplasm. This is also the site for RNA synthesis, making up the ribosome. Mitochondria are surrounded by a double membrane with a series of folds called cristae. It functions in energy production through metabolism. Mitochondria contain DNA and are believed to be originated from captured bacterium. The Golgi Apparatus is a series of stacked membranes. Vesicles carry materials from the RER to the Golgi. The vesicles move between the stacks and proteins are made into a mature form. Vesicles carry newly made membranes and synthesized proteins to their destination (this includes secretion and membrane localization. The cell membrane functions as a barrier that makes it possible for the cytoplasm to maintain a different composition from the material surrounding the cell. The unit membrane is freely permeable to water molecules but very impermeable to ions and charged molecules. It contains various pumps and channels made of specific transverse membrane proteins that allow concentration gradients to be maintained between the inside and outside of the cell.

6. ANSWER KEY- LO 4.6 • Which would result if ribosomes stopped working within a cell? • Proteins would be anchored into the ER membrane by their hydrophobic tails. • Enzymes would be able to catalyze the first steps of sugar breakdown. • Glycoproteins would not be passed through the ER and Golgi. • The nucleolus would not exist within the nucleus. In eukaryotic cells, organelles work together to accomplish specific tasks and make the cell function. Explain how certain organelles work together to produce proteins within the cell. Draw a model to represent the different steps and organelles involved in protein production. (sample drawing) The nucleus, ribosomes, rough endoplasmic reticulum, and the golgi apparatus work together to produce proteins. First, the nucleus synthesizes ribosomal RNA in the nucleolus. The ribosomal RNA is synthesized from instructions in the DNA located in the nucleus. The mRNA then exits to the cytoplasm through nuclear pores. Once in the cytoplasm, ribosomes on the rough endoplasmic reticulum translate the mRNA into amino acid sequences and a polypeptide chain grows. As the polypeptide chain grows it is threaded in the ER, folds into a certain shape, and is put into the ER membrane by their hydrophobic tails. When ready, the molecule is taken to the golgi apparatus via transport vesicles. Here the transport vesicle fuse with a golgi membrane and is then sent through the golgi to be modified if needed. When the vesicle reaches the other side of the golgi, the protein is released to the surface of specific organelles or the plasma membrane.

7. LO 4.7 Answers • M.C. Question: D, a homeotic mutation would not help in the formation of an organism’s development of the eye, instead, it might hinder the eye’s development or even replace the eye with another structure. • FRQ Question: Failure of an induction signal to reach the anchor cell for a vulva would stop the entire formation process of the vulva altogether. Without the signal’s reception, a message to create a transcription factor that would help in determining the cell’s type never arises, and the cell will not take on any specialization because the products that the transcription factor’s specific gene activation will never appear in the cell, so the cell will never be able to achieve the characteristics of the desired cell type, nor will it be able to send other precursor cells signal proteins to help them to form the vulva.

8. Jerking your hand quickly away from a hot stove is an involuntary response that occurs to help one evade major injury. What types of systems work together to create this type of survival response, and which components, specifically, create this response? A) respiratory and circulatory systems—pharynx, trachea, and heart B) stomach and small intestines—esophagus and gallbladder C) nervous system and muscles—optic nerve and cerebral cortexD)nervous system and muscles—sensory neurons, interneurons in spinal chord, brain, interneurons, motor neurons to muscles in hand ANSWER KEY—LO 4.8 Plants, such as the vascular plant shown to the right, are comprised of different parts which work together to allow them to survive appropriately. Describe how the different parts of the plant, particularly the roots, stem, and leaves, work to carry out the processes of the plant (such as photosynthesis or transpiration) which enables it to survive. (Transpiration) Water, along with nutrients contained within the soil, enters the plant through diffusion, through the root hairs, which are extensions of epidermal cells. The roots contain a cortex made of cells that contain plastids for the storage of starch and other organic substances. Water then moves from the cortex to the endodermis, encircled by the Casparian strip, which controls water entering the plant. Next, the water can pass into the vascular cylinder and also the xylem, where it can move towards the top with the help of forces such as tension and transpiration pull. Water also diffuses to the air spaces of the leaves, and from the veins of the leaves, water moves to the mesophyll cells, which are used in photosynthesis. During the process of photosynthesis, oxygen and water vapor is produced and released into the atmosphere when the stomata on the bottom of the leaves open.

9. Answer LO 4.9 Multiple Choice Question: The prairie vole is one of the few monogamous mammal species in the world. During sex of the prairie voles, the hormone oxytocin is released by the pituitary gland; oxytocin is associated with establishing social bonds and pleasure. What would most likely occur if a vole was born without functional oxytocin receptors due to a mutation? A) No change would occur. B) The prairie vole would not demonstrate monogamous behaviors. C) The vole would not have sex because there is no reward for the behavior. D) The vole would be in capable of feeling pleasure in general. E) Both B and C. FRQ-style Question: What would be the effect if a substance that counteracts CD8 on T cells is introduced? What about a substance that counteracts CD4? Include the functions of CD4 and CD8. During the immune response, the antigen presenting cell is closely bound to helper T cells by CD4 during gene rearrangement; this stimulates the helper T cell to produce cytokines, which in turn stimulate cytotoxic T cells. The cytotoxic T cells also must undergo gene rearrangement; however, rather than CD4 keeping the infected cell bound to the T cell, CD8 does this job for cytotoxic T cells. Therefore without CD8, the cytotoxic T cells would not undergo gene rearrangement and would not be able to kill infected cells through granzyme and perforin induced apoptosis; the immune response would be incomplete. Similarly, the helper T cells would not be able to undergo gene rearrangement without CD4; however, this would prevent the cytotoxic T cells and B cells from being stimulated causing a complete failure of the immune response; antibodies would not be produced to combat the antigen and apoptosis of the target cells would not occur. True love…

10. ANSWER KEY– LO 4.10 In which of the following is not dependent on interactions between the roots, stems, and leaves? A) Reproduction B) Transport C) Photosynthesis D) None of the above Organisms are made to be complex through the interactions between different parts within the body. Explain how the knee-jerk response displays this complexity . In the knee-jerk response the nervous system works with the muscle system in order to create the forward thrust of the lower leg. The tapping right below the knee cap initiates the tendon that causes a stretch in the quadriceps which is detected by sensors releasing neurons. These neurons send signals telling the quadriceps to contract and the hamstring to not contract. The result is a forward jerk of the lower leg. The communication between the neurons sent out and the muscles contracting constitute a interaction between the nervous system and the muscle system.

11. LO 4.11: The student is able to justify the selection of the kind of data needed to answer scientific questions about the interaction of populations within communities. SP 1.4: The student can use representations and models to analyze situation or solve problems qualitatively and quantitatively. SP 4.1: The student can justify the selection of the kind of data needed to answer a particular scientific question. M.C Question: Based off the data given below which set of information about the population in the community is both quantitative and qualitative? A) There was about two hundred animals in the population, and they had very aggressive behavior towards each other. The animals were mostly brown with a few black ones. They ate about four times a day. B)With only two hundred animals in the population it seemed very small compared to others. They ate four times a day. They only slept for three hours a day because other time they were on the hunt. They were about 5 feet long. C)They were very aggressive towards each other. They all were mostly brown with a few black ones. D) All the above Learning Log/FRQ-style Questions: Suppose you are collecting data of a species in a population and you learned that they are often referred to has a keystone species. What would happen if they disappeared? How would that impact the other species in the population? And what kind of data could you use to show the down falls in the population? Answer: Keystone species have a impact on a population and help regulate there cycle. If they disappeared a lot of things could happen. They feed on and help regulate the population of other species in the population that may otherwise cause damage if population were to grow unchecked. They could help promote primary productivity by helping to ensure the reproduction of a variety in plants and other things because they are pollinators which wouldn’t happen if they were gone. Loss of them could lead to population crash and extinction of other important species in the population through reduction of competition or other factors. The also could be how key nutrients gets to different ecosystems. All species are connected in some way and play a role in the population weather its the predator, prey, or anything else, they all need each other to keep the cycle going. If you truly wanted to find out the result of this you could make a population with a keystone species missing from the population and see how it different from the real life one in the wild. You could use a chart to record the data for each set up with quantitative and qualitative information. Food chains are a good way to show how a population is made up of the interaction between animals. It can answer many questions about what would happen if something went missing like a certain species, or if we were missing grass. Each one leads to another, creating a interaction between each other.

12. LO 4.12 • Answer to M.C: 0.05(500)(500/1000)= 12.5 • Answer to L.L: A population may not be able to grow exponentially if the population lacks enough mates and therefore competition for mates would increase. Also predation could play a role where the certain species might be near the bottom of the food chain and lack the skills of camouflage. Populations might exceed the carrying capacity but then come back down if an natural disaster occurs that causes the lose of habitat which would kill off some of the species.

13. Answer Key: LO 4.13 MC: B—At this point, the population of rabbits has declined to the point where the foxes are starting to feel the reduction in their food supply. The fox survival curve soon begins its decline that leads to the revival of the rabbits. LL/FRQ According to the trophic cascade model, the top predators of an ecosystem affect the nutrient content in a community. If all top predators are removed from a community, what would need to change within the community’s population so that it remains sustainable? The mesopredators of an ecosystem would increase in population sizes. That is, the intermediate predators begin to play greater roles within a community, as with top predators present harsh competition to mesopredators that are suppressed when top predators roam about. These species fulfill the role of keeping the lower trophic level populations in check, especially the primary consumers and, subsequently, the producers of a community. This is referred to as the mesopredator phenomenon, exemplified by the loss of large sharks in the ocean, causing the populations of smaller-bodied sharks and rays to increase. However, the mesopredator release causes the mesopredator’s prey populations to decrease dramatically, so true sufficiency is not achieved once the top predator is taken out of the equation entirely.

14. ANSWER KEY– LO 4.15 • The flow of energy in an ecosystem disperses through a simple food chain from grasses to grasshoppers to chickens to foxes. Based on this information which of the following statements is true? • Foxes likely contain the highest concentrations of fat-soluble toxins. • More energy can be obtained from chickens than grasses. • Grasshoppers are most likely to be affected by low levels fat-soluble pesticides sprayed on the mosses. • Grasses provide the lowest nutrient levels. • Ten percent of energy from the sun is converted to chemical energy by grasses. • A population of cows and bears live in the same area. The cows feed on local plants and grasses while the bears consume some of the cows as well as vegetation. Despite a wider availability of food sources for the bear, there is more energy available to a cow than a bear. Why might this be? Provide an illustration to support your answer. • Energy is more readily available at lower trophic levels. From one trophic level to the next only about ten percent of energy is transferred. This is due to the fact that organisms use much of the energy they obtain for life processes, such as respiration, movement, and reproduction. Producers harness energy from the sun and convert it into chemical energy which can be obtained by the cow and the bear. However, the bear also obtains energy from consuming cows provide less available energy as they are primary consumers rather than producers. Cows provide approximately ten percent less energy than the vegetation which exists at a lower trophic level. Thus as the bear consumes food at higher trophic levels, they have less energy available to them than the cow who solely consumes at the lowest trophic level it can, providing it with the most energy possible. • (Possible supporting illustration)

15. ANSWER KEY– LO 4.16 M.C. Question: A million J of sunlight is usually available in North Carolina each day. After a meteor strikes, 50% of the sun's energy can no longer reach the ground. Assuming that no organisms enter or leave the environment how many J of energy are available to the hawk each day?A) 50,000J B) 5,000 J C) 500 J D) 50 J    E) 5 J  Learning Log/FRQ-style Question: A coal-fired power plant opens and is surrounded by a large forest. The air becomes polluted and coal dust covers a large portion of the forests. Predict the change in energy availability in the ecosystem and how that change will affect the communities that are located in the forest. Which species will be affected the most? Why? Would an opposite change in energy have an inverse affect? The amount of energy available in the ecosystem would decrease. Because the photoautotrophs would be unable to have as much photosynthetic activity, energy from the sun would not enter the food chain as abundantly. This means that at each subsequent trophic level, progressively less energy will be available. In a forest ecosystem, the upper trophic level consumers (birds of prey such as hawks and omnivores such as bears) will be the most likely to change drastically because of this change. Because a huge number of producers and lower trophic level consumers support just a few of these upper level organisms, a small change in the lower level can lead to starvation and death at the higher levels. If their was to be an increase in available energy, such as a clearing of the ash from the air, then the producers would thrive and allow for all the subsequent trophic levels to increase in number.

16. Answer Key- L.O. 4.17 M.C. Question: How does a noncompetitive inhibitor decrease the rate of an enzyme-mediated reaction? By changing the shape of a reactant By changing the free energy dynamics of the reactions By acting as a coenzyme of the reactions By decreasing the activation energy of the reactions By binding at the active site of the enzyme FRQ: Graph the data and calculate the rate from 0 to 30 minutes. Rate – 0.35 mM/min b) Explain why a change in rxn rate was observed after 30 minutes. The reaction rate slows/levels off because the substrate is used up, therefore decreasing the substrate concentration. c) Draw and label another line on the graph to predict the results if the concentration of amylase was doubled. Explain. The line will mimic the original data line, but will be higher, leveling off at a higher point. More enzyme = more product (maltose) formed over time, but product will level off as substrate concentration decreases. d) Identify TWO environmental factors that can change the rate of an enzyme-mediated reaction. Discuss how each of those two factors would affect the reaction rate of an enzyme. Temperature increase will cause an increase in reaction rate due to faster molecule movement (kinetics.) However, if temperature increases past a certain point, reaction rate will slow/stop due to the enzyme becoming denatured. Denaturation results from bonds holding together the tertiary structure of the enzyme breaking, which leads to altered enzyme/active site shape. Also, a change in pH away from the optimal pH for the enzyme will slow reaction rates.

17. LO 4.18 AnswersMC QUESTION: Which of the following is NOT true about organs concerning organisms and organ systems.A. Organ systems are a key evolutionary trait regarding the survival of organisms. B. Organs are always contained inside of an organism (skin) C. Organs can compensate for the malfunction of another organ within an organism. D. Some organs have regenerative abilities if they are damaged. Explain how the human digestive system effectively breaks down and uses matter. Each part of the human digestive system is important in the effective use of matter. Initially matter is broken down manually by the mouth as well as chemically by saliva. Then it goes to the stomach and is broken down chemically further. As the food continues to pass it is broken down by enzymes created by the pancreas. The liver produces bile which aids in the breakdown of fat. Food then travels to the small intestine where it is absorbed through the lining of the wall. After the nutrients are absorbed the material passes to the large intestine where water is absorbed and the material is packed. Then the material is excreted as waste.

18. LO 4.19 Answer Key Multiple Choice Question Answer: According to the graph on the right, which of the following statements is true? A: A spike in the number of snowshoe hare leads to an increase in the number of Canadian lynx. B: The Canadian lynx act as parasites upon the snowshoe hares. C: The maximum and minimum populations of snowshoe hare and Canadian lynx do not occur at the same time due to a time lag in which both species respond to the population of the other. D: Both A and C are true. FRQ Answer: Because Kudzu is a Japanese vine, it is an invasive or exotic species that did not originate in North America. The land and plants in North America are not adapted to the effects of Kudzu, allowing its rampant growth and destruction of any vegetation that crosses its path. The relationship between Kudzu and the surrounding plants is one of parasitism. Kudzu uses the plants it takes over as nutrition, and the plants simply die due to the all-encompassing Kudzu’s power to take over their water and sunlight. Therefore, the Kudzu species would flourish, and the native plant populations would possibly dwindle to extinction over many years of Kudzu’s damaging effects. The relationship between Oxpecker birds and hippopotamuses would be one of mutualism because in a mutualistic relationship, both species benefit from the actions of the other; the hippopotamus is gaining hygiene and cleanliness, while the Oxpecker bird is gaining food and nutrition. An increase of birds means more healthy hippopotamuses that can reproduce and create more hippopotamuses, thereby increasing the need of Oxpeckers to clean more hippopotamuses. Generally, as the amount of hippopotamuses increases, the number of Oxpeckers increases as well, and vice versa due to their mutualistic relationship.

19. LO 4.20 Answer Multiple Choice Answer: (E) All of the above Each one of those natural disasters would cause a good amount of destruction to the area and would create a great environment for secondary successors to come into play. Free Response Answer: If an area that is accustomed to disaster experiences an extended amount of time without a disaster the diversity of the area will decrease. The plant life in the area depends on the disasters to allow secondary successors to come into play and give the area more diversity. And with no new plant life then there are no new organisms that will inhabit the area.

20. Answer Key-LO 4.21. • M.C. Choice: Climate change, caused by humans burning fossil fuels, can have which effect within one fifty years? • A) Irreversible large scale abrupt changes transitions in climate. • B) Mass extinction across the entire globe. • C) Risks to specialized species • D) no effect. • FRQ: The introduction of invasive species, often from human influence, leads to the threatening of native animals and plants. Explain one reason of each: why invasive species are successful, how invasive species affect their environment, and how they can be eradicated. • Invasive species are given the upper hand in their new environment. The have no natural predators, parasites, or pathogens that would hold them back from uncontrollable growth. These invasive species affect their environment by decreasing biodiversity through out competing native species. Eliminating the food source of an invasive species would lead to their eradication.

21. Answer Key- LO 4.22 All of the following are true about the Humoral response except: A. The helper T cell allows the B cell to proliferate. B. Antibodies are only produced through B cells. C. The antibodies produced are similar in inactivating antigens. D. The five classes of antibodies are different in structure. E. During proliferation, both plasma cells and memory B cells are cloned. The Helper T cell is a key part of the human immune system. Identify and explain the Helper T cell’s role in allowing the body to defend itself from antigens The Helper T cell plays a very important role in the processes of the immune system, both in the cytotoxic T cells and the Humoral response. The Helper T cell becomes activated by an interaction with a macrophage that contains peptide antigens and displays a particular MHC molecule (either Class II for Humoral response or Class I for cytotoxic T cells). Once the helper T cell is activated, it releases a group of proteins called the cytokines that activate the cytotoxic T cell or the B cell. The Cytotoxic T cell will destroy a target cell through the release of perforin and granzymes, which will lyse the target cell. B cells (humoral response) will become directly activated by the Helper T cell and will begin to proliferate or clone. Proliferation will produce both memory B cells, which will allow a humoral response for the antigen in the future, and plasma cells that contain antibodies that will inactivate the target cell.

22. ANSWER KEY– LO 4.23 M.C. Question: Which of the following is not an example of an environmental factor that will affect the phenotype of the organism? A)The amount of Nitrogen affects the leafiness of a plant by helping the plant make protein to stay healthy, and as the nitrogen levels increase the rate of leaf growth will also increase. B)Sunlight changes the color of a human’s skin by cell receptors on the skin that take in sunlight and form more Melanin. C) The amount of nitrogen that is taken in by humans will affect growth. D) The change in leaf size in a species of plants based on how much light they developed under. Create an experimental design to explain how you would test to see how an environmental factor could affect an organism’s phenotype. You could gather multiple organisms of the same species and same genotype. Then you would isolate each organism in the same environment, but you would change one of the factors of that environment, and then you’d record your findings. One of the organisms would have to be the control, and would be in a completely normal environment. The independent variable would be what you are changing in the environment, and the dependent variable would be the organism that is being affected.

23. Multiple Choice and Free Response Solutions • LO 4.24 Answers • The correct answer is B. Since virtually everything on the island is covered in black ash, the black-colored moths will blend in with their environment. This camouflage helps them to avoid predators, while the white moths will be preyed upon more frequently, due to the fact that they are easier to see in their dark-colored environment. Thus, due to natural selection, the frequency of the recessive allele will increase. The moths with that allele are far more likely to survive and pass on their genes to their offspring, so the frequency of the black-colored moths (and, consequently, the recessive allele) will trend upward. • Since water has a very high heat of vaporization, jackrabbits need large ears to survive in their desert environment, as their large surface area allow for the evaporation of water to take place. This allows heat to escape from the bodies of the jackrabbits and cools them. An increase in the temperature of the room, therefore, will necessitate a larger evaporative cooling, in order for the jackrabbits to maintain healthy body temperatures. Thus, the frequency of the dominant allele will decrease, and the frequency of the recessive allele will increase. • For the same reasons stated above regarding evaporative cooling, there will be an increase in jackrabbits with larger ears and a decrease in jackrabbits with smaller ears. This is because the ones with smaller ears will not be able to cool themselves off as much as those with larger ears will after the temperature increase. • The Darwinian process of natural selection indicates that because the jackrabbits with smaller ears will not be able to cool themselves very well after the temperature increases, they are far less likely to survive and pass their genes on to their offspring. The jackrabbits with larger ears, however, have a much greater chance of doing this. This leads to a proliferation in the number of large-eared jackrabbits and, consequently, the recessive allele.

24. LO 4.25 AnswersMultiple choice: C • A) Grazers that can subsist on coarser diets of desert scrub. Grazers that also eat some insects and possibly reptiles. Grazers that are active more at night to conserve energy and water. Grazers that absorb all water from their meal instead of passing some through digestion. • B) Beetles that can burrow during the day. Beetles that absorb all moisture from their food. Beetles that are better at hunting small reptiles and insects that are more abundant in the desert. • C) Grass with narrow leaves for less transpiration. Grass with longer roots. Grass with a thicker cuticle. Grass that only open the majority of its stoma at night.

25. LO 4.26 Answer Key M.C. Question: Genetic diversity is the a) Sum of the total genetic information contained in genes of individuals of a species b) Sum of the total genes in an individual c) Sum of the total chromosomes in an individual d) Sum of the total chromosomes present in the individuals of a species FRQ/Free Response Question: What role does genetic diversity play in the survival of a species? Genetic diversity plays an important role in the survival and adaptability of a species. When a populations habitat changes, the population may have to adapt to survive; "the ability of populations to cope with this environmental challenge depends on their capacity to adapt to their changing environment.” Variation in the populations gene pool provides variable traits among the individuals of that population. These variable traits can be selected for, via natural selection; ultimately leading to an adaptive change in the population, allowing it to survive in the changed environment. If a population of a species has a very diverse gene pool then there will be more variability in the traits of individuals of that population and consequently more traits for natural selection to act upon to select the individuals to survive. High genetic diversity is also essential for a species to evolve. Species that have less genetic variation are at a greater risk. With very little gene variation within the species, healthy reproduction becomes increasingly difficult, and offspring are more likely to deal with problems such as inbreeding. The vulnerability of a population to certain types of diseases can also increase with reduction in genetic diversity.

26. ANSWER KEY- LO 4.27 M.C. Question: Which species’ removal would have the most lasting impact on the ecosystem? Why? The sea otter is a keystone species, so its removal from an ecosystem would affect the ecosystem more than the removal of a non-keystone species. Keystone species have impacts that are much larger than what would be expected from their relative biomass. The other answer choices may have large impacts on their ecosystem, but they are not larger than what is expected due to their biomass and they are not keystone species. Fungi Sea otter Prairie grass Minnow Learning Log/FRQ-style Question: a) Describe the two components of species diversity. b) Explain how species diversity affects an ecosystem’s stability. c) Referring to the figure, which community is more prepared for a disaster? Why? • (1) Species richness is the number of species in the community. (2) Relative abundance is the proportions of the community represented by the various species. • More species diversity in an ecosystem causes more stability. Diverse ecosystems are more resistant to environmental changes. If an ecosystem is not diverse and a species is not suited for life in that environment, it can be selected against through natural selection and cannot survive and reproduce. Then, there will be no other species to fill the niche that the now extinct species used to fill. Also, more diversity means that more niches are filled, more relationships are formed, and the ecosystem is more productive and successful. • Community 1 would be more prepared for a disaster. Though the two communities have the same number of species, they differ in species diversity and therefore stability because Community 1 has a more diverse relative abundance, a more even distribution of species.