Name: Date: Period: Unit 1 (Evolution) Exam Review ANSWER KEY AP Biology, Topic #1: Evolution Basics & Types of Natural Selection

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1 Name: Date: Period: Unit 1 (Evolution) Exam Review ANSWER KEY AP Biology, Topic #1: Evolution Basics & Types of Natural Selection 1. Centuries ago, the human appendix may have been used to digest raw meat that had not been cleaned properly. Now, the human appendix has lost its ability to function. Explain why this has occurred, using the term natural selection in your response. Over time, people began to cook their meat (leading to the non-use of the appendix). Someone was born with a mutation that caused their appendix to lose its functionality. Because this was advantageous natural selection occurred and these people were more likely to survive because they were not expending energy on using their appendix. Over time this loss of appendix functionality has increased among the population. 2. Lynx (i.e. large cats) have evolved strong sprinting muscles to catch hares (i.e. rabbits). How might the hares evolve in response to this change in the lynx? There is variation already among the hares in how fast they are able to run (or burry underground, or some other mechanism to escape). The hares that have the ability to escape the lynx because of these traits will survive longer and reproduce creating a next generation that is quicker, buries better, etc. 3. Suppose there was a fossilized canine species that possessed traits of ancient wolves and modern domestic dogs. What would this fossil be called, and how does it provide evidence for evolution? This would be a transitional fossil and it helps to show how one species evolved from another by showing an organism that has traits of both the ancient form and the modern form of the organism. 4. Why do scientists look at DNA or amino acid (i.e. the building blocks of proteins) sequences when investigating the evolutionary history of several species? Organisms that are more closely related have more DNA and amino acids in common with one another. There are even conserved traits which are the most important which are common among many different organisms. 5. Suppose a population of daisies ranges in height from short to tall. Over time, the environment becomes much windier and the tall flowers blow over and die. How will the population evolve over the next few generations? Use the terms natural selection, fitness, survival, and reproduction in your response. Over time natural selection will occur (directional selection). There must be variation in the population to begin with in stem length. Because the tall flowers die, the shorter stem flowers will have a higher chance of survival. They will live longer and be able to reproduce more daisies that also have shorter stem lengths. These daises with shorter stem length will have a higher fitness than those with the longer stems. 6. Let s say a population of elephants has trunks ranging in length from short to medium-length to long. Describe a change in the environment that may result in disruptive selection, and describe the changes that would occur in the trunk length frequencies in the population over time. (could be many different answers). The water sources for the elephants were either very close to the ground where the short trunks could reach, or up tall in the trees where the long trunked elephants could reach. Over time these two extremes would be better suited for the environment and would pass on their gene to their children. Following many generations, the new population would have an increase in short and long trunked elephants and a decrease in medium trunked elephants.

7. Let s say a population of elephants has trunks ranging in length from short to medium-length to long.

(could be many different answers). The location of the wheat that they ate (in a bowl) was perfectly suited for medium trunked elephants.

Over time the medium trunked elephants would be better suited for the environment and would pass on their gene to their children.

2 7. Let s say a population of elephants has trunks ranging in length from short to medium-length to long. Describe a change in the environment that may result in stabilizing selection, and describe the changes that would occur in the trunk length frequencies in the population over time. (could be many different answers). The location of the wheat that they ate (in a bowl) was perfectly suited for medium trunked elephants. The short trunked elephants couldn t reach far enough into the bucket and the long trunked elephants were too big to fit in the bucket. Over time the medium trunked elephants would be better suited for the environment and would pass on their gene to their children. Following many generations, the new population would have a decrease in short and long trunked elephants and an increase in medium trunked elephants. 8. Let s say a population of elephants has trunks ranging in length from short to medium-length to long. Describe a change in the environment that may result in directional selection, and describe the changes that would occur in the trunk length frequencies in the population over time. (could be many different answers). The elephants food supply became limited to the items they could find in the tops of trees. Only the long trunked elephants could reach this food supply. Over time they long trunked elephants would be better suited for the environment and would reproduce and pass on their genes. Following many generations, the new population would have an increase in medium-long trunked elephants and a decrease in short trunked elephants. 9. Explain how sexual dimorphism is caused by sexual selection. Provide an example in a population of animals. (Note: Your example can be imaginary or real!) Females are able to choose their mates with the best traits, because of this the traits on the males become more exaggerated than on the female. This causes the male and the female to look different from one another. Examples: gorillas, fiddler crab, cardinals, peacocks/peahens etc. 10. Male elk use their antlers to spar with one another in order to compete for females. Over time, the average male elk antler length has increased. However, at a certain length, long antlers make elk more likely to be caught and killed by wolves. Explain how sexual selection and natural selection have balanced one another in the evolution of elk antler length. Sexual selection has selected for longer antler length; however these elk still need to be able to live until reproductive age. Therefore, the antlers are as long as they can be without interfering with the elk s reproductive ability. Topic #2: Genetic Variation & Hardy-Weinberg Equilibrium 11. Why is sexual reproduction more beneficial than asexual reproduction when it comes to genetic variation and ensuring the survival of a species? Remember, sexual reproduction involves two parents and results in offspring that are not identical to one another or the parents. Asexual reproduction involves one parent and results in offspring that are identical to one another and the parent. Species need to have a large amount of genetic variation in order to survive. When there is low genetic variation, a disease is more likely to spread and cause extinction. Sexual reproduction allows for many more modes of creating genetic variation (crossing over, independent assortment and random fertilization) that cannot occur during asexual reproduction. 12. What process is shown in the picture to the right? When does this occur, and does it increase or decrease genetic variation in a population? This is a mutation that usually occurs during DNA replication during Interphase of the cell cycle. This increases genetic variation by introducing new alleles into a population. 13. What process is shown in the picture to the right? When does this occur, and does it increase or decrease genetic variation in a population? This is crossing over and it occurs during Meiosis (Prophase I and Metaphase I). This increases genetic variation in a population by exchanging genetic information on homologous chromosomes. 14. What process is shown in the picture to the right? When does this occur, and does it increase or decrease genetic variation in a population? This is independent assortment which also occurs during Meiosis. It increases genetic variation by increasing the different combination of chromosomes that can occur.

3 15. What happens during fertilization? Why do we consider fertilization to be random in humans? What does the term random indicate? Does this process increase or decrease genetic variation in humans? Fertilization is when the egg and sperm come together. This is random in humans because any sperms can come together with any egg to make a child. This increases genetic variation because there are countless numbers of combinations that can be made. 16. List and describe each of the five conditions that a population must meet to be in Hardy-Weinberg Equilibrium (i.e. a population that is not evolving with no changes in allele frequencies across generation). Hint: These five conditions are the opposite of the five factors that can cause evolution. 1. No Genetic Drift There should be a large population with no natural disaster events occuring 2. No Gene Flow there can be no immigration and no emigration in a population 3. No Mutations no new alleles can be introduced 4. No Sexual Selection mating must be random 5. No Natural Selection there must be no natural selective pressures in the environment. 17. In Drosophila (fruit fly), the allele for normal wing length is dominant over the allele for short wings. In a population of 1000 individuals, 360 show the recessive phenotype. How many individuals would you expect to be homozygous dominant for the trait if the population is in Hardy Weinberg Equilibrium? q 2 = 360/1000=.36 q =.6 p=1-q =.4 p 2 = The allele for a widow's peak (hairline) is dominant over the allele for a straight hairline. In a population of 500 individuals, 9% show the recessive phenotype. How many individuals would you expect to be heterozygous for the trait if the population is in Hardy Weinberg Equilibrium? q 2 =.09 q=.3 p=.7 2pq= x 500 = The ability to taste PTC is due to a single dominate allele "T". You sampled 215 individuals in biology, and determined that 150 could detect the bitter taste of PTC and 65 could not. Determine the frequency of the dominant allele in this sample of students if the sample is in Hardy Weinberg Equilibrium? q 2 = 65/215 =.30 q =.55 p =.45 Topic #3: Macroevolution and the History of Life 20. Describe the difference between prezygotic and postzygotic barriers to reproduction between two populations. Prezygotic barriers occur before the egg and sperm meet whereas postzygotic barriers allow the egg and sperm to meet but the offspring or grand-offspring are not fertile or viable. 21. Provide an example of a prezygotic barrier. Behavioral, temporal, mechanical, habitat, or gametic isolation. 22. Provide an example of a postzygotic barrier. Reduced Hybrid fertility, Reduced Hybrid viability, Hybrid breakdown 23. Two populations of bacteria were raised on two different food sources glucose (Population #1) and lactose (Population #2). Each population adapted to its food source. When members of the two populations were put in the same petri dish, scientists recorded the number of successful matings within and between members of the two populations. Female Male Population 1 Population 2 Population Population

population. This might tell you that they are still the same species but eventually they could evolve into two separate species. 24.

4 (23 continued) Are the populations two different species? How do you know? They are two different sub-species > the data shows much higher successful mating between members of a similar populations; however there are still successful matings between members of the opposite population. This might tell you that they are still the same species but eventually they could evolve into two separate species. 24. If two populations of giraffe can mate and produce living offspring but the offspring are sterile (i.e. infertile or unable to reproduce), are the two populations members of the same species? Why or why not? Not the same species because in order to be of the same species, the populations must be able to produce fertile, viable offspring, but this example shows a post-zygotic barrier (reduced hybrid fertility) and therefore proves that these two populations are not of the same species. 25. Identify the model for the rate of evolution gradualism vs. punctuated equilibrium shown by each graph to the right. Explain your choices. Top = gradualism shows slow change over time Bottom= punctuated equilibrium periods of no change punctuated with periods of fast change 26. Several populations of the same ancestral species of river turtle spread out to different rivers and adapted to each new environment. Over time, the members of the different population became unable to mate successfully with one another. Is this an example of divergent evolution, convergent evolution, or coevolution? Explain your answer. Divergent evolution common ancestor, but new traits due to a change in the environment. 27. Lizards and salamanders are not closely related. Lizards descend from ancestral reptiles, and salamanders descend from ancestral amphibians. Because they live in similar environments, however they have adapted similar body forms (ex: four limbs and a tail). Is this an example of divergent evolution, convergent evolution, or coevolution? Explain your answer. Convergent evolution these organisms do not share a common ancestor but have evolved similar traits due to similarities in their environment. 28. The old world swallowtail (Papilio machaon) caterpillar lives on the fringed rue (Ruta chalepensis) plant. The rue produces oils that repel plant-eating insects. The old world swallowtail caterpillar developed resistance to these poisonous substances. Is this an example of divergent evolution, convergent evolution, or coevolution? Explain your answer. Co-evolution the two organisms have evolved in response to one another. 29. The image to the right shows Miller and Urey s apparatus for their origin of life experiment. A) What did the gases in the large round chamber represent? The makeup of Early Earth s Atmosphere B) What did the electrical spark represent? The Lightning C) What did Miller and Urey find using the sampling probe in the cooled water at the bottom of the apparatus? What conclusion did they draw from their results? Amino Acids that the conditions of early earth could produce the monomers needed to create macromolecules.

How does this relate to the origin of eukaryotic cells? Which cell part chloroplast or mitochondrion appears to have evolved first, and how do you know?

5 30. Which molecule DNA or RNA have scientists concluded was the first molecule of inheritance? How did they conclude this? RNA it has the ability to self-replicate (catalytic properties) and also store genetic information 31. What process is shown in the picture below? How does this relate to the origin of eukaryotic cells? Which cell part chloroplast or mitochondrion appears to have evolved first, and how do you know? Endosymbiotic theory the idea that eukaryotic organisms were created through one cell ingesting another cell. According to this image it appears the mitochondria appeared first and then only in some cells did chloroplasts evolve. HOWEVER, mitochondria use oxygen in the atmosphere to break down glucose and convert it into energy. There was no oxygen present in the early atmosphere, so it would seem that chloroplasts must have evolved first to produce oxygen and allow it to build up in the atmosphere before aerobic cellular respiration in mitochondria was necessary. 32. What are two features of mitochondria and chloroplasts that suggest they were once free-living prokaryotic cells? Have their own DNA (circular) Ribosomes Double Membrane Replicate by fission (like prokaryotes) Same size and shape of prokaryotes 33. Identify 3-5 major steps in the history of life that led from the synthesis of the first simple organic molecules (ex: amino acids) to the origin of the first multicellular organisms with cells specialized for particular functions? 1. First cells = protocells (no nucleus or organelles) billion years ago (bya) = oxygen accumulates in Earth s early atmosphere due to photosynthesis in bacteria bya = eukaryotic cells appeared as a result of endosymbiosis bya = multicellular eukaryotes appear with specialized cells to perform a particular function for the organism (ex: our red blood cells carry oxygen through our bodies) million years ago = colonization of land with plants, fungi, and animals appeared; up until this point, most life (both unicellular and multicellular) was aquatic (water-dwelling) Topic #4: Classification and Biodiversity 34. On the phylogenetic tree shown to the right, what happened to species W? Species W went extinct approximately 10 mya 35. On the phylogenetic tree shown to the right, among species X,Y, and Z, which two species share the most recent common ancestor? How do you know? Species Y and Z share a more recent common ancesoty (10 mya) although all three do share a common ancestor about 15 mya. This can be seen because they branch off at a later time compared to the other organisms. 36. Describe three traits found in the universal common ancestor of the three domains of life Archaea, Bacteria, and Eukarya. (Note: These traits are also found in current members of the three domains of life.) A common genetic code based on DNA Common processes (replication) and molecules (enzymes) used to create a copy of DNA for new cells Common processes (transcription and translation) and molecules (enzymes) used to create proteins from the code in DNA using 20 different protein building blocks called amino acids A common energy storage molecule called ATP and common processes of creating this molecule (cellular respiration) Common cellular features (ex: a watery fluid called the cytoplasm surrounded by a membrane made of lipid / fat molecules

37. Use the table of shared morphological characteristics for the four species Spermocyon, Castropsis, Pseudofelis, and Neomysticena to create a cladogram in the space below showing the evolutionary

6 37. Use the table of shared morphological characteristics for the four species Spermocyon, Castropsis, Pseudofelis, and Neomysticena to create a cladogram in the space below showing the evolutionary relationships for these four species. Your cladogram should include tick marks to represent the traits. Character Spermocyon Castropsis Pseudofelis Neomysticena 3 toes on hindfeet X X X Naked tail (hairless) X X X X Incisors greatly enlarged X X Hair tufts protrude from ears X Pseudofelis Spermocyon Castopsis Neomysticena Hair tufts protrude from ears Incisors greatly enlarged 3 toes on hindfeet Naked tail (hairless) Statistics: Error Bar Graphing 38. What is the formula we use to calculate our range for a 95% Confidence Interval? 95% Confidence Interval = mean ± 2SEM 39. Use the following data to make an error bar graph, with the error bars representing the 95% confidence interval. Average Number of Sodium Ions That Can Enter A Nerve Cell Normal Nerve Cell Nerve Cell Treated with Poison Mean (x ) Standard Error (SEx ) I will have this graph completed to look over tomorrow in class! 40. Do the errors bars overlap? What does that mean? What does it mean if the opposite happens? The error bars do not overlap, which means that the difference between the two means is most likely statistically significant. This means that treating a cell with poisonactually does make a statistically significant difference in the amount of sodium ions that can enter the cell. If the opposite happens and the error bars DO overlap, then we say that the difference between the means in NOT statistically significant. This would mean that from our experiment we could NOT conclude that poison affects the amount of sodium ions entering the cell.

Calculations: Hardy-Weinberg Equilibrium 41. What the mathematical terms that represent each of the following: a. homozygous recessive genotype = q 2 b. heterozygous genotype = 2pq c.

7 Calculations: Hardy-Weinberg Equilibrium 41. What the mathematical terms that represent each of the following: a. homozygous recessive genotype = q 2 b. heterozygous genotype = 2pq c. recessive allele = q d. homozygous dominant genotype = p 2 e. dominant phenotype (all individuals that look dominant) = p 2 + 2pq f. recessive phenotype (all organisms that look recessive) = q 2 g. dominant allele = p 42. What do you need to do to give your answer as: a. frequency = leave it as a decimal b. percent = multiply your frequency x100 c. number of individuals ( How many organisms ) = multiply your frequency by the population size 43. See Topic #2 for practice problems. Youtube Hardy-Weinberg Problems Tutorial for additional help!

AP Biology Evolution Review Slides

AP Biology Evolution Review Slides How would one go about studying the evolution of a tetrapod limb from a fish s fin? Compare limb/fin structure of existing related species of fish to tetrapods Figure