BIO 102 Exam (2013)

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BIOL 102
Timothy L I N K S V A Y E R

Biology 102 – First Midterm – Spring 2013 Your signature below certifies that you have complied with the Code of Academic Integrity of the University of Pennsylvania in taking this exam. This code with be strictly enforced! Signature___________________________________________________________ Your Name (print): __________________________________________________ • DO NOT OPEN YOUR EXAM UNTIL YOU ARE TOLD TO DO SO. • This is a closed book exam. You will have 50 minutes to complete the exam. • Make sure you have a complete exam (11 pages, 40 questions). • You must use a pen to complete this exam. Do not use red ink, pencil or white-out on the exam. • Please be sure to budget your time so that you can complete the entire exam, including both multiple choice and short answer questions. For multiple choice questions, circle the letter of the single best answer. On short answer questions, confine your answer to the space provided and write legibly. • If a question appears ambiguous, ask a proctor; proctors will answer questions only if they feel that your question reveals a genuine ambiguity in the wording of the question. Page Questions Possible Points Points Received 2 1-4 8 3 5-7 6 4 8-12 10 5 13-16 8 6 17-21 10 7 22-26 10 8 27-31 10 9 32-35 8 10 36-39 24 11 40 6 Total 100 Multiple Choice: choose the single best answer (2 points each) 1. In order for a trait such as drug resistance to evolve by natural selection, three requirements must be met. Which of the following is NOT one of the requirements: A. Population size must be extremely large X B. There must be variation for drug resistance within the population C. Drug resistance must be heritable D. Drug resistance must affect survival or reproductive output 2. If a rare and harmful genetic disorder spreads in a population across generations, the population is most likely: A. Very large B. Very small X C. Experiencing purifying selection D. Experiencing strong positive selection E. Experiencing strong balancing selection 3. Organisms never perfectly fit their environment. Which of the following is NOT a reason for this imperfect match? A. Historical constraint B. Mutation C. Changing environmental conditions D. Gene flow E. Selection X F. Organisms are constrained by the laws of physics 4. Over time, populations often adapt to their local environment. Migration from neighboring populations can often introduce alleles that are less-well matched. This process is a balance of evolutionary forces called: A. Mutation-selection balance B. Drift-selection balance C. Gene flow-selection balance X D. Inbreeding depression E. Outbreeding depression F. Dobzhansky-Muller incompatibility 5. Over time, populations that are almost completely isolated by geographic barriers tend to diverge. Which of the following is an evolutionary force that does NOT contribute to this divergence? A. Gene flow X B. Selection C. Mutation D. Drift E. Allopatric speciation 2 F. Sympatric speciation 6. Imagine a population where the males that obtain the most mates are very large or very small relative to other males. What pattern of selection best describes this situation? A. Directional selection on body size B. Stabilizing selection on body size C. Disruptive selection on body size X D. Positive selection on body size E. Frequency dependent selection on body size 7. In the phylogeny above, which of the following commonly used groupings actually reflects evolutionary relationships (i.e. is monophyletic)? A. Warm-blooded vertebrates (Pigeon + Mouse + Chimpanzee) B. Reptiles (Lizard + Crocodile) C. Cold-blooded vertebrates (Perch + Salamander + Lizard + Crocodile) D. Fish (Lamprey + Perch) E. Mammals (Mouse + Chimpanzee) X 8. Your genome likely has 3-5 million single nucleotide differences from the person sitting next to you. Given the content of the human genome, where do you expect to find most of these single nucleotide differences? A. Protein coding regions B. Non-coding regions, some of which are involved in regulating gene expression X C. In duplicated genes D. In mitochondrial genes E. In choloroplast genes 9. What is the ultimate source of all genetic variation? 3 A. Gene flow B. Selection C. Mass extinction D. Synonymous substitution E. Sexual reproduction F. Drift G. Mutation X 10. Which varies most among organisms across the tree of life? A. Genome size X B. Gene number C. Number of different types of nucleotides D. Number of different types of amino acids 11. Approximately what fraction of the total age of the Earth (approximately 4.5 billion years) passed before life existed? A. 0.05 (approximately 0.23 billion years) B. 0.15 (approximately 0.68 billion years) X C. 0.33 (approximately 1.5 billion years) D. 0.50 (approximately 2.3 billion years) E. 0.75 (approximately 3.4 billion years) 12. What process was responsible for the gradual increase in the percent oxygen on earth from 0 to ~5% over the first 3.5 billion years of the earth’s existence? A. The breakup of water (H O2 by ultraviolet radiation B. Bombardment of earth by comet fragments containing liquid oxygen C. Photosynthesis by bacteria X D. Photosynthesis by plants E. Respiration by aerobic bacteria F. Respiration by aerobic multicellular animals 13. During the earth’s history several mass extinction events occurred. Based on what you learned about the evolutionary forces, which force would you expect to become more important after the mass extinction event, as a result of the drastic decrease in population size? A. Selection B. Drift X C. Gene flow D. Mutation E. Recombination F. Meiotic drive 14. Assume that a mass extinction event was caused by a volcanic eruption that greatly increased 4 the atmospheric concentration of a toxic gas. If individuals survived depending on whether they possessed the ability to deal with the toxic gas, what evolutionary force would be responsible for the likely spread of resistance to the toxic gas among survivors of the catastrophe? A. Selection X B. Drift C. Gene flow D. Mutation E. Recombination F. Meiotic drive 15. The morphological species concept can often reflect evolutionary relationships because similar looking organisms are often genetically similar. Which of the following best describes limitation(s) of the morphological species concept that drive(s) many biologists to favor one of the other species concepts we discussed? A. Organisms from widely diverged lineages may look remarkably similar B. Males and females from the same population often look different C. Some organisms do not reproduce sexually, so that reproductive isolation is not a valid criterion for defining species D. It is often difficult to determine whether any two individuals can reproduce E. A and B X F. A and E 16. If an amino acid position is under purifying selection, what can you say about the rate of non- synonymous relative to synonymous substitutions? A. The rate of non-synonymous substitutions should be much higher than the rate of synonymous substitutions. B. The rate of synonymous substitutions should be much higher than the rate of non-synonymous substitutions. X C. The rate of synonymous substitutions should be approximately equal to the rate of non- synonymous substitutions. 17. Gene duplication results in two copies of a gene and can lead to the evolution of novel functions. Which of the following processes must occur for novel functions to evolve? A. Synonymous substitution B. Nonsynonymous substitutio
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