2011+Midterm+2+answer+key

2011+Midterm+2+answer+key - Name (Signature)_Student ID #_...

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Name (Signature)___________________________________Student ID #__________ BIS2B Midterm 2. Rosenheim ANSWER KEY Winter 2011 DO NOT OPEN THIS PACKET UNTIL INSTRUCTED TO DO SO IMPORTANT INSTRUCTIONS -- READ FIRST 1. Put your name and student ID number on every page. 2. Make sure you have every page of this exam. There are 8 pages and 12 questions. Total: 100 points. 3. On the examination, write all answers in pen . 4. We cannot accept re-grade requests for exams written in pencil or that have whiteout. 5. On the SCANTRON forms use a #2 pencil. 6. Be sure to put your name, student ID on the SCANTRON . 7. Also on the SCANTRON, bubble in Test Form “ A”. 8. Simple (non-graphing) calculators are allowed. p 4 p 5 p 6 p 7 p 8 1
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Name (Signature)___________________________________Student ID #__________ Questions 1-8: Multiple choice questions (5 points each; total 40 points) Select one best answer and mark SCANTRON form using a #2 pencil. Be sure to put your name and student ID on the SCANTRON (and circle the answer on the exam). 1. Mendel’s First Law focuses on segregation of two alleles, say A 1 and A 2 , found at a single locus in a diploid, sexually reproducing species. This law tell us a. that the two alleles cannot both be expressed in the phenotype of the organism, producing a trait value that is intermediate between the trait value expressed by A 1 A 1 or A 2 A 2 individuals b. that crossing over during meiosis can generate novel combinations of the A 1 and A 2 alleles c. that A 1 A 2 heterozygotes produce two types of gametes, one carrying the A 1 allele and the other carrying the A 2 allele. d. that inheritance operates through a blending mechanism. e. all of the above are true Answer: c 2. Selection against a deleterious (= harmful) recessive allele seems to “slow down” as the frequency of the allele gets very small because a. the fitness of individuals that are homozygous for the recessive allele improves as the frequency of the allele decreases b. selection only acts against heterozygotes that carry one copy of the deleterious recessive allele c. selection only acts against homozygotes that carry two copies of the deleterious recessive allele d. genetic drift becomes the dominant force of evolution when the recessive allele becomes very rare e. the fitness of individuals that are homozygous for the dominant allele becomes more nearly equivalent to the fitness of heterozygotes as the recessive allele becomes very rare Answer: c 3. Genetic drift a. can contribute to changes in allele frequencies, even when those same alleles are influenced by natural selection b. operates only on neutral traits (i.e., traits that have no influence on fitness) c. operates most powerfully in large populations, because large populations generate a larger number of novel genetic variants d. acts as an important source of novel genetic variants within populations e. is a dominant source of key adaptations in many plant and animal species Answer: a 4. Whereas insecticide resistance evolution has frequently been observed in populations of pest insects
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This note was uploaded on 10/23/2011 for the course BIS 101 taught by Professor Simonchan during the Spring '08 term at UC Davis.

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2011+Midterm+2+answer+key - Name (Signature)_Student ID #_...

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