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AGR 3303 (3 credits) University of Florida - Fort Lauderdale  |
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| Below is exam #3 for 1996, Advanced genetics |
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AGR 3303 - Genetics 21 Nov 1996 University of Florida - Fort Lauderdale Exam #3: ADVANCED GENETICS Student name_______________________________ 110 pts. total Multiple choice (48 pts.) Please read each question carefully. Do not be misled if you are familiar with a similar looking question which you have seen before. One and only one response (a, b, c, d, or e) completely and correctly answers the question, or completes the statement. Circle the appropriate response on this exam, which will be turned in. Make sure your circle is unambiguous. Take time to relax. 1. Qualitative traits: a. are the kinds observed by Mendel b. are probably atypical c. are recorded in categories d. are controlled by few genes e. all of the above 2. In the lac operon: a. lactose represses the transcription of structural genes b. posttranscriptional control reduces unnecessary enzyme production c. when there is lactose present, the structural genes are transcribed d. lactose enables the repressor to bind to the operator region e. there is a regulatory cascade regulated by hormones 3. For a mutation, (e.g., nucleotide substitution) in a structural gene to be expressed: a. the genotype must be heterozygous b. the altered triplet codon must be redundant c. the enzyme must be monomeric d. the enzyme active site must be affected e. none of the above 4. Philip Busey's main criticism of associating intelligence and race is: a. intelligence tests are a cultural product b. people misreport their race c. there is no genetic variation among humans d. it's not nice e. underprivileged people's intelligence can be lowered by malnutrition
5. In eukaryotes, the immediate result of translation is: a. an enzyme b. a protein c. a polypeptide d. mRNA e. none of the above 6. It is believed that the eukaryotic chromosome can protect DNA from enzymatic action: a. by tight coiling b. during cell division c. to turn genes off d. all of the above e. none of the above 7. A cross between two heterozygotes will lead to: a. a narrow distribution of F1 heterozygotes b. homogeneous progeny c. homozygous progeny d. two progeny peaks e. none of the above 8. Small, isolated populations have a role in evolution because: a. small populations are more likely to lose genes due to chance (genetic drift) b. natural selection can favor adaptation to local conditions c. inbreeding is more likely to occur d. all of the above e. none of the above 9. A word for one gene affecting two or more traits: a. heritability b. epistasis c. pleiotropy d. polygenes e. multiple alleles 10. Gene regulation in prokaryotes operates during transcription because: a. prokaryotes respond to hormone/receptor protein complexes b. transcription and translation are simultaneous in prokaryotes c. the triplet codons determine the primary structure of the enzymes d. they may be endosymbionts e. of the need for a regulatory cascade 11. In the lac operon, a. there are three regulatory genes and one structural gene b. lactose binds with a protein, preventing translation c. a protein binds with the mRNA, preventing translation d. lactose binds with the DNA, preventing transcription e. translation produces enzymes which catabolize lactose 12. The most likely explanation for the relationship between radiation and cancer is: a. radiation leads to nucleotide subsitution(s), which result in the wrong amino acid(s) in the active site of enzymes b. genes regulating cell division are rendered ineffective c. most proteins are oligomers d. all of the above e. none of the above 13. Ten individuals of a bisexual species (e.g., a plant capable of either self- or cross-fertilization) establish a colony on a remote island. One of the original individuals is homozygous recessive for white flowers. The remaining nine individuals are homozygous dominant, thus they have purple flowers. After several generations the island is visited by a botanist, who notices individuals with purple flowers and individuals with white flowers. Assuming Hardy-Weinberg equilibrium and no change in the frequency of alleles since the original establishers, what frequency of white flowers does the botanist notice? a. 1% b. 2% c. 4% d. 8% e. 10 % 14. The number of genes controlling a trait in which each of the two extreme genotypes represents 1/16 of the progeny from a heterozygote (polygenic inheritance, no dominance): a. 1 b. 2 c. 3 d. 4 e. cannot be determined
15. The human genome project could help people because: a. genetic diseases cannot be diagnosed without sequencing the genes b. by sequencing the genes associated with a disease, scientists can identify the proteins responsible, and find the mechanism of the disease c. we should soon be able to breed better people d. once you have identified a gene, it is easy to find a cure e. there is no way that the human genome project can help 16. Coat color in cats is determined by the sex-linked alleles B (black) and b (yellow). Except, heterozygous females are tortoise-shelled (calico). A population of cats had the following phenotypic frequencies:
What is the frequency of the B allele? a. 0.33 b. 0.38 c. 0.40 d. 0.50 e. cannot be determined
True or false? (15 pts.) Each statement is either true or false. Telling only part of the truth does not make a statement false. Please circle T for true or F for false. 17. T F Natural selection occurs because of Hardy-Weinberg equilibrium. 18. T F Normal cells usually undergo a finite number of cell divisions. 19. T F Each chiasma is equal to 1% crossing over (1 map unit). 20. T F The limit of recombination is 50%. 21. T F Two populations with identical allelic frequencies must have identical genotypic frequencies.
22. T F Mitochondrial DNA is considered to act as a molecular clock. 23. T F Eukaryotic gene regulation involves a specific RNA polymerase for each gene. 24. T F If a population inbreeds, it will tend to become homogeneous. 25. T F Evolution by natural selection is accepted by scientists as a fact. 26. T F The frequencies of linked genes approach equilibrium more rapidly if they have a large map distance. 27. T F Matings between siblings are the most extreme form of inbreeding possible among sexually reproducing species. 28. T F The frequency of a sex-linked gene in XX females is equal to the frequency in males (XY) in the previous generation. 29. T F The polymerase chain reaction is the process of determining the order of nucleotides. 30. T F Chemical warfare is practiced by the immune system. 31. T F The AIDS virus is known to mutate rapidly.
Short answer 32. What four conditions must be met for Hardy-Weinberg equilibrium? (8 pts.)
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33. Coat color in cats is determined by the sex-linked alleles B (black) and b (yellow). Except, heterozygous females are tortoise-shelled (calico). A population of cats has the allelic frequencies of p=0.5 and q=0.5. Assuming Hardy-Weinberg equilibrium, what are the phenotypic frequencies of a population of 200 cats (100 males and 100 females)? (6 pts.)
34. What is the genetic problem of maintaining populations of large animals, and why is it a problem? (5 pts.)
35. A population of humans migrates from Western Island to the United States. After many generations, their ABO blood group allele frequencies change to values more similar to the endemic population of the United States, and less like their original frequencies. Does this prove that the Western Islanders' gene pool has been diluted through interbreeding with the endemic United States residents? List an alternative explanation and justify whether it is plausible or not. (6 pts.) 36. Populations including people can have a surprisingly high frequency of recessive lethal alleles, which is called genetic burden or genetic load. Probably each of us has several lethal alleles. A few examples among the many lethal alleles in humans involve the genes for sickle-cell anemia, muscular dystrophy, and Huntington's disease. Yet according to Darwin's theory of natural selection, there should be selection for fitness, which we now know is controlled by the genes. Why do we have lethal alleles and why aren't they eliminated by natural selection? (8 pts.)
37. You are a consultant on a golf course which has patches of different colored grass on the greens. It is your job to determine whether the patches are explained as being a different genetic variety of grass than the surrounding matrix. How would you determine this? (Make sure to state an alternative hypothesis which might explain the different colors. Make sure to say what kind of evidence you would obtain, and how you would obtain it, to accept or reject the alternative hypotheses.) (6 pts)
38. When a mutation (e.g., a nucleotide substitution) occurs in a structural gene, several conditions must exist in order for the mutation to be expressed. Name at least four conditions. (8 pts.)
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