Practice_questions_for_Exam_3_SS12_and_k - Exam 3 BS 162...

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Exam 3 BS 162 Spring 2012 Practice exam questions 1. You cross a white rose and a red rose. The first generation of offspring are all red, but in the second generation three flowers are red for every white flower. What most likely happened? A) A new mutation for white flowers appears in the second generation B) Red is more powerful than white and usually wins in the struggle for expression of flower color C) the allele for white flowers is dominant to the red flower allele D) the allele for red flowers is dominant to the white flower allele 2. Albinism in humans occurs when both alleles at a locus produce defective enzymes in the biochemical pathway leading to melanin. Heterozygotes are normally pigmented. Thus, which of the following statements is correct? A) One normal allele produces as much melanin as two normal alleles. B) Each defective allele produces a little bit of melanin. C) Two normal alleles are needed for normal melanin production. D) The two alleles are codominant. E) The amount of sunlight will not affect skin color of heterozygotes. 3. Imagine a locus with four different alleles for fur color. The alleles are D a , D b , D c , and D d . If you crossed two heterozygotes, D a D b and D c D d , what genotype proportions would you expect in the offspring? A) 25% D a D c , 25% D a D d , 25% D b D c , 25% D b D d B) 50% D a D b , 50% D c D d C) 25% D a D a , 25% D b D b , 25% D c D c , 25% D d D d D c D d D) 50% D a D c , 50% D b D d E) 25% D a D b , 25% D c D d , 25% D c D c , 25% D d D d 4. Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of the cross BbTt × BBtt will have black fur and long tails? A) 1/16 B) 3/16 C) 3/8 D) 1/2 E) 9/16 5) What is the reason that linked genes are inherited together? a. They are located close together on the same chromosome. b. The number of genes in a cell is greater than the number of chromosomes. c. Chromosomes are unbreakable. d. Alleles are paired together during meiosis. e. Genes align that way during metaphase I of meiosis. 6) In a pedigree analysis, carriers can be inferred to occur a. when they exhibit the trait in question but their offspring do not. b. when they are homozygous for the trait in question.
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c. when they have only one X chromosome. d. when they do not exhibit the trait in question but some of their offspring do. 7) What is the mechanism for the production of genetic recombinants? a. X inactivation b. Methylation of cytosine c. Crossing over and independent assortment d. Nondisjunction e. Deletions and duplications during meiosis 8) X-linked traits a. are those on either the X or Y chromosomes. b. are those on autosomal chromosomes. c. are the same as linked genes.
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This note was uploaded on 04/02/2012 for the course BS 162 taught by Professor Pamelarasmussen during the Spring '12 term at Michigan State University.

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Practice_questions_for_Exam_3_SS12_and_k - Exam 3 BS 162...

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