Ch 8 Practice Questions

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1 Ch 8 Practice Questions Multiple Choice Identify the choice that best completes the statement or answers the question. 1. What fraction of offspring of the cross Aa Aa is homozygous for the dominant allele? a. 1/64 b. 1/32 c. 1/16 d. 1/8 e. 1/4 2. What fraction of the offspring of the cross AaBb AaBb would show the dominant phenotypes for both genes? a. 3/16 b. 6/16 c. 9/16 d. 12/16 e. 1/3 3. Suppose unattached earlobes are a dominant trait. Phil and Maggie both have unattached earlobes but their daughter, Celia, does not. If Phil and Maggie have a second child, what is the probability that it will have attached earlobes? a. 1/8 b. 1/4 c. 1/2 d. 3/4 e The cross AaBb AaBb is an example of a cross; the results of such crosses led Mendel to propose what we now call the law of. a. self-; segregation of genes b. dihybrid; segregation of genes c. dihybrid; independent assortment d. test; segregation of genes e. test; independent assortment 5. In a test cross, peas of an unknown genotype are crossed with peas of a known genotype. In this example, smooth peas are the unknown and wrinkled peas are the known (rr). If half of the offspring from that cross are smooth and half are wrinkled, what is the genotype of the unknown plant? a. Incomplete dominance b. Homozygous dominant: RR c. Homozygous recessive: rr d. Heterozygous: Rr e. The genotype cannot be determined from the information given. 6. The 9:3:3:1 ratio is obtained a. through a dihybrid cross in which the genes are linked on the same chromosome. b. through a dihybrid cross in which the genes are on different chromosomes. c. when crossing over occurs. d. in a test cross.

2 e. None of the above 7. A dramatic departure from expected phenotypic ratios may be the result of a. environmental influences. b. genetic linkage. c. epistasis. d. heterosis. e. All of the above 8. is the term for when heterozygous offspring have superior fitness than their homozygous parents. a. Heterosis b. Incomplete dominance c. Codominance d. Epistasis e. Linkage 9. Codominance a. occurs when heterozygotes show a phenotype intermediate between those of the two homozygotes. b. involves the expression of both alleles at a locus producing two different phenotypes. c. is only found in mammalian enzyme production. d. involves one allele having more than one phenotypic effect. e. would result in pink flowers from a cross between white and red flowers. 10. Incomplete dominance a. results in a phenotypic ratio of 1:2:1 in the F 2 generation from a monohybrid cross. b. causes epistasis. c. is the same as codominance. d. involves the distinct expression of both alleles, as in the ABO blood group system. e. occurs only in X-linked genes. 11. A woman of blood group A has a child with a man of blood group B. The child s blood is type O. What are the genotypes of the parents? a. Mother: I A I A ; father: I B I a b. Mother: I A I O ; father: I B I b c. Mother: I A I O ; father: I B I O d. Mother: I A I B ; father: I B I O e. It is impossible for these individuals to have a child with type O blood. 12. Coat color in rabbits involves the effects of multiple gene interactions. If a rabbit has two recessive alleles (cc) for coat color, it is always albino no matter what the genotype of other genes involved in coat color. This is an example of a. pleiotropy. b. incomplete dominance. c. codominance. d. epistasis. e. heterosis. 13. The fact that a trait like height in humans varies over a wide range of values is due to a. penetrance. b. expressivity. c. multiple alleles and the environmental influences on the expression of these genes. d. epistasis.

3 e. discrete and qualitative genomic variation. 14. Which statement about linkage of genes is false? a. Genes on the same chromosome are said to be linked. b. Genes on the same chromosome assort independently. c. Crossing over between two linked genes can alter phenotypes of progeny. d. Crossing over results in recombinant phenotypes. e. Genes on the same chromosome that are far apart have a higher recombination frequency than those that are close together. 15. In many animals, including humans, sex is determined by a single, or by a pair of them. Both males and females have two copies of each of the rest of the chromosomes, which are called. a. sex chromosome; autosomes b. gene; autosomes c. autosome; sex chromosomes d. gene; sex chromosomes e. allele; genes 16. In sex-linked inheritance of a recessive gene, if a normal male and a heterozygous female carrier mated, all a. male offspring would show the trait. b. female offspring would be carriers. c. female offspring who receive the mutant X would show the trait. d. male offspring who receive the mutant X chromosome would show the trait. e. Both b and c 17. Wild type fruit flies have red eyes. A white-eyed female fly is crossed with a red-eyed male fly. All of the females from the cross are red-eyed and all of the males, white-eyed. What type of inheritance pattern is this? a. Independent assortment b. Autosomal dominant c. Autosomal recessive d. Incomplete dominance e. Sex-linked on X chromosome 18. Genes located on mitochondrial DNA are usually inherited a. randomly. b. from the mother. c. from the father. d. evenly from both the mother and the father. e. by independent assortment. 19. Lateral gene transfer between individuals of a species a. does not occur in bacteria. b. occurs by sexual reproduction in bacteria. c. can result in bacterial strains resistant to antibiotics. d. occurs only with plasmid DNA. e. always involves recombination. 20. Hemophilia A is an example of a disease that is inherited in a sex-linked manner. Which of the following statements about the inheritance of hemophilia A is false? a. The disease results from a lack of a protein factor needed for blood clotting. b. Females bearing one mutated X chromosome (carriers) are asymptomatic. c. Relatives who have the disease are likely to be males on the mother s side of the family. d. The disease is more likely to occur in males.

4 e. All males resulting from matings of a female carrier for the disease and a normal male would have the disease.

5 Ch 8 Practice Questions Answer Section MULTIPLE CHOICE 1. ANS: E PTS: 1 REF: Page SKL: 3. Applying 2. ANS: C PTS: 1 REF: Page SKL: 3. Applying 3. ANS: B PTS: 1 REF: Page SKL: 3. Applying 4. ANS: C PTS: 1 REF: Page ANS: D PTS: 1 REF: Page 149 SKL: 4. Analyzing 6. ANS: B PTS: 1 REF: Page ANS: E PTS: 1 REF: Page Page 156 Concept 8.3 Genes Are Carried on Chromosomes 8. ANS: A PTS: 1 REF: Page SKL: 1. Remembering 9. ANS: B PTS: 1 REF: Page SKL: 1. Remembering 10. ANS: A PTS: 1 REF: Page ANS: C PTS: 1 REF: Page SKL: 4. Analyzing 12. ANS: D PTS: 1 REF: Page ANS: C PTS: 1 REF: Page ANS: B PTS: 1 REF: Page TOP: Concept 8.3 Genes Are Carried on Chromosomes 15. ANS: A PTS: 1 REF: Page TOP: Concept 8.3 Genes Are Carried on Chromosomes SKL: 1. Remembering

6 16. ANS: D PTS: 1 REF: Page TOP: Concept 8.3 Genes Are Carried on Chromosomes SKL: 4. Analyzing 17. ANS: E PTS: 1 REF: Page 159 TOP: Concept 8.3 Genes Are Carried on Chromosomes SKL: 4. Analyzing 18. ANS: B PTS: 1 REF: Page TOP: Concept 8.3 Genes Are Carried on Chromosomes 19. ANS: C PTS: 1 REF: Page TOP: Concept 8.4 Prokaryotes Can Exchange Genetic Material 20. ANS: E PTS: 1 REF: Page TOP: 8.5 Answer to Opening Question SKL: 4. Analyzing

Name Class Date. Review Guide. Genetics. The fundamental principles of genetics were first discovered by. What type of plant did he breed?.

Name Class Date. Review Guide. Genetics. The fundamental principles of genetics were first discovered by. What type of plant did he breed?. Name Class Date Review Guide Genetics The fundamental principles of genetics were first discovered by. What type of plant did he breed?. True-breeding parental plants are called the generation. Their hybrid