1. 1. A scientist observes that a certain trait is determined by a single allele. An organism inherited one version of the trait from one parent and another version from the other parent. Both versions of the trait are expressed in the phenotype of the offspring. Which pattern of inheritance best classifies the observed trait? A. dominance b. sex-linkage c. co-dominance d. incomplete dominance

2. c. Co-dominance

3. 2. An organism that has inherited two of the same alleles of a gene from its parents is ______________ for that trait. a. hereditary b. heterozygous c. homozygous d. hemizygous

4. c. homozygous

5. 3. If a characteristic is X-linked, it a. occurs mostly in males. b. occurs only in males. c. occurs mostly in females. d. occurs only in females.

6. A. Occurs mostly in males

7. Questions 4–5 refer to the figure below, which shows a cross between two rabbits. In rabbits, black fur (B) is dominant to brown fur (b). 4. The fur in both of the parents in the cross is a.black. b.brown. c. homozygous dominant. d.homozygous recessive.

8. a. black

9. 5. The phenotype of the offspring indicated by Box 3 would be a.brown. b.a mixture of brown and black. c.black. d.The phenotype cannot be determined.

10. c. black

11. 6. If an individual with a dominant phenotype is crossed with an individual with a recessive phenotype, four of their nine offspring show the recessive phenotype. What is the genotype of the first parent? a. AA b. Aa c. aa d. The answer cannot be determined from this information.

12. b. Aa

13. 7. If the genotype of an organism is YySsTt, then yST would represent a. the genotype of the offspring. B. a possible phenotype of the offspring. C. gamete of the parent. D. possible zygote.

14. c. Gamete of the parent

15. 8. A man with blood type AB could not be the father of a child with a. blood type A. b. blood type B. c. blood type AB. d. blood type O.

16. d. Blood type O

17. 9. Crossing a snapdragon that has red flowers with one that has white flowers produces a snapdragon that has pink flowers. The trait for flower color exhibits a.multiple alleles. b.incomplete dominance. c.complete dominance. d.codominance.

18. b. Incomplete dominance

19. 10. What is the relationship between DNA, chromosomes, and genes?

20. Chromosomes contain DNA and protein DNA contains genes