1. Cancer is a disease in which cells a. grow and divide uncontrollably. b. die before they can mature.

c. stop producing DNA. d. die during mitosis.

2. Which of these traits is controlled by a gene with multiple alleles?

a. straight hairline b. smile dimples

c. widow’s peak d. blood type

3. Which of these is an example of the benefits of genetic engineering?

a. cross-breeding to create disease-resistant crops

b. creating human insulin to treat people with diabetes

c. analyzing karyotypes and pedigree charts

d. growing a new plant from a cutting

4. A carrier is a person who has

a. one recessive and one dominant allele for a trait.

b. two recessive alleles for a trait.

c. two dominant alleles for a trait.

d. more than two alleles for a trait.

5. Sex-linked genes are genes on

a. the X chromosome only. b. the Y chromosome only.

c. the X and Y chromosomes. d. all 23 pairs of chromosomes.

6. What is the chromosome theory of inheritance?

a. Chromosomes are carried from parents to offspring on hybrids.

b. Genes are carried from parents to offspring on chromosomes.

c. Hybrid pairs of chromosomes combine to form offspring.

d. Codominant genes combine to form new hybrids.

7. How can a mutation affecting skin be harmful to an animal?

a. It can make the animal more visible to its prey or predators.

b. It can cause disease in the animal.

c. It can make the animal resistant to certain diseases.

d. It can make the animal resistant to drugs

8. What happens during meiosis?

a. Two sex cells combine.

b. Chromosome pairs separate and are distributed into new sex cells.

c. Each sex cell copies itself to form four new chromosomes.

d. Chromosome pairs remain together when new sex cells are formed.