Ch 11-sec 1-3
Pre-Test A- Answer Key
Multiple Choice 1. c 2. c 3. d 4. a 5. a 6. c 7. b 8. c 9. c 10. b 11. d 13. a 14. a
Completion 16. gametes, sex cells 17. round yellow seeds only 18. polygenic trait
Short Answer 19. Segregation happens when the alleles for each gene separate. Each gamete gets
only one allele for each gene. The principle of independent assortment states that the way alleles for
one pair of genes segregate does not affect the segregation of other alleles. 20. Thirty of the off spring
are expected to be tall and have yellow seeds. 21. 100% 22. Keep an arctic fox warm when its native
environment would be cool.
Essay 31. The tall pea plant should be crossed with a short pea plant. If the tall pea plant is
homozygous, all of the off spring will be tall. If the tall pea plant is heterozygous, it is likely that about
half of the off spring will be tall and half will be short. 32. When the heterozygous yellow-seed F1
plants produced gametes, their dominant allele for yellow seeds segregated from their recessive allele
for green seeds. As a result, some of their gametes had the dominant allele, and others had the
recessive allele. When the F1 plants self-pollinated, some male gametes with the recessive allele fused
with female gametes with the recessive allele during fertilization. Some of the off spring that resulted
had two alleles for green seeds and therefore had green seeds. 33. The kinds of off spring produced by
genetic crosses are the results of chance. For example, the number of gametes produced that contain
particular alleles is not certain. Likewise, the fusion of two gametes with particular alleles is not
certain. Thus, the results of genetic crosses shown in Punnett squares are just probable results. 34. The
alleles that determine flower color in four o’clock plants show incomplete dominance. She should use
pollen from white-flowered four o’clock plants to pollinate red-flowered four o’clock plants, or vice
versa. She should then collect seeds from the off spring. All of these hybrid seeds will produce only
pink-flowered four o’clock plants.