Section 9-1
VOCABULARY REVIEW
1. The F1 generation consists of the offspring of a cross between two parents; the F2 generation consists of the offspring of a cross between two individuals in the same F1 generation.
2. A dominant factor is one that masks the effect of another factor for the same characteristic; a recessive factor is one whose effect is masked by another factor for the same characteristic.
3. Self-pollination occurs between flowers on the same plant. Cross-pollination occurs between flowers on different plants.
MULTIPLE CHOICE
1. c 2. a 3. d 4. b
SHORT ANSWER
1. An allele is each of two alternative forms of a gene. 2. In meiosis, the two alleles of each gene are segregated when the two chromosomes in each pair of homologues are separated into different gametes.
Alleles of genes located on different chromosomes or far apart on the same chromosome assort independently when homologues are randomly separated during meiosis.
3. Orange flower color is dominant. All of the F1 plants will have orange flowers.
4. Mendel would have observed that the traits controlled by dominant factors for these characteristics almost always appeared together. Thus, he might not have concluded that the factors for different characteristics are assorted independently.
STRUCTURES AND FUNCTIONS
Possible combinations are RB, Rb, rB, and rb.
Section 9-2
VOCABULARY REVIEW
1. In complete dominance, heterozygous and dominant homozygous individuals have the same phenotype.
For example, in pea plants, the P allele is completely dominant over the p allele, so both PP and Pp plants have purple flowers.
2. In incomplete dominance, neither allele is completely dominant over the other and both influence the phenotype. For example, in four o’clocks, neither the R nor r allele is completely dominant, so Rr plants have pink flowers.
3. In codominance,