Question

Suppose a researcher performed an experiment to determine the number of genes affecting fruit size in tomatoes. She crossed a domesticated, heirloom tomato plant with a wild tomato plant for two generations to obtain F2 individuals. In the parental lines, the domesticated tomatoes had a fruit diameter of 17 cm and the wild tomatoes had a fruit diameter of 5 cm.

If fruit size is an additive genetic trait, what number of genes should we expect to contribute to this phenotype? Use the data below. Your answer should be expressed numerically (no words).

Height	Number of individual plants
5 cm	1
7 cm	4
9 cm	16
11 cm	22
13 cm	15
15 cm	5
17 cm	1

The relative fitness of the A¹A¹ genotype is 1.0, the relative fitness of the A¹A² genotype is 0.8, and the relative fitness of the A²A² genotype is 0.6. The A¹ allele should                            ["stay the same", "increase", "decrease"]         in the next generation, and it is likely           ["incompletely dominant", "completely dominant"]         with respect to the A² allele.

Answer 1