11. You suspect that two genes interact with one another to determine the product of a pathway you are studying. You cross two pure breeding plantsâone with white flowers and one with pinkâto make F1 individuals that have blue flowers. You cross the F1 generation and observe the following numbers of individuals with different phenotypes: Number of individuals Phenotype 91 Blue 30 Pink 39 White Which pathway best explains these results? (Note that arrows indicate enzymatic reactions carried out by products of genes 1 and 2. Assume that buildup of metabolites will determine flower color.)
Question 12 and 13: Consider the biochemical pathway presented below. This pathway determines pigment production in pea flowers. (Note: gene products are required for each reaction to proceed.)
12. Do you expect that genes A and B will interact with one another?
A. Yes B. No C. Insufficient information to determine
13. What phenotype ratio would you expect in offspring produced by crossing AaBb parents?
A. 9:3:3:1 (blue : green : yellow : white) B. 9:3:4 (blue : green : white) C. 9:7 (blue : white) D. 15:1 (blue : white)
14. How can haplosufficiency explain dominance of an allele that codes for a functional protein over a null (loss of function) allele?
A) a single functional copy of the gene produces sufficient gene product for normal biological function B) a single functional copy of the gene produces insufficient gene product for normal biological function C) the null allele produces a product that interferes with proper function of the normal allele D) the null allele produces a product that does not interfere with proper function of the normal allele E) the null allele rapidly mutates to reacquire normal functionality
15. In a plant species with genes A and B, you have isolated recessive mutant alleles at each locus, which you call a and b. You would like to know whether these two genes are linked. To test this hypothesis, you obtain an individual that is heterozygous at both genes (AB/ab) and perform a test cross. Which results would be most consistent with these loci being tightly linked? (Results are counts of the numbers of offspring from the testcross.)
A. Ab/ab 390 aB/ab 410 AB/ab 350 ab/ab 420
B. Ab/ab 80 aB/ab 73 AB/ab 760 ab/ab 754
C. Ab/ab 700 aB/ab 695 AB/ab 56 ab/ab 59
D. Ab/ab 400 aB/ab 65 AB/ab 50 ab/ab 659
