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 plantsĆ¢ĀĀone with white flowers and one with pinkĆ¢ĀĀto 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
