. In rye grass, seed color is a polygenic trait (additive model). If true-breeding red and white varieties are crossed, the F1 are intermediate in color. If the F1 are self-fertilized, about 1 in 64 have white seeds. If the F1 are testcrossed, how many different genotypic categories will be produced?
A. one
B. two
C. three
D. eight
E. 64
7. In rye grass, seed color is a polygenic trait (additive model). If true-breeding red and white varieties are crossed, the F1 are intermediate in color. If the F1 are self-fertilized, about 1 in 64 have white seeds; approximately how many of the F2 should be similar in color to the F1?
A. 1/64
B. 4/64
C. 6/64
D. 15/64
E. 20/64
8. A tall parent and a short parent produce intermediate F1 offspring that, when self-fertilized, produce a range of offspring heights, some taller than the tall P1 and some shorter than the short P1. Which set of parental genotypes could account for these data?
A. AABBCC x aabbcc
B. AABB x aabb
C. AABBcc x aabbC
D. AA x aa
E. AA x bb
9. Six additive loci control body weight in hamsters. Two extreme strains are crossed; the F1 are interbred to produce the F2. An F2 crop of hamsters that covers the complete range of weights (in a bell-shaped curve) is for sale. If a hamster costs $2 to raise, what did it probably cost to produce this F2 crop?
A. $64
B. $2,048
C. $4,096
D. $8,192
E. $16,384 or more
10. Six additive loci control body weight in hamsters. Two extreme strains are crossed; the F1 are interbred to produce the F2, which cover the complete range of weights (in a bell-shaped curve). If each allele that contributes to hamster weight adds 5 grams above a base weight of 100 grams, how much does the average F2 hamster weigh?
A. 100 g
B. 105 g
C. 125 g
D. 130 g
E. 150 g
11. Long- and short-eared strains of corn are crossed to produce offspring (F1) of intermediate ear length. When the offspring are self-fertilized, a wide range of ear lengths appears in their offspring (F2). About 1 in 1,000 of these F2 have ears as long as the parental long-eared race. Given an additive model of inheritance, how many loci are involved in ear length?
A. three
B. four
C. five
D. 6-10
E. >10
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