Dihybrid Cross

Problem 1: Predicting combinations of alleles in gametes of plants heterozygous for two traits.

A pea plant is heterozygous for both seed shape and seed color. S is the allele for the dominant, spherical shape characteristic; s is the allele for the recessive, dented shape characteristic. Y is the allele for the dominant, yellow color characteristic; y is the allele for the recessive, green color characteristic. What will be the distribution of these two alleles in this plant's gametes?

A. 50% of gametes are Sy; 50% of gametes are sY
B. 25% of gametes are SY; 25% of gametes are Sy;
25% of gametes are sY; 25% of gametes are sy.
C. 50% of gametes are sy; 50% of gametes are SY
D. 100% of the gametes are SsYy
E. 50% of gametes are SsYy; 50% of gametes are SSYY.

The Biology Project
University of Arizona
Friday, August 9, 1996
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