Dihybrid Cross

Problem 6: Offspring of a SsYy x ssyy test cross.

Tutorial to help answer the question

The expected phenotypic ratio of the progeny of a SsYy x ssyy test cross:

Tutorial

Alleles of parent 1

There are four combinations of alleles in the gametes from partent 1.

Alleles of parent 2

There is only one possible combination of alleles in the gametes from parent 2.

Test Cross

This cross can be used to determine if this spherical yellow seeded plant was heterozygous for either the seed shape or seed color trait.

Phenotype of offspring

Each of the genotypes of the offspring corresponds to a different phenotype.

SsYy are smooth, yellow seeded
Ssyy are smooth, green seeded
ssYy are dented, yellow seeded
ssyy are dented, green seeded
These phenotypes will appear in a predicted 1:1s:1:1 ratio.

The Biology Project
University of Arizona
Tuesday, August 13, 1996
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