Monohybrid Cross Problem Set

Problem 4: A cross of F1-hybrid plants

Tutorial to help answer the question

A genetic cross between two F1-hybrid pea plants for spherical seeds will yield what percent spherical-seeded plants in the F2 generation? (Recall, spherical-shaped seeds are dominant over dented seeds.)


Crossing two heterozygotes
The parent plants are heterozygous for an allele that determines seed shape. We can use a Punnett square to predict the phenotypes of their offspring.

The F1-hybrid plants have the dominant (S), spherical seed phenotype. In the Punnett square, we see that one out of four possible combinations of F2-generation plants has the homozygous recessive genotype (ss).


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Thursday, October 1, 1998
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