Dihybrid Cross

Problem 11: Incomplete dominance in a dihybrid cross.

Correct!

In Mendel's experiments, the spherical seed character (SS) is completely dominant over the dented seed character (ss). If the characters for height were incompletely dominant, such that TT are tall, Tt are intermediate and tt are short, what would be the phenotypes resulting from crossing a spherical-seeded, short (SStt) plant to a dented-seeded, tall (ssTT) plant?

A.
All the progeny would be spherical-seeded and tall.
B.
1/2 would be spherical-seeded and intermediate height; 1/2 would be spherical-seeded and tall.
C.
All the progeny would be spherical-seeded and short.
D.
You cannot predict the outcome.
E.
All the progeny would be spherical-seeded and intermediate height.
All of the offspring would have the genotype of SsTt. Mendel selected traits to study that did not display partial dominance. Could you predict the result of an SsTt x SsTt cross if one or both traits dispayed partial dominance? There would be 9 different phenotypes if both traits showed partial dominance.


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