A test cross with an organism with a homozygous recessive genotype results in 50% of the offspring exhibiting the recessive trait. What is the genotype of the test-cross parent?

I. Homozygous recessive
II. Homozygous dominant
III. Heterozygous

A. I only
B. II only
C. III only
D. I or III
E. II or III

The answer is heterozygous.
If it was crossed with homozygous dominant, then 100% of the offspring would show the dominiant trait. If it was homozygous recessive 100% of the offspring would have the recessive trait

Answered by sc8688 | 2024-06-10

I say C. III ONLY, because if you put this all out on a punnet chart that is the only one that comes out with a correct outcome, 50%, so I say it is heterozygous only, answer choice C!
Hope this helps, if not, comment below please!!!!

Answered by Anonymous | 2024-06-12

The genotype of the test-cross parent is heterozygous (Aa) because a 50% expression of the recessive trait indicates that the dominant parent must have one recessive allele. This is a result of performing a test cross with a homozygous recessive parent. Therefore, the answer is III.
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Answered by sc8688 | 2024-12-23