Question

Assume that there is a gene in apples that determines fruit color and a second gene that determines fruit size. Let A represent the dominant allele for big apples, and a represent the recessive allele for small apples. Similarly, let R represent the dominant allele for red apples, and r represent the recessive allele for yellow apples. You have one tree that produces big yellow apples and another tree that produces small red apples. When the two are crossed, you find that half of the new trees produce big red apples and half produce big yellow apples. What are the genotypes of the parents?

Answer 1

Answer:

Parent with big yellow apple= AArr

Parent with small red apple= aaRr

Explanation:

According to the given information, all the progeny has big apples and the trait "small size" is not expressed in any of them. This means that the parent plant with "big" apples was homozygous dominant and had an "AA" genotype. This is why there was no segregation of alleles and all the progeny had "big" apples.

On the other hand, both "red" and "yellow" colored apples were obtained in the progeny. This means that the parent plant with "red" apples was heterozygous for the trait "Rr". Segregation of "R" and "r" alleles during gamete formation led to the production of two types of gametes. Half of the gametes from this parent plant have an "R" allele while the rest half have an "r" allele.

Therefore, the genotype of parent plants are as follows"

Parent with big yellow apple= AArr

Parent with small red apple= aaRr