This is the complete 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:
AArr and aaRr
Explanation:
From the question, we are given that;
Let A represent the dominant allele for big apples; &
a represent the recessive allele for small apples.
Similarly, let R represent the dominant allele for red apples; &
r represent the recessive allele for yellow apples.
After Crossing, half of the new trees produces Big red apples (i.e AaRr or AARR) & Half produce big yellow apples (i.e Aarr or AArr)
Now, lets assume that the genotypes of the parents are AArr and aaRr
If AArr self crossed; we have = ( Ar, Ar, Ar, Ar)
aaRr will be ( aR, ar, aR, ar)
Now, if these F1 offspring crossed, we have;
Ar Ar Ar Ar
aR AaRr AaRr AaRr AaRr
ar Aarr Aarr Aarr Aarr
aR AaRr AaRr AaRr AaRr
ar Aarr Aarr Aarr Aarr
From above, we can see that; we have the 8 offspring possessing AaRr genotypes and Aarr genotypes.
8 AaRr : 8 Aarr
AaRr implies big red apples as; A-a (heterozygous for big apple allele mask the effect of the recessive small allele which makes it to be dominant big apple).
Also R-r (heterozygous for red allele mask the effect of the recessive yellow allele which makes it to be dominant red color)
On the other hand, Aarr implies Big yellow apples as; A-a (heterozygous for big apple allele mask the effect of the recessive small allele which makes it to be dominant big apple).
Also rr = (recessive yellow traits)
Therefore, from the foregoing we can conclude that the progenitor whose genotypes are AArr and aaRr are the right match to produce half of the offspring trees with big red apples and half offspring trees with big yellow apples.
