Yellow eyes are dominant to purple eyes. Cross a carrier with a yellow eyed person....?

Question

what percentage of the offspring are carriers?


I would think 100%..

Answer 1

Well the carrier would have to have an eye color more dominant than yellow eyes, lets say for arguments sake that the carrier has red eyes. The person with yellow eyes could have two yellow eyed genes or a yellow and a purple. As there would be no way to tell short of extensive DNA tests to determine if the yellow eyed person has two yellows or a yellow and a purple, we will go with the assumption that they have a yellow and a purple.

Yellow Eyed (Yp) Carrier (Ry)
The four combos would then be yR, YY, pR, pY

That is a 75% chance that the offspring would be carriers.

Answer 2

The question is carefully worded, it appears!
if yellows are dominant then a yellow-eyed person could be YY or Yp Both giving yellow.
The carrier would also be a yellow-eyed Yp.

Assuming that the second person in the question is a "pure" yellow, any offspring will have a 50% chance of being a carrier. (The Yp person must give one or other gene, and there are only two)

But "a yellow-eyed person" could also be a Yp.
That would give YY Yp pY pp as the four combinations.
50% carriers as before, (Yp and pY) But surprise, surprise, a 25% chance of a purple eyed person!

NB that's not 50% of the offspring will be carriers, but that each offspring has a 50% chance of being a carrier. There's a definite difference!

Answer 3

If you cross a dominant with a recessive, 100% of the F1 proginey will show the dominant phenotype, but will be carriers for both eye colors.

Answer 4

50%
Parent 1: Yy
Parent 2: YY (assuming it is homozygous, since it isn't stated in the question)

Possible combinations:
YY
Yy
YY
Yy
Therefore 50% of the offspring are carriers.