Which unaffected individuals could POSSIBLY BE EITHER HOMOZY

Which unaffected individuals could POSSIBLY BE EITHER HOMOZYGOUS or HETEROZYGOUS A_? Select all that apply.

1-1, 1-2, 1-4, 2-1, 2-4, 2-8, 3-1, 3-5, 4-1, 4-7

I have narrowed it down to what I think is the correct answer,

2-8, and 3-1 are the only ones that can EITHER BE homozygous AA or heterozygous A_, due to the filled in squares/circles representing a recessive trait inheritance.

I am a little skeptical about 3-5, as none of the offspring have the recessive trait, despite a parent having it, meaning if it were Aa and aa then one of the progeny would more than likely have aa at least once, whereas if AA and aa, none would have the trait as shown.

Please double check my answer,

letting me know if my reasoning was faulty.

Thanks in advance.

Max

IV OHTO 1 3 5 6 7 Pearson Education, Inc.

Solution

yes your answer is right as 2-8 can be homozygous due to the presence of a recessive trait which is usually found when two genes are similar like AA or BB which happens in this case shown by the filled circle.

3-1 is heterozygous because it has one fixed gene and another gene can vary as shown by A_ .This is again shown by circles in the figure emntioned above.