Any Biology geeks? I have some questions for you guys!?

Question

Question 1 text Short hair is dominant over long hair in dogs. If a short-haired dog whose mother is long-haired is crossed with a long-haired dog, what proportion of the offspring will be short-haired?

25%
50%
75%
100%
Impossible to tell


Question 2 text If a man of blood group AB marries a woman of blood group A whose father was O, what phenotypes could their children be?

A only
A, AB, B and O
AB only
A, AB and B
O only


Question 3 text Red-green colorblindness is an X-linked recessive trait. A woman who has a colorblind mother and a father with normal vision has a son with a man with normal vision. What is the chance that the son is colorblind?

100%
75%
50%
25%
Impossible to determine

Answer 1

Question 1. Since the short-haired dog had a mother that is long-haired, then the dog must be heterozygous or Ss. Crossing this dog with a long-haired dog ss the possible offspring combination is Ss and ss or 50% heterozygous and 50% homozygous recessive.

Question 2. A man that has AB blood has the alleles for A and B blood type. The woman has A blood but has a father with O. This would make her blood type alleles A and O. So, the possiblities for the children are A (A from dad, A from mom), AB (A from mom, B from dad) or B (B from dad, O from mom).

Question 3. Since colorblindness is X-linked and the mother is colorblind, that means that both of her X chromosomes contain the colorblindness alleles. Since the son gets his X chromosome from his mom, then there is a 100% chance that the son will be colorblind.

Hope these help.

Answer 2

Come now...genetics is easy.
1. 50% Ss and ss are your parents...Punnett square shows the outcome.
2. A, AB, and B...O is recessive, so it won't show up unless you have OO
3. 50%...she has one X for colorblindness and one normal one...so it's a tossup.

Answer 3

1.)50%

2.)A,AB,B,O

3.)25%