Wednesday, July 29, 2009

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

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



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

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.



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

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.



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

1.)50%



2.)A,AB,B,O



3.)25%

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