Oct 09
17
Have 2 Bio Questions.. Please Help..?
Posted by adminWhich is a simple, autosomal dominant-recessive trait?
(1) hen-feathered in fowl
(2) hemophilia
(3) red-green color blindness
(4) male pattern baldness
(5) eye color
Which of the following is indicative of females?
(1) XX allosomes
(2) Barr bodies
(3) inactive X chromosome
(4) all of the above
(5) none of the above
If the probability of producing a male offspring is 1/2, what is the probability that the first three offspring will all be males?
(1) 1/2
(2) 1/4
(3) 1/6
(4) 1/8
(5) none of the above
IS 1/8 THE CORRECT ANSWER FOR THIS ONE??
I might consider going with hen-feathered for the first one as it is clearly autosomal inheritance, but with differing expression in males or females due to modifying genes. Technically, this is referred to as a sex-limited trait, with autosomal inheritance. As a caveat, I wouldn’t state this is simple (there are simpler examples that could have been used), but it is as simple as male pattern baldness which is most likely autosomal, but with incomplete penetrance. Hemophilia and red-green colorblindness are both X-linked. Eye color is polygenic, so although it is dominant-recessive, it isn’t simple, but is autosomal. I guess I am getting hung up on the word simple and what that means and whether it means a single gene or if it means there are no complicating factors for expression of the genes. You could pick hen-feathered or eye color, depending on your teacher’s meaning of “simple.”
The second is all of the above.
You are correct on the third, it is 1/8 (1/2 x 1/2 x 1/2).
First one is eye color. The others are X-linked.
Second one is all of the above.
The third is 1/8, so you are correct. (1/2)^3