Baldness is a dominant trait that is influenced by an individual's sex. A man will become bald if he has the genotype BB or Bb. A man who is bb will not become bald. A woman will have thinning hair, but not become totally bald, if she is BB. A woman will not become bald, or have thinning hair, if she is Bb or bb.
What will be the outcome if a woman who is XXbb produces a child with a man who is XYBb?
a
There is a 75% chance that the child will not become bald.
b
There is a 25% chance that the child will not become bald.
c
There is a 100% chance that the child will become bald.
d
There is a 50% chance that the child will become bald.
The correct answer is d) There is a 50% chance that the child will become bald.
This is because the woman is XXbb, which means she does not carry the baldness trait. The man is XYBb, which means he carries one baldness allele.
When the child is conceived, there is a 50% chance that the child will inherit the baldness allele from the father, resulting in the genotype XBb. This would make the child a carrier of the baldness trait but not bald themselves.
On the other hand, there is a 50% chance that the child will inherit the normal allele from the father, resulting in the genotype Xb. This would mean the child does not carry the baldness trait and will not become bald.