In humans. eye shape is controlled by a single gene. Almond-shaped eyes are domi
ID: 99701 • Letter: I
Question
In humans. eye shape is controlled by a single gene. Almond-shaped eyes are dominant over rounded eyes. The length of eyelashes is also controlled by a single gene, and long eyelashes are dominant over short eyelashes.
Consider a man that is heterozygous for almond eyes and long eyelashes and a woman with rounded eyes and short eyelashes.
If they have 2 children, what is the probability that the first child looks like dad and the second child looks like mom?
What is the probability that one child will look like dad and one will look like mom, regardless of order?
Enter fractions only in the provid
Explanation / Answer
Almond shaped eyes are dominant - AA
Round eyes- aa
Long eyelashes - BB
short eyelashes -bb
Parents: Heterozygote man for Almond eyes and long eyelashes with a woman homozygous (offcourse, since the trait of the woman can be expressed in homozygous conditions only as the almond is dominant over round) for round eyes and short eyelashes
AaBb X aabb
Gametes that dad will make : AB,Ab, aB, ab
Gametes that mum will make: ab
Cross between the two:
Only one child looks like mum (aabb) and only one kid looks like dad (AaBb).
Probability the first looks like dad and the second looks like mum:
1/4x1/4= 1/16
Probability that one child will look like dad and one will look like mum:
We will use bionomial theorem here:
p= 1/4, q=1/4
P = n!/x!(n-x)! x pxqn-x
where n= total number of events, here which is 4
where x= is the number of events in one category, here which is =1
= 4!/1!(4-1)! X (1/4)1 x (1/4)1
=1/4
AB Ab aB ab ab AaBb Aabb aaBb aabb