A student wants to determine how likely an autosomal dominant trait (X/x) is to be passed on.

A father does not have the trait (x), but the mother does (Xx). What will the Punnett square look like? (1 point)
• 50% Xx; 50% xx.
• 75% Xx; 25% XX
• 25% Xx; 75% xx.
• 50% XX; 50% Xx

1 answer

To determine the likelihood of the autosomal dominant trait being passed on from the given genotypes of the parents, we can set up a Punnett square.

The father is homozygous recessive (genotype xx), and the mother is heterozygous (genotype Xx).

Here is how the Punnett square would look:

          X        x
       ----------------
    x |    Xx     |   xx   |
       ----------------
    x |    Xx     |   xx   |
       ----------------

From this Punnett square, we can see that:

  • Two out of the four boxes (50%) will be Xx (inheriting the dominant trait).
  • Two out of the four boxes (50%) will be xx (inheriting the recessive trait).

So the correct answer is:

50% Xx; 50% xx.