Question

The pedigree chart below shows the individuals in a family who exhibit a certain trait. Based on the information in the chart, which of the following provides the best evidence that this is a recessive trait?
Key:
Circle—Female
Square—Male
Green—Exhibits trait"

Couple 3–4 in the 2nd generation produced children who do not show the trait.
Couple 1–2 in the 2nd generation produced children who do show the trait.
Couple 3–4 in the 2nd generation produced children who are identical twins.
Couple 1–2 in the 1st generation produced children who do show the trait.

Answer 1

The best evidence that shows that the trait in the pedigree chart is a recessive trait is couple 3-4 in the 2nd generation producing children who do not show the trait.

The father (3) is affected for the trait but the mother is not. However, none of the children is affected. This means that the allele inherited from the mother by the children is able to mask the effects of the affected allele they inherited from their father.

If the allele they inherited from their father is not recessive, definitely the children should have been affected by the trait. Hence, the trait is expressed by homzygous recessive alleles.

More on recessiveness can be found here: brainly.com/question/18075358