Question

Given your knowledge about genetics and heredity, answer the following question about color-blindness.A woman gives birth to a set of fraternal twins: a girl and a boy. She also passes on a color-blindness gene. Which of the children is more likely to be color-blind?(1 point)Responsesthe girl is more likely to be color-blind from birththe girl is more likely to be color-blind from birththe boy is more likely to be color-blind from birththe boy is more likely to be color-blind from birththe girl will never be color-blind because the gene came from her motherthe girl will never be color-blind because the gene came from her motherthe boy will never be color-blind because the gene came from his mother

Answer 1

Color blindness is typically an X-linked recessive trait, meaning it is carried on the X chromosome. A woman has two X chromosomes (XX), while a man has one X chromosome and one Y chromosome (XY).

If the woman passes on a color-blindness allele (which we can represent as "c"), the scenario is as follows:

1. The girl (XX) could either inherit the normal X chromosome (X) or the color-blindness X chromosome (Xc) from her mother, and she would inherit a normal X from her father. She would only be color-blind if she inherits the color-blind X chromosome from both parents (thus, XcXc), which is not possible in this case since her father does not carry the color-blindness gene. Therefore, the girl can be a carrier (XcX) but not color-blind.

2. The boy (XY) inherits his X chromosome from his mother and his Y chromosome from his father. Thus, if he inherits the color-blind X chromosome (Xc) from his mother, he will be color-blind (XcY).

Given this genetic relationship, the boy is more likely to be color-blind if he inherits the color-blind allele from his mother.

So the correct response is: **the boy is more likely to be color-blind from birth.**