Traits such as white eyes versus red eyes in fruit flies or

Traits such as white eyes versus red eyes in fruit flies or color-blind versus normal vision in humans are more commonly seen in males than in females. When this type of inheritance pattern emerges, it is a good indication that:

a. the trait is caused by a recessive X-linked gene

b. the trait is cause by a dominant X-linked gene

c. that trait is caused by a chromosomal aberration

d. the trait is caused by a autosomal recessive trait

e. the trait is molded by the environment

Solution

The most appropriate choice is option a, i.e. the trait is caused by a recessive X-linked gene.

Males have one copy of the X chromosome and one copy of the Y chromosome; therefore, the trait is manifested even though it is recessive. Hence, it is common in males. Females, having two copies of X chromosome, do not suffer until they are homozygous for the condition, and are usually carriers of the condition.