An allele that is able to mask the expression of its partner allele is said to be __________.

Recessive X-linked traits 

(a) Are passed from fathers to their sons

(b) Are more likely to be expressed in males

(c) Always affect some aspect of the reproductive system

(d) Are never expressed in females

(e) Cannot be passed from mothers to daughters

Indicate the type of inheritance involved in each of the following situations. 

(c) The trait is expressed more commonly in sons than in daughters. 

Hemophilia A, a condition in which blood does not clot properly, is a recessive trait located on the X chromosome (Xʰ). Suppose that a woman who is heterozygous for this trait (XXʰ) has children with a normal male (XY). What is the probability that the couple will have daughters with hemophilia? What is the probability that the couple will have sons with hemophilia?

Distinguish between the following paired terms: 

(b) heterozygous and homozygous,