A male expresses an X linked recessive trait whenever he inherits one recessive allele because he
- A. has only one X chromosome
- B. has two Y chromosomes
- C. inactivates the normal allele
- D. lacks the gene altogether
Explanation
With no second X to supply a dominant allele, the single recessive allele has nothing to mask it, a state called hemizygosity. Females need two copies of the same allele to show the trait, which is why these conditions are commoner in men.
Related questions
The separation of the two alleles of a gene so that each gamete receives only one of them is Mendel's law of
The F2 phenotypic ratio of a dihybrid cross between two heterozygotes is
To find out whether a tall pea plant is homozygous or heterozygous, it should be crossed with
The genotypic ratio of the F2 generation of a monohybrid cross is
A red flowered four o'clock plant crossed with a white flowered one gives pink flowered offspring. This is an example of