Question

________ linked diseases are mainly due to recessive genes present on the X-chromosome.

• A. X
• B. x

Answer 1

Answer: (A), (B)

The correct options are
A

X

B

x

X-linked diseases are mainly due to recessive genes present on the X-chromosome. A carrier has a single defective allele. Females have two X-chromosomes and as carriers posses only one defective allele. The other allele on the homologous chromosome is normal, and the normal allele masks the effect of the defective allele, due to which females do not suffer from the disease and are carriers. Females suffer from the disease if both the alleles are defective.