Question

What do you understand by sex-linked inheritance? Explain it with any one example.

Hint:

Sex-linked traits are more commonly expressed in males due to their single X chromosome.

Answer 1

Step 1: Definition of Sex-Linked Inheritance.
Sex-linked inheritance refers to the pattern of inheritance for genes located on the sex chromosomes (X or Y). In humans, the X chromosome carries a larger number of genes compared to the Y chromosome. Traits controlled by genes on the X chromosome exhibit different inheritance patterns based on the sex of the offspring.
Step 2: Explanation of the Inheritance Pattern.
In males, who have only one X chromosome (XY), a recessive gene on the X chromosome will always be expressed because there is no second X chromosome to mask its effect. In females, who have two X chromosomes (XX), a recessive gene on one X chromosome may be masked by a dominant allele on the other X chromosome. This leads to a different pattern of inheritance in males and females.
Step 3: Example of Sex-Linked Inheritance.
An example of sex-linked inheritance is hemophilia, a genetic disorder where blood doesn't clot properly. The gene for hemophilia is located on the X chromosome. Males with the recessive allele for hemophilia on their single X chromosome will express the disease, while females need two copies of the recessive allele (one on each X chromosome) to express the disease.
Final Answer: \[ \boxed{\text{Sex-linked inheritance refers to traits controlled by genes on the sex chromosomes, with hemophilia being an example.}} \]