Which of the following statements about sex-linked characters is not true?

Analyze the question: We need the statement that is NOT true about sex-linked characters.

Concept: Sex-linked characters are controlled by genes on the sex chromosomes, mostly the X chromosome (e.g., colour blindness, haemophilia).

• Females are XX, so they can be carriers (heterozygous, X^N X^n) with one normal and one recessive allele.
• Males are XY, with only one X. If the X carries the recessive allele, the male shows the condition. He has no second allele to mask it.

Checking each option:

• A. Usually borne on the X chromosome. True. Most sex-linked genes are on the X chromosome.
• B. More common in males. True. Males need only one recessive allele to show the trait, while females need two.
• C. Males are usually carriers. False. A carrier has the recessive allele but does not show the trait. Since males have only one X, any male with the recessive allele expresses it, so males are affected, not carriers. Carriers are typically females.
• D. Not usually carried on the Y chromosome. True. The Y chromosome is small and carries very few genes, so sex-linked traits are mostly not found on it.

Answer: The statement that is not true is C.

Tip: Remember "Females carry, males show." For X-linked recessive traits, a male is either affected or normal, never a carrier. When a question asks for the statement that is "not true", test each option and eliminate those you know are correct.