In a homozygous pea plant, axial flowers (A) are dominant over terminal flowers (a).
Name two genetic disorders commonly seen in human males.
Topic: Sex-linked disorders in males
Answer
- COLOUR BLINDNESS — the inability to distinguish certain colours, usually red and green.
- HAEMOPHILIA — a disorder in which the blood fails to clot normally.
Both are SEX-LINKED RECESSIVE disorders, carried on the X chromosome — which is exactly why the question says "commonly seen in human MALES".
THE REASON FOR THE ASYMMETRY: a male is XY, so a SINGLE defective X is enough to produce the disorder — the Y carries no corresponding allele to mask it. A female is XX and would need a defective X from BOTH parents, which is very rare. Women are therefore usually CARRIERS rather than sufferers.
That asymmetry is the defining feature of sex-linked inheritance, and it is what examiners test.
Note that ALBINISM is also a genetic disorder but is AUTOSOMAL recessive, affecting both sexes equally — so it would be a wrong answer here.