WAEC SSCE - Biology - 2008 (Objective)

Question 1 Report

Which of the following diseases is commonly observed in human males and is sex-linked?

Beriberi

Down’s syndrome

Sickle-cell anaemia

colour blindness

Answer Details

Color blindness is commonly observed in human males and is sex-linked. Color blindness is a genetic disorder that affects how people see color. It is caused by an abnormality in the genes that encode for the photopigments in the cone cells of the retina. Because these genes are located on the X chromosome, which is one of the two sex chromosomes, the disorder is sex-linked. Males only have one X chromosome, so if they inherit a color blindness gene on that chromosome, they will have the disorder. Females, on the other hand, have two X chromosomes, so they are less likely to have the disorder, as they need to inherit the gene on both X chromosomes to be affected.

Read lesson note on Linkage, Sex Determination And Sex Linked Characters (WAEC)






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