_________ is not sex-linked

Explanation

This Biology question is asking which of the given options is not sex-linked. The options are stunted growth, river blindness, haemophilia, and colour blindness. Sex-linked traits are traits that are carried on the sex chromosomes, X and Y. In humans, females have two X chromosomes while males have one X and one Y chromosome. This means that sex-linked traits are more commonly expressed in males as they only have one X chromosome. Out of the given options, the correct answer is river blindness. River blindness is caused by a parasitic worm that is transmitted by the black fly. It is not related to the sex chromosomes and is therefore not a sex-linked trait. Stunted growth, haemophilia, and colour blindness, on the other hand, are all sex-linked traits. Stunted growth can be caused by mutations on the X chromosome, haemophilia is a bleeding disorder caused by a deficiency in clotting factors that are carried on the X chromosome, and colour blindness is caused by mutations in genes on the X chromosome. It is important to understand sex-linked traits as they can affect the inheritance patterns of certain traits and diseases. For more information on sex-linked traits and inheritance patterns, please see the relevant sections of the recommended textbooks.