question_answer

(i) Both grasshopper and cockroach show the phenomenon of male heterogamety. Explain.

(ii) Define female heterogamety with the help of examples.

Answer:

(i) Both the grasshopper and cockroach show male heterogamety, i.e. the males produce two types of gametes.

Males have only one X-chromosome and produce two types of sperms besides autosomes and females have a pair of X-chromosomes and produce homogametic eggs. Eggs fertilised by sperms having an X-chromosome become females and those fertilised by sperms that do not have X-chromosome become males.

(ii) Female heterogamety is shown by female fowls as they have ZW sex chromosomes. The 50% ova contain Z-chromosomes and other 50% ova have W-chromosomes. Hence, they also produce two types of female gametes.