(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.
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