1. Tardigrade
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  4. The nuclear structure observed by Henkings in 50% of the insect sperm after spermatogenesis was

Q. The nuclear structure observed by Henkings in 50% of the insect sperm after spermatogenesis was

 6018  238 KEAMKEAM 2015Principles of Inheritance and Variation Report Error

Solution:

Henking( 1891) traced a specific nuclear structure all through spermatogenesis in a few insects, and it was also observed by him that 50 percent of the sperm received this structure after spermatogenesis, whereas the other 50 percent sperm did not receive it. Henking gave a name to this structure as the X body.
Further investigations by other scientists ledtotheconclusion that the ‘X body’ of Henking was in fact a chromosome and that is why it was given the name X-chromosome. It was also observed that in a large number of insects the mechanism of sex determination is of the XO type, i.e., all eggs bear an additional X-chromosome besides the other chromosomes (autosomes). On the other hand, some of the sperms bear the X-chromosome whereas some do not. Eggs fertilised by sperm having an X-chromosome become females and, those fertilised by sperms that do not have an X-chromosome become males.