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NEETZoologyPrinciples of Inheritance and Variation

In an unknown insect species, spermatogenesis produces two types of sperms in equal proportions: one containing 11 chromosomes and the other containing 12 chromosomes. Oogenesis, however, produces only one type of ovum containing 12 chromosomes. Identify the sex determination system and a representative organism for this pattern.

Options

  1. AXX-XO type, Grasshopper
  2. BXX-XY type, Drosophila
  3. CHaplo-diploid type, Honeybee
  4. DZZ-ZW type, Bird

Correct answer

A. XX-XO type, Grasshopper

Step-by-step solution

The production of two types of sperms with unequal chromosome numbers ( 11 and 12 ) indicates male heterogamety where one sex chromosome is absent in half of the male gametes. This is characteristic of the XX-XO type of sex determination. In this system, males possess autosomes and only one X chromosome (XO). Here, the male has 22 autosomes and one X chromosome (total 23 ), producing sperms with 11 chromosomes ( 11 autosomes + no sex chromosome) and 12 chromosomes ( 11 autosomes + one X chromosome). The female prod

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