1. Tardigrade
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  4. Assertion: XX-XY type of sex determination mechanism is an example of male heterogamety. Reason: In birds, male heterogamety is seen as males produce two different types of gametes.

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Q. Assertion: XX-XY type of sex determination mechanism is an example of male heterogamety.
Reason : In birds, male heterogamety is seen as males produce two different types of gametes.

AIIMSAIIMS 2016Principles of Inheritance and Variation

Solution:

Chromosomal or allosomic determination of sex is based on heterogamety or occurence of two types of gametes in one of the two sexes. Male heterogamety is found in allosome complements XX-XY and XX-XO.
In birds and some reptiles both the sexes possess two sex chromosomes but unlike human beings the females contain heteromorphic sex chromosomes (AA + ZW) while the males have homomorphic sex chromosomes (AA + ZZ).