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Biology · 2025 · 3 marks
CBSE 2025 · Region 6 · Set 2 · Q25
Answer the following questions with respect to the sex determination mechanism in birds: (a) Name the type of heterogamety observed in most birds.…
Answer the following questions with respect to the sex determination mechanism in birds :
(a)
Name the type of heterogamety observed in most birds.
(b)
If the birds have $\displaystyle 18$ pairs of autosomal chromosomes and a pair of sex chromosomes, fill in the blanks (i), (ii), (iii) and (iv) in the table given below. (Use symbols Z and W for sex chromosomes.)
| Total number of autosomes (in a diploid cell) | Type of sex chromosomes (in a diploid cell) | |
| Male bird | (i) $\displaystyle \_\_\_\_$ | (ii) $\displaystyle \_\_\_\_$ |
| Female bird | (iii) $\displaystyle \_\_\_\_$ | (iv) $\displaystyle \_\_\_\_$ |
Marking-scheme solution
(a)
female heterogamety/ ZW
(b)(i)
Male bird-$\displaystyle 36$
(ii)
ZZ
(iii)
Female bird -$\displaystyle 36$
(iv)
ZW
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