Q2 of 85 Page 288

What determines the sex of a child?

XX : mother


XY : father


The mother always contributes one X chromosome to the sex of the baby while the father may contribute either an X or Y chromosome. When the father contributes Y chromosome, the baby born is a boy as the set of chromosome he will have would be XY and, if the father contributes X chromosome, the progeny will be a baby girl.

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41

After attending a class lecture on evolution, Katy came home and gathered photographs of all her possible relatives and grandparents. Afterward she made a family tree using those photographs in which she was surprised to see her resemblance to most of her relatives and grandparents.

(i) Why was there resemblance seen by Katy to most of her relatives?


(ii) What are the laws of inheritance? Name them.


(iii) What values are shown by Katy?

 1

According to the evolutionary theory, the formation of a new species is generally due to

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When a breed of cattle with red coats is crossed with the same breed with coats, the offspring all have coats with a mixture of red and white hairs, a condition called roan. If roan cows were crossed with a red- coated bull, the theoretical ratio of the offspring would be

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Which statement is true for a dominant allele?