Q4 of 32 Page 32

Explain why generally only the male child suffers from colour blindness and not the female?

Colour blindness is the inability of a person to distinguish red, green or both the colours from the other colours. It is caused due to recessive genes which occur on the X chromosome. The colour blindness in women can be expressed only if its genes are present on both the chromosomes but when present only on one chromosome, they become a carrier. Males have only one X chromosome. If there is recessive gene is present on X chromosome. Then the male will suffer from colour-blindness.


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List any three features of garden pea with their dominant and recessive traits.

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Explain the following terms:

(a) Heterozygous


(b) Homozygous


(c) Pedigree chart.