A normal-visioned man whose father was colour blind, marries a woman whose father was also colourblind. They…

A normal-visioned man whose father was colour blind, marries a woman whose father was also colourblind. They have their first child as a daughter. What are the chances that this child would be colourblind?
  1. $100 \%$
  2. $0 \%$
  3. $25 \%$
  4. $50 \%$

Solution

Colour blindness is an X-linked disease. So, woman whose father was colourblind will be carrier for the disease. So, possibility of a colourblind daughter (i.e., $X^{\mathrm{c}} \mathrm{X}^{\mathrm{c}}$ in $\mathrm{F}_1$ generation is $0 \%$.

Asked in: NEET 2012 (Screening)

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