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Biology · 2023 · 4 marks
CBSE 2023 · Region 3 · Set 2 · Q30
The following pedigree chart shows the inheritance of a genetic disorder up to three generations of a family. Observe the chart and answer the…
The following pedigree chart shows the inheritance of a genetic disorder up to three generations of a family. Observe the chart and answer the questions that follow. Generation I Generation II
(i)
Is the disease sex-linked or autosomal as per the chart ? Give reasons in support of your answer.
(ii)
Is it a recessive or a dominant disorder?
(iii)
Write the genotypes of the individuals 'C', 'D' and 'H'.
(iv)
(a)
If the female 'D' marries a normal man, what will be the probability of their daughter being a sufferer of this disease ?
OR
(b)
If the mother 'B' is a carrier of the disease, what will be the probability of their daughter being a sufferer of this disease ?
Marking-scheme solution
(i) •Sex linked disorder
-More males are affected in the family as males have only one X chromosome which if affected expresses
(ii) Recessive disorder
(iii) C -XX \(\displaystyle { }^{\mathrm{c}}\); D- XX \(\displaystyle { }^{\mathrm{c}}\); H- \(\displaystyle \mathrm{XX}^{\mathrm{c}}\)
' \(\displaystyle \mathrm{c}\) ' is affected allele, accept other symbols used for the same
(iv)
(a)
Probability $\displaystyle 0$%
OR
(b)
Probability-$\displaystyle 50$%
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