MCQ
In Down's syndrome $(Mongolism)$ each cell has how many chromosomes
- A${21^{st}}$ pair having one less
- B${23^{rd}}$ pair with one less
- C$45$
- ✓$47$
✓
Answer
Correct option: D.
$47$
d
(d) Down’s syndrome is caused by the presence of an extra chromosome number $21$. Thus the egg possesses $24$ chromosomes instead of $23$ and offspring has $47$ chromosomes ($45 + xy$ in male, $45 + xx$ in female).
(d) Down’s syndrome is caused by the presence of an extra chromosome number $21$. Thus the egg possesses $24$ chromosomes instead of $23$ and offspring has $47$ chromosomes ($45 + xy$ in male, $45 + xx$ in female).
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