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STD 12 - 4. principal of inheritance and variation — NEET STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceNEETSTD 12 - 4. principal of inheritance and variation4 Marks
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).

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