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Biology · 2025 · 2 marks
CBSE 2025 · Region 1 · Set 2 · Q17
Study the two different crosses given below: Identify the abnormalities 1 and 2 in the offsprings of given crosses and distinguish between them.
Study the two different crosses given below :
Identify the abnormalities $\displaystyle 1$ and $\displaystyle 2$ in the offsprings of given crosses and distinguish between them.
Marking-scheme solution
$\displaystyle 1$ - Down's Syndrome ($\displaystyle 45$+XX / $\displaystyle 45$+XY) / Trisomy of autosome
$\displaystyle 2$ - Klinefelter's Syndrome ($\displaystyle 44$+XXY)
| Down's syndrome / Trisomy of autosome | Klinefelter's syndrome |
| Trisomy $\displaystyle 21 ^{st}$ chromosome / one extra autosomal chromosome | Presence of an extra sex chromosome / Trisomy of sex chromosome |
| Sterile male or sterile female | Only sterile male |
| Affected individuals are short statured with small round head / furrowed tongue / physical, psychomotor and mental development is retarded | Overall masculine development with feminine development (development of breast) / gynaecomastia / tall statured |
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