Down syndrome is caused by the presence of an extra copy of chromosome number ....................... .
Q.1 (A)(iii) Down syndrome is caused by the presence of an extra copy of chromosome number ....................... .
A. 13
B. 18
C. 21
D. 23
1 answer
Best answer
Answer: C. 21
Answer: (C) 21
Down syndrome is a chromosomal disorder in which the person has three copies of chromosome 21 instead of two (trisomy 21), so the total number of chromosomes is 47 instead of 46. Such persons show mental retardation, a short stature and a typical round flat face.
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· 27 Oct 2026
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