A) 44 chromosomes
B) 45 chromosomes
C) 47 chromosomes
D) 46 chromosomes
Correct Answer: C
Solution :
Mongolism or Down syndrome or Trisomy 21 was the first chromosomal disorder identified. It is a congenital form of mental retardation due to a chromosome defect, in which there are 3 copies of chromosome number 21, instead of the usual 2 copies, ie, (2n+1). Hence, the mongolic patient possesses 47 chromosomes instead of 46. The affected individual has a short broad face and stanted eyes, short fingers and weak muscles. It is named after the British physician John Down, who first studied it. Turners syndrome (44 + XO) inherits a single X-chromosome instead of two sex-chromosomes, ie, these are monosomics for sex chromosomes. These syndromes are sterile females.
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