Relative morphologies of chromosomes of an individual indicate his/her

Define aneuploidy. How is it different from polyploidy? Describe the individuals having the following chromosomal abnormalities:
$(a)$ Trisomy of $21^{st}$ chromosome
$(b)$ $XXY$
$(c)$ $XO$

The Barr body is observed in

The condition of sex chromosomes in a male child with Down's syndrome will be:

Edward syndrome is on account of .......

Given below are two statements :
Statement $I$ : Down's syndrome is caused by the absence of one of the $X$-chromosomes.
Statement $II$ : Turner's syndrome is caused by the presence of an additional copy of the chromosomes.
In the light of the above statements, choose the correct answer from the options given below :