The number of Barr bodies in a $XXXX$ female is:

When the chromosome number of a given organism has one additional chromosome in one of the homologous pairs,the addition is known as

What is Down's syndrome? Give its symptoms and cause. Why is it that the chances of having a child with Down's syndrome increase if the age of the mother exceeds forty years?

Loss of a $X$ chromosome in a particular cell during its development results in:

Explain the difference between Euploidy and Aneuploidy.

Example for autosomal hyper aneuploidy is