Mental retardation in man, associated with sex chromosomal abnormality is usually due to
Reduction in $X$ complement
Increase in $X$ complement
Moderate increase in $Y$ complement
Large increase in $Y$ complement
If the number of chromosomes in most body cells of a mammal is $40$, the cells in the seminiferous tubule will have
The character that is expressed in the $F_{1}$-generation is called the
When different alleles of the same gene are present on an individual, the individual is a
Lathyrus odoratus is an example of which of the following genes
Barr bodies are