In which of the following organisms is a microlecithal egg (egg with a very small amount of stored food) found?

For normal fertility in males,what percentage of sperms must have normal shape and size,and what percentage of sperms must show vigorous motility?

The structure formed after the release of ova from Graafian follicles and which is secretory in nature,is:

The head of a mammalian sperm is...

Release of sperm from the seminiferous tubules is called

The schematic representation of spermatogenesis is given below. How many chromosomes do $P$,$Q$,and $R$ contain?
$P$ (Spermatogonia) $\rightarrow$ $Q$ (Primary Spermatocyte) $\rightarrow$ $R$ (Spermatid)