An axial filament in the tail of sperm is modified . . . . . . .

Which of the following is diploid $(2n)$?

Arrange the following cell layers/structures around the female gamete, from outer to inner side :
$A$. Zona pellucida
$B$. Perivitelline space
$C$. Corona radiata
$D$. Plasma membrane of ovum

Ejaculation of human male contains about $200 - 300$ million sperms,of which for normal fertility . . . . . . $\%$ sperms must have normal shape and size and at least . . . . . . $\%$ must show energetic motility.

Which type of division is observed during the second maturation phase of gametogenesis?

When released from the ovary, a human egg contains: