Cleidoic eggs are found in

The human sperms were first seen and discovered by

The blastopore develops into future

Epiboly is the process of

Which of the following labelled parts produces energy for the movement of the tail that facilitate sperm motility essential for fertilisation?

$A$ : The morula passes through the phase of compaction, produces two major type of cells : the peripheral cells and the inner cell mass.
$R$ : The descendants of inner cell mass become the trophoblast cells