Sperms become non-motile in the vagina in
Less than $60$ minutes
More than $60$ minutes
$120$ minutes
$25-30$ hours
The ratio of the nucleus to cytoplasm at the beginning of cleavage is
Study the flow chart. Name the hormones labelled as $A, B, C, D$ at each stage.
$A \quad B\quad C \quad D$
During gastrulation the dorsal lip of blastopore (1 external sign of gastrulation) appears
How does zona pellucida of ovum help in preventing polyspermy ?
Corpus luteum secretes.....