Leaves of $Bryophyllum$ fallen on the ground produce new plants. Why?

Offspring formed as a result of sexual reproduction exhibit more variations because

Why does the lining of the uterus become thick and spongy every month?

Where is $DNA$ found in a cell?

Factors responsible for the rapid spread of bread mould on slices of bread are:
$(i)$ Large number of spores
$(ii)$ Availability of moisture and nutrients in bread
$(iii)$ Presence of tubular branched hyphae
$(iv)$ Formation of round-shaped sporangia

What are the benefits of using mechanical barriers during sexual act?