Name the plants which exhibit unusual flowering phenomena.

Which one of the following statements is correct?

In multicellular organisms, life begins with a .......... .

In the gametophytic phase,which of the following occurs?

Pollen allergy is caused by pollens of

Choose the correct options for the following statements:
$1$. Autogamy is genetically xenogamy.
$2$. Pollination occurs by air in grass.
$3$. Placenta is arranged in the inner wall of the ovary.
$4$. It is possible to store pollen grains in liquid nitrogen at $-196^oC$.