By deep freezing,it is possible to preserve embryos at which stage?

Identify the haploid and diploid structures from the following list:
$I$ - Megaspore mother cell
$II$ - Microspore mother cell
$III$ - Egg cell
$IV$ - Male gamete
$V$ - Synergid
$VI$ - Embryo
$VII$ - Antipodal cell
$VIII$ - Zygote
$IX$ - Megaspore
$X$ - Microspore
Select the correct grouping for Haploid and Diploid structures.

The cell that undergoes meiosis is called:

Bisexual flowers which never open,demonstrate

Study the following statements and choose the correct option.
$I-$ Tapetum nourishes the developing pollen grains.
$II-$ Hilum represents the junction between ovule and funicle.
$III-$ In aquatic plants such as water hyacinth and water lily,pollination is by water.
$IV-$ The primary endosperm nucleus is triploid.

In plant $A$,$2n = 12$ and in plant $B$,$2n = 16$. Then the ploidy number (total chromosome number) of the hybrid plant resulting from cross-breeding is: