In which of the following pairs of plant structures are haploid chromosomes found?

Which of the following plant families has $polysiphonous$ pollen grains?

For a gene, if $AA = \text{male plant}$ and $BB = \text{female plant}$, find out the genotype of the endosperm and the embryo.

Is the presence of a large number of chromosomes in an organism a hindrance to sexual reproduction? Justify your answer by giving suitable reasons.

Statement $X$: In gymnosperms,the endosperm is formed before fertilization.
Statement $Y$: In angiosperms,double fertilization is observed.

Select the correct option for the following statements:
$(i)$ In the embryo sac of angiosperms,the synergids and antipodals degenerate / do not degenerate after fertilization.
$(ii)$ In the leaves of dicotyledonous plants,parallel / reticulate venation is observed.