What is the nature of male gametes in angiosperms?

What is correct for water hyacinth $(Eichhornia \text{ } crassipes)$?
$1.$ Aquatic weed
$2.$ Terrestrial weed
$3.$ Threat to native species
$4.$ Useful to native species
$5.$ Asexual reproduction

Which of the following statement$(s)$ is/are correct for cleistogamous flowers?
$(a)$ They have exposed anthers and stigma
$(b)$ They produce assured seed set
$(c)$ They need pollinators for pollination
$(d)$ Variations in traits are not seen in next generation

If a stem has $2n = 10$ chromosomes,find out the number of chromosomes in:
$A$ - Endosperm
$B$ - Egg cell
$C$ - Polar nuclei

In which animal do haploid cells divide mitotically to produce gametes?

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