What is haploid cell?

What is the haploid cell which develops into the embryo sac?

Zygote is a haploid cell.

What do you mean by haploid cell ?

What do you know about haploid cell?

Which haploid cell forms embryo sac?

In which phase of cell cycle the amout of DNA in a diploid cell become four times as compared to a haploid cell?

In which phase of cell cycle the amout of DNA in a diploid cell become four times as compared to a haploid cell?