Question

1. what is formed when a sperm cell combines with the polar nuclei during double fertilization?

pollen grain
embryo
endosperm
fertilized egg

Explanation:

In double - fertilization in plants, one sperm cell fuses with the egg cell to form a zygote (fertilized egg) which develops into an embryo. The other sperm cell fuses with the two polar nuclei to form a triploid cell that develops into the endosperm, which provides nourishment for the developing embryo. A pollen grain contains the male gametophyte and is not formed by the fusion of a sperm and polar nuclei.

Answer:

C. endosperm