Question

Describe the process of Double Fertilization in flowering plants.

Hint:

In flowering plants:
{First fusion → Zygote (embryo)}
{Second fusion → Endosperm (nutrition for embryo)}

Answer 1

Concept: Double fertilization is a unique feature of angiosperms (flowering plants). In this process, two fertilization events occur within the embryo sac of the ovule.
Step 1:Pollination and Pollen Tube Formation After pollination, the pollen grain lands on the stigma and germinates to form a pollen tube. This tube grows through the style and reaches the ovule in the ovary, carrying two male gametes.
Step 2:First Fertilization (Syngamy) One male gamete fuses with the egg cell present in the embryo sac to form a zygote. \[ \text{Male gamete + \text{Egg cell \rightarrow \text{Zygote \] The zygote later develops into the embryo.
Step 3:Second Fertilization (Triple Fusion) The second male gamete fuses with the two polar nuclei present in the central cell of the embryo sac. \[ \text{Male gamete + \text{Two polar nuclei \rightarrow \text{Endosperm \] This forms the endosperm, which provides nourishment to the developing embryo.
Step 4:Meaning of Double Fertilization Since two fertilization events occur in the same embryo sac—syngamy and triple fusion—the process is called double fertilization.