Question

Define Double Fertilization and explain its significance in flowering plants.

Hint:

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

Answer 1

Concept: Double fertilization is a unique characteristic of angiosperms (flowering plants). It involves two fertilization events occurring within the embryo sac of the ovule, leading to the formation of both the embryo and the endosperm.
Step 1:Definition of Double Fertilization Double fertilization is the process in which two male gametes participate in fertilization inside the embryo sac.

• One male gamete fuses with the egg cell to form the zygote.
• The second male gamete fuses with the two polar nuclei to form the endosperm.

Step 2:Fertilization Events

• Syngamy: \[ \text{Male gamete + \text{Egg cell \rightarrow \text{Zygote \]
• Triple Fusion: \[ \text{Male gamete + \text{Two polar nuclei \rightarrow \text{Endosperm \]

Since two fertilization events occur, the process is called double fertilization.
Step 3:Significance of Double Fertilization

• It leads to the formation of the zygote, which develops into the embryo.
• It produces the endosperm, which provides nourishment to the developing embryo.
• It ensures efficient use of nutrients by forming endosperm only after fertilization.
• It is an important feature that distinguishes flowering plants from other plant groups.