Question

Given below are two statements:
Statement (I): Double fertilization involves the fusion of two sperm cells with two egg cells.
Statement (II): In double fertilization, one sperm cell fuses with the egg cell, while the other sperm cell fuses with the two polar nuclei.
In light of the above statements, choose the most appropriate answer from the options given below.

• A. Both Statement (I) and Statement (II) are true.
• B. Both Statement (I) and Statement (II) are false.
• C. Statement (I) is true but Statement (II) is false.
• D. Statement (I) is false but Statement (II) is true.

Hint:

Remember the simple arithmetic of double fertilization:
- Syngamy: 1 Sperm (\(n\)) + 1 Egg (\(n\)) \(\rightarrow\) Zygote (\(2n\))
- Triple Fusion: 1 Sperm (\(n\)) + 2 Polar Nuclei (\(2n\)) \(\rightarrow\) Endosperm (\(3n\))
Only one egg cell is involved.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Double fertilization is a unique and defining reproductive process in angiosperms (flowering plants).
It involves two distinct fertilization events occurring within a single embryo sac.

Step 2: Detailed Explanation:
Let us analyze both statements:
- Statement (I): Angiosperm pollen grains produce two male gametes (sperm cells).
However, the embryo sac contains only one female gamete (egg cell).
Therefore, the two sperm cells do not fuse with two separate egg cells.
This makes Statement (I) false.
- Statement (II): During double fertilization:
1. The first sperm cell (\(n\)) fuses with the egg cell (\(n\)) to form a diploid zygote (\(2n\)), which eventually develops into the embryo.
2. The second sperm cell (\(n\)) migrates to the center of the embryo sac and fuses with the two polar nuclei (\(n + n\)) within the central cell.
This triple fusion event forms a triploid (\(3n\)) primary endosperm nucleus (PEN), which develops into the endosperm to nourish the growing embryo.
This confirms that Statement (II) is true.
Thus, Statement (I) is false and Statement (II) is true, matching Option (D).

Step 3: Final Answer:
Statement (I) is false but Statement (II) is true.