Question

Double fertilization occurs in: ____.

• A. Gymnocarpous (Gymnosperms)
• B. Angiosperms
• C. Bryophytes
• D. Algae

Hint:

Keep the chromosome ploidy straight: the Zygote is Diploid ($2n$), but the product of triple fusion, the Endosperm, is Triploid ($3n$).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Double fertilization is a complex, unique reproductive mechanism discovered by S.G. Nawaschin, serving as a defining characteristic of flowering plants.

Step 2: Detailed Explanation:
In Angiosperms, the pollen tube releases two male gametes into the embryo sac:
• Syngamy: One male gamete fuses with the egg cell to form a diploid ($2n$) zygote, which eventually develops into the embryo.
• Triple Fusion: The second male gamete fuses with the two polar nuclei (or the secondary nucleus) to form a triploid ($3n$) Primary Endosperm Nucleus (PEN), which develops into nutritive endosperm tissue. Because two types of fusions take place inside the same embryo sac, the event is called double fertilization. Other plant groups like Gymnosperms, Bryophytes, and Algae do not show this phenomenon.

Step 3: Final Answer:
Double fertilization occurs exclusively in Angiosperms.