Kaplan Nursing Entrance Practice Exam

What fusion occurs in the endosperm of flowers?

1. A sperm nucleus fuses with the ovule

2. The sperm nucleus fuses with two polar bodies

3. Two sperm nuclei fuse to form the embryo

4. One sperm nucleus fuses with the stigma

The correct answer is: The sperm nucleus fuses with two polar bodies

In the process of double fertilization characteristic of angiosperms (flowering plants), one of the key events occurs in the endosperm formation. The correct choice involves the fusion of a sperm nucleus with two polar nuclei. This fusion results in the formation of the triploid endosperm, which serves as a nutrient-rich tissue that supports the developing embryo inside the seed. This unique reproductive strategy allows for the efficient nourishment of the embryo as it develops. The endosperm provides essential nutrients, helping to sustain the embryo as it grows and ultimately contributes to the seed's viability and successful germination. The triploid nature of the endosperm is significant since it has a different genetic background than both the embryo and the surrounding maternal tissues. The other scenarios described do not correctly represent the fusion processes that occur in the endosperm. Understanding this specific fusion can aid in grasping the broader concepts of plant reproductive strategies and the significance of endosperm in plant development.