Fertilization pathway in flowering plants During pollination and fertilization, how does the male gamete nucleus actually reach the egg cell within the ovule?

Introduction / Context:
Angiosperm fertilization involves precise cellular interactions from stigma to ovule. Understanding the role of the pollen tube clarifies how male gametes reach the female gametophyte.

Given Data / Assumptions:

• Pollination places pollen on the stigma.
• Fertilization requires male gamete nuclei to reach the egg cell in the embryo sac.
• The plant provides guided growth mechanisms.

Concept / Approach:
Pollen hydration and germination on the stigma initiate pollen tube growth through the style to the ovary. Two sperm cells are delivered via this tube; one fuses with the egg (zygote), the other with the central cell (endosperm) in double fertilization.

Step-by-Step Solution:

Verification / Alternative check:
Microscopy studies show tube growth and discharge in synergid cells, confirming delivery of sperm nuclei through the pollen tube.

Why Other Options Are Wrong:

• Bee legs/wind/nectar: assist pollination, not the gamete delivery into the embryo sac.
• Diffusion through stigma: gametes do not diffuse; a pollen tube is required.

Common Pitfalls:
Equating pollination (transfer of pollen) with fertilization (fusion of gametes); they are distinct processes.

Final Answer:
The pollen grain germinates a pollen tube; the male nucleus travels down this tube to the egg cell