Question 1

Why is a pollen grain called a male gametophyte rather than a male gamete?

Accepted Answer

A pollen grain is a developing male gametophyte because it contains the vegetative or tube cell and, commonly, a generative cell. The generative cell divides to produce the two male gametes, which may begin forming during pollen-tube growth.

Question 2

How does a compatible pollen tube reach the ovule?

Accepted Answer

The pollen grain hydrates and germinates on the receptive stigma. Its tube then grows through stigma and style tissues, commonly along the transmitting tract, toward an ovule and usually enters the embryo sac through the micropyle.

Question 3

What is the role of the filiform apparatus?

Accepted Answer

The filiform apparatus is a specialized region in a synergid at the micropylar end of the embryo sac. It helps attract and guide the pollen tube toward the synergid, into which the tube usually releases its contents.

Question 4

How is the typical embryo sac organized?

Accepted Answer

The embryo sac is seven-celled and eight-nucleate. It has one egg cell, two synergids, three antipodals and one central cell containing two polar nuclei; the two polar nuclei later form the secondary nucleus.

Question 5

Does self-incompatibility mean every self pollen grain is rejected?

Accepted Answer

No. Self-incompatibility is a specific pollen–pistil incompatibility system, not a rule for every flowering plant or every self pollen grain. Where self-incompatibility occurs, rejected pollen may fail to germinate or its tube may fail to grow through the style and reach the ovule.

Pollen–Pistil Interaction 3D — Germination, Guidance & Self-Incompatibility

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