Plant Biology Fertilization Overview

Questions and Answers

What is the primary function of the tube nucleus during fertilization?

To provide nutrients to the pollen tube

To guide the pollen tube (correct)

To form the seed coat

To fuse with female egg cells

In angiosperms, what happens during the process of double fertilization?

The female gamete splits and fuses with both generative nuclei

One generative nucleus fuses with the egg cell and the other with the central cell (correct)

Both generative nuclei fuse with egg cells

Only one of the generative nuclei fuses with the egg cell

What do the integuments become after the fertilization process?

The seed coat (correct)

The polar nuclei

The pollen grains

The embryonic structures

In gymnosperms, what characterizes the process of fertilization compared to angiosperms?

Only a single fertilization event occurs between sperm and egg cells Signup and view all the answers

What is the ploidy level of the endosperm formed during angiosperm fertilization?

3n Signup and view all the answers

What role do synergid cells play in the fertilization process?

They attract and guide male nuclei to the egg cell. Signup and view all the answers

What chemical function do synergids perform related to the pollen tube?

Attract the pollen tube to the micropyle. Signup and view all the answers

What happens to the synergid cell after the release of the sperm cells?

It degenerates to allow sperm cell access to the egg cell. Signup and view all the answers

How does the central cell influence synergid function?

It signals for the release of chemical attractants. Signup and view all the answers

What additional role does the second sperm cell play after fertilization?

It migrates to the central cell. Signup and view all the answers

Study Notes

Pollen Tube and Fertilization

The tube nucleus directs the growth of the pollen tube toward the ovule.
Generative nuclei are released into the embryo sac after the pollen tube penetrates the micropyle.

Micropyle and Integuments

Micropyle serves as the natural opening that facilitates pollen tube entry into the ovule.
Integuments consist of two protective layers that form between the nucellus and the embryo sac, ultimately developing into the seed coat.

Fertilization Process

Fertilization involves the fusion of haploid male (1n) and female (1n) gametes, occurring inside the ovule.
In gymnosperms, fertilization is straightforward, involving one sperm nucleus fusing with the egg cell.
Angiosperms experience double fertilization:
- One generative nucleus fuses with the egg cell to create a diploid zygote (2n).
- The other generative nucleus fuses with the two polar nuclei in the central cell, resulting in a triploid endosperm (3n) that nourishes the developing embryo.

Synergid Cells in Plant Fertilization

Female synergid cells are crucial for fertilization as they are located adjacent to the egg cell.
Their primary role is to attract and guide male nuclei (sperm cells) towards the egg cell.
Synergids produce a chemical that directs the pollen tube to the micropyle, the opening through which fertilization occurs.
This chemical also halts the growth of the pollen tube, ensuring timely sperm cell release into the ovule.
Central cells within the ovule signal synergids to release the attractant, enhancing communication between reproductive cells.
Following the release of sperm cells, synergid cells degenerate, allowing sperm cells unimpeded access to the egg cell for fertilization.
One of the sperm cells fuses with the egg cell, while the second sperm cell migrates to the central cell, participating in the formation of endosperm.

Description

This quiz covers key concepts related to fertilization in plants, focusing on the role of the tube nucleus and generative nuclei during pollen tube guidance. It also explores the micropyle's significance and the integuments' development into the seed coat. Test your understanding of these fundamental processes.