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Questions and Answers
What is the primary function of the tube nucleus during fertilization?
What is the primary function of the tube nucleus during fertilization?
In angiosperms, what happens during the process of double fertilization?
In angiosperms, what happens during the process of double fertilization?
What do the integuments become after the fertilization process?
What do the integuments become after the fertilization process?
In gymnosperms, what characterizes the process of fertilization compared to angiosperms?
In gymnosperms, what characterizes the process of fertilization compared to angiosperms?
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What is the ploidy level of the endosperm formed during angiosperm fertilization?
What is the ploidy level of the endosperm formed during angiosperm fertilization?
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What role do synergid cells play in the fertilization process?
What role do synergid cells play in the fertilization process?
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What chemical function do synergids perform related to the pollen tube?
What chemical function do synergids perform related to the pollen tube?
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What happens to the synergid cell after the release of the sperm cells?
What happens to the synergid cell after the release of the sperm cells?
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How does the central cell influence synergid function?
How does the central cell influence synergid function?
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What additional role does the second sperm cell play after fertilization?
What additional role does the second sperm cell play after fertilization?
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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.
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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.
