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Questions and Answers
What is the main function of the tapetum in the microsporangium?
Which layers surround a typical microsporangium?
What structural feature distinguishes the anther of angiosperms?
What type of division do cells in the sporogenous tissue undergo to form microspore tetrads?
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Which statement correctly describes the appearance of a microsporangium in a transverse section?
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What is the primary purpose of the outer three wall layers of the microsporangium?
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How many microsporangia are located in a typical angiosperm anther?
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What is the expected ploidy of cells in the microspore tetrad after meiotic division?
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Study Notes
Sexual Reproduction in Flowering Plants
Stamen Structure
- A typical stamen consists of a filament (stalk) and an anther (bilobed structure).
- The filament's proximal end attaches to the flower's thalamus or petal.
- Variation in the number and length of stamens exists across different flower species.
- Observing stamens under a dissecting microscope reveals diversity in size, shape, and anther attachment.
Anther Characteristics
- Angiosperm anthers are bilobed with two thecae (dithecous) in each lobe.
- A longitudinal groove often separates the thecae.
- Anthers are typically tetragonal, containing four microsporangia located at their corners.
- Each microsporangium develops into a pollen sac filled with pollen grains.
Microsporangium Structure
- In transverse sections, microsporangia appear near circular and consist of four wall layers: epidermis, endothecium, middle layers, and tapetum.
- The outer three layers protect the microsporangium and assist in the anther's dehiscence to release pollen.
- The tapetum, the innermost layer, nourishes developing pollen grains with its dense cytoplasm and typically multinucleated cells.
Microsporogenesis Process
- As the anther matures, sporogenous tissue, a compact mass of homogenous cells, occupies the center of each microsporangium.
- The cells undergo meiotic divisions to form microspore tetrads, which are typically haploid (n).
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Description
This quiz focuses on the structure of the stamen, including the filament and anther, as part of the sexual reproduction process in flowering plants. It explores variations in stamens across different species, enhancing your understanding of plant anatomy. Test your knowledge on pollen grains and microsporangia as well.
