Which innermost microsporangial wall layer is characterized by dense cytoplasm, polyploid or multinucleate cells, and the secretion of nutrients and sporopollenin precursors for developing microspores?
Answer and explanation
Correct answer: C. Tapetum
1. Epidermis (outermost single protective layer),
2. Endothecium (possesses alpha-cellulose fibrous bands that assist in hygroscopic dehiscence),
3. Middle layers (1 to 3 short-lived ephemeral layers),
4. Tapetum (innermost layer).
2. Endothecium (possesses alpha-cellulose fibrous bands that assist in hygroscopic dehiscence),
3. Middle layers (1 to 3 short-lived ephemeral layers),
4. Tapetum (innermost layer).
- Step 1: An anther microsporangium is enclosed by four concentric wall layers:
- Step 2: The tapetum nourishes developing microspore mother cells and young pollen grains.
- Step 3: Its cells undergo endomitosis, becoming multinucleate or polyploid, and secrete callase, Ubisch bodies, sporopollenin precursors, and pollenkitt.
Answer
Tapetum
Why not the others: 'Endothecium' lies beneath the epidermis and develops fibrous wall thickenings for anther dehiscence; 'Middle layers' are 1-3 layers that degenerate early to provide space; 'Epidermis' is the outermost single-cell protective barrier.
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