A student cuts a young anther across and draws what she sees…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A student cuts a young anther across and draws what she sees. There are four round sacs near the four corners and a vascular bundle in the middle. In each sac, a ring of cells with dense cytoplasm surrounds a core of small cells that look alike.
- What are the four round sacs called?
- Name the ring of cells with dense cytoplasm, and say what it does.
- Name the core, and say what its cells can become.
- Which layer lies just outside the ring?
Need a reminder? The key ideaShow
A flower has four whorls: calyx, corolla, androecium and gynoecium. A stamen has a filament and an anther. A typical anther is bilobed, with two microsporangia in each lobe, so it has four. The wall of a microsporangium has four layers: epidermis, endothecium, middle layers and tapetum. The sporogenous tissue lies in the centre.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. A young anther in cross section.
Plan. Name each structure from its place and its look.
Step 1. The sacs. They are the four microsporangia, also called pollen sacs.
Step 2. The ring. It is the tapetum, the innermost wall layer. Its cells have dense cytoplasm and usually more than one nucleus. It feeds the developing pollen grains.
Step 3. The core. It is the sporogenous tissue. Each cell can become a pollen mother cell.
Step 4. Outside the ring. The middle layers. After them come the endothecium and the epidermis.
Answer: microsporangia; tapetum, feeds the pollen; sporogenous tissue, can become pollen mother cells; middle layers.
Watch out. The tapetum is a wall layer. The sporogenous tissue is the centre and is not part of the wall.
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