Question

What is the function of Tapetum?

• A. Provides nourishment to pollen grains
• B. Protects the ovule
• C. Helps in fertilization
• D. Produces pollen grains

Hint:

The tapetum is easily recognized in histological sections by its multinucleate cells and dense cytoplasm, reflecting its high metabolic activity in nourishing pollen grains.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks for the physiological function of the tapetum layer in the anther of a flower.
This is a core topic in the reproductive anatomy of angiosperms.

Step 2: Key Formula or Approach:
We examine the structural layers of a microsporangium (anther wall) from the outside in:
Epidermis $\rightarrow$ Endothecium $\rightarrow$ Middle layers $\rightarrow$ Tapetum.
We identify the function of the innermost layer, which surrounds the sporogenous tissue.

Step 3: Detailed Explanation:

• The tapetum is the innermost cellular layer of the microsporangium wall.

• The cells of the tapetum are characterized by dense cytoplasm and are generally multinucleate (due to endomitosis).

• The primary function of the tapetum is to provide nourishment to the developing microspores (pollen grains).

• In addition to nourishment, the tapetum plays several other critical roles:
1. It synthesizes and secretes the enzyme callase, which breaks the callose wall holding the pollen tetrad together.
2. It produces Ubisch bodies, which contribute to the synthesis of sporopollenin, the extremely resistant organic substance forming the outer wall (exine) of pollen grains.
3. In insect-pollinated species, it contributes to the formation of a sticky, lipid-rich layer called pollenkitt on the surface of pollen grains.

• The outer three layers (epidermis, endothecium, and middle layers) primarily serve protective roles and help in the dehiscence of the anther to release pollen grains.


Step 4: Final Answer:
Thus, the primary and well-established function of the tapetum is to provide nourishment to the developing pollen grains.