The most resistant organic material known which makes up the outemost layer of pollen wall is

Options

A. pectin
B. cellulose
C. sprorpollenin
D. lignin

Answer

**Step-by-Step Solution:**

1. **Understanding Pollen Structure**: Pollen grains are the male gametes of flowering plants and are covered by two layers: the inner layer and the outer layer.

2. **Identifying the Inner Layer**: The inner layer of the pollen wall is known as the "entine." This layer is relatively thin and is composed of substances like pectin and cellulose.

3. **Identifying the Outer Layer**: The outer layer of the pollen grain is much thicker than the inner layer. This outer layer is characterized by the presence of pores, known as germ pores, which facilitate the growth of the pollen tube during fertilization.

4. **Naming the Outer Layer**: The outer layer of the pollen grain is called "exine."

5. **Composition of Exine**: The exine is primarily made up of a highly resistant organic material known as "sporopollenin."

6. **Properties of Sporopollenin**: Sporopollenin is recognized as the most resistant organic material in the living world. It can withstand extreme temperatures and is not easily digested by enzymes, strong acids, or alkalis.

7. **Significance of Sporopollenin**: Due to its durability, pollen grains containing sporopollenin can survive for long periods, making them some of the oldest fossils found.

8. **Final Answer**: Therefore, the most resistant organic material that makes up the outermost layer of the pollen wall is "sporopollenin."

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