The outer layer of pollen grain is thick and made up of complex ,nonbiodegradable substance called as………………….

Options

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

Answer

**Step-by-Step Solution:**

1. **Understanding Pollen Grain Structure**: Pollen grains have a specific structure that includes an outer layer and an inner layer. The outer layer is known for its thickness and durability.

2. **Identifying the Outer Layer**: The outer layer of the pollen grain is referred to as the "Exine." This layer is crucial for protecting the pollen grain.

3. **Composition of Exine**: The Exine is made up of a complex, non-biodegradable substance. The primary component of the Exine is called "Sporopollenin."

4. **Properties of Sporopollenin**: Sporopollenin is one of the most resistant organic materials known. It can withstand extreme conditions, including high temperatures and strong acids and alkalis.

5. **Non-biodegradability**: Due to its unique structure and properties, no enzymes have been found that can degrade Sporopollenin, confirming its non-biodegradable nature.

6. **Conclusion**: Therefore, the correct answer to the question regarding the outer layer of pollen grain is "Sporopollenin."

**Final Answer**: The outer layer of pollen grain is thick and made up of a complex, non-biodegradable substance called **Sporopollenin**.

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