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Heart wood of most of the woody tress, ...

Heart wood of most of the woody tress, fails to conduct sap due to the obstruction by ?

A

Excess secondary wall deposition

B

Storing a variety of material by tyloses

C

Deposition of reserved food material

D

Ray parenchyma

Text Solution

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The correct Answer is:
### Step-by-Step Solution: 1. **Understanding Heartwood**: Heartwood is the central, non-living part of a tree trunk that provides structural support. It is typically darker and denser than the outer layers of the tree. 2. **Function of Heartwood**: Unlike sapwood, which is responsible for the conduction of water and nutrients, heartwood does not conduct sap. This is an important aspect of its role in the tree's anatomy. 3. **Identifying the Obstruction**: The question asks what causes the heartwood to fail in conducting sap. The main reason for this obstruction is the presence of tyloses. 4. **What are Tyloses?**: Tyloses are outgrowths that occur in the parenchyma cells of the xylem vessels. They form as a response to stress conditions such as drought or infection. 5. **Formation of Tyloses**: When a plant is under stress, these outgrowths can develop from the sides of the parenchyma cells and extend into the xylem vessels. This leads to a blockage that prevents the flow of sap. 6. **Significance of Tyloses**: The formation of tyloses serves a protective function. By blocking the xylem vessels, they help to prevent further damage to the plant by stopping the spread of pathogens and reducing water loss. 7. **Conclusion**: Therefore, the heartwood of most woody trees fails to conduct sap due to the obstruction caused by tyloses. ### Final Answer: The heartwood of most woody trees fails to conduct sap due to the obstruction by **tyloses**. ---
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