Which elements of the phloem become dead at maturity ?

Options

A. Sieve tube elements
B. Companion cells
C. Sieve cells
D. Phloem fibres

Answer

To answer the question "Which elements of the phloem become dead at maturity?", we can follow these steps:

### Step-by-Step Solution:

1. **Understand Phloem Structure**: Phloem is a complex tissue in plants responsible for the transport of food, particularly sugars. It consists of several components.

2. **Identify Phloem Components**: The main elements of phloem include:
- Sieve tubes
- Companion cells
- Phloem parenchyma
- Phloem fibers

3. **Determine the Function of Each Component**:
- **Sieve tubes**: These are living cells that transport sugars and other organic nutrients.
- **Companion cells**: These are also living cells that assist sieve tubes in their function.
- **Phloem parenchyma**: These cells are living and involved in storage and transport.
- **Phloem fibers**: These provide structural support and strength.

4. **Identify Which Components Are Dead at Maturity**: Among these components, the phloem fibers are the ones that become dead at maturity. They provide tensile strength but do not remain alive like the other phloem elements.

5. **Conclude the Answer**: Therefore, the element of the phloem that becomes dead at maturity is the **phloem fibers**.

### Final Answer:
The elements of the phloem that become dead at maturity are the **phloem fibers**.

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