Which of the following tissue is mainly composed of dead cells?

Options

A. collenchyma
B. xylem
C. phloem
D. epidermis

Answer

To determine which of the following tissues is mainly composed of dead cells, we will analyze each option provided: colenchyma, xylem, phloem, and epidermis.

1. **Colenchyma**:
- Colenchyma is a type of plant tissue that consists of living cells. These cells are elongated and provide support and flexibility to young plant stems and leaves. Therefore, colenchyma is not composed of dead cells.

2. **Xylem**:
- Xylem is a vascular tissue responsible for the transport of water and minerals from the roots to the rest of the plant. It is primarily made up of two types of cells: tracheids and vessel elements, which are dead at maturity. Additionally, xylem contains fibers, which are also dead cells. Thus, xylem is mainly composed of dead cells.

3. **Phloem**:
- Phloem is another type of vascular tissue, but it is responsible for transporting food (sugars) produced in the leaves to other parts of the plant. Phloem consists of living cells, such as sieve elements and companion cells. Therefore, phloem is not composed of dead cells.

4. **Epidermis**:
- The epidermis is the outermost layer of cells covering the plant. It is primarily composed of living cells that serve protective functions. Thus, the epidermis is not made up of dead cells.

Based on this analysis, the tissue that is mainly composed of dead cells is **xylem**.