Which of the following cells is usually dead and without a protoplasm?

Options

A. Parenchyma
B. Sclerenchyma
C. Aerenchyma
D. Collenchyma

Answer

To determine which cell type is usually dead and without protoplasm, we can analyze the options provided:

1. **Parenchyma**:
- Parenchyma cells are living cells that are involved in various functions such as photosynthesis, storage, and secretion. They contain protoplasm and are not dead.

2. **Sclerenchyma**:
- Sclerenchyma cells are characterized by their thick, lignified cell walls. These cells are usually dead at maturity and lack protoplasm. They provide structural support to the plant.

3. **Arenchyma**:
- Arenchyma is a type of parenchyma found in aquatic plants, characterized by large air spaces that facilitate buoyancy and gas exchange. These cells are also living and contain protoplasm.

4. **Collenchyma**:
- Collenchyma cells are living cells that provide flexible support to growing parts of the plant. They have unevenly thickened cell walls and contain protoplasm.

Based on the analysis, the correct answer is **Sclerenchyma**, as it is the only cell type listed that is usually dead and lacks protoplasm.

### Step-by-Step Solution:
1. Identify the cell types listed in the question: Parenchyma, Sclerenchyma, Arenchyma, and Collenchyma.
2. Analyze the characteristics of each cell type:
- Parenchyma: Living cells, involved in storage and photosynthesis.
- Sclerenchyma: Dead cells with thick, lignified walls, providing support.
- Arenchyma: Living cells with air spaces, found in aquatic plants.
- Collenchyma: Living cells, providing flexible support to growing parts.
3. Determine which cell type is dead and lacks protoplasm.
4. Conclude that Sclerenchyma is the correct answer.