Which of the following statements is not true for metabolically active cells ?

Options

A. They are usually smaller in size
B. Have higher nucleocytoplasmic ratio
C. Have lower surface - volume ratio
D. Have ability to exchange oxygen and waste materials with environment

Answer

To determine which statement is not true for metabolically active cells, let's analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding Metabolically Active Cells**:
- Metabolically active cells are those that are engaged in various biochemical processes, including energy production, synthesis of molecules, and waste removal.

2. **Analyzing Statement 1**:
- **Statement**: "They are usually smaller in size."
- **Analysis**: This statement is true. Metabolically active cells tend to be smaller because a smaller size allows for more efficient nutrient uptake and waste removal.

3. **Analyzing Statement 2**:
- **Statement**: "They have a higher nucleocytoplasmic ratio."
- **Analysis**: This statement is also true. A higher nucleocytoplasmic ratio means that there is more nucleus relative to the cytoplasm, which is typical in cells that are actively synthesizing proteins and other molecules.

4. **Analyzing Statement 3**:
- **Statement**: "They have a lower surface volume ratio."
- **Analysis**: This statement is false. Metabolically active cells generally have a higher surface area to volume ratio, which facilitates better exchange of materials (nutrients and waste) with the environment. A lower surface volume ratio would hinder this exchange.

5. **Analyzing Statement 4**:
- **Statement**: "They have the ability to exchange oxygen and waste materials with the environment."
- **Analysis**: This statement is true. Metabolically active cells must exchange gases and waste materials with their environment to maintain metabolic processes.

### Conclusion:
The statement that is **not true** for metabolically active cells is **Statement 3**: "They have a lower surface volume ratio."