Minerals cannot be only passively absorbed by root because:
(a) Membrane in permeable to ions
(b) Cocentration of minerals in soil is lower
(c ) Minerals are present in soil as charged particles

Options

A. a,b,c correct
B. a and b correct
C. b and c correct
D. a and c correct

Answer

To solve the question, "Minerals cannot be only passively absorbed by roots because:", we need to analyze the given options and understand the concepts of mineral absorption in plants.

### Step-by-Step Solution:

1. **Understanding Passive Absorption**:
- Passive absorption refers to the movement of substances across cell membranes without the expenditure of energy, typically following the concentration gradient (from high concentration to low concentration).

2. **Analyzing Option (a)**:
- **Statement**: "Membrane is permeable to ions."
- **Explanation**: If the membrane were permeable to ions, then passive absorption could occur. Therefore, this statement does not explain why minerals cannot be absorbed passively.
- **Conclusion**: This option is incorrect.

3. **Analyzing Option (b)**:
- **Statement**: "Concentration of minerals in soil is lower."
- **Explanation**: If the concentration of minerals in the soil is lower than that inside the root cells, then passive absorption cannot occur because it would require movement against the concentration gradient. This scenario necessitates active transport, which requires energy.
- **Conclusion**: This option is correct.

4. **Analyzing Option (c)**:
- **Statement**: "Minerals are present in soil as charged particles."
- **Explanation**: Minerals in the soil exist as charged ions (cations and anions). Charged particles cannot easily cross the lipid bilayer of cell membranes without assistance. Therefore, their absorption requires specific transport mechanisms, often active transport.
- **Conclusion**: This option is also correct.

5. **Final Conclusion**:
- Since options (b) and (c) correctly explain why minerals cannot be only passively absorbed by roots, the answer to the question is that minerals cannot be absorbed passively due to the low concentration in the soil and their presence as charged particles.

### Final Answer:
The correct options are (b) and (c).