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 regarding why minerals cannot be only passively absorbed by roots, we can analyze each option provided:

1. **Understanding Passive vs. Active Absorption**:
- Passive absorption occurs when substances move along a concentration gradient without the use of energy. In contrast, active absorption requires energy to move substances against their concentration gradient.

2. **Analyzing the Options**:
- **(a) Membrane is permeable to ions**: This statement suggests that if the membrane were permeable, passive absorption could occur. However, this is not the primary reason why minerals cannot be passively absorbed. Thus, this option is not a valid reason.

- **(b) Concentration of minerals in soil is lower**: This statement indicates that the concentration of minerals in the soil is lower than in the plant roots. Since minerals would need to move against the concentration gradient to enter the roots, this necessitates active transport. Therefore, this option is a valid reason.

- **(c) Minerals are present in soil as charged particles**: Minerals in the soil exist as ions (charged particles). Charged particles cannot easily pass through the lipid bilayer of cell membranes without assistance. This means that active transport mechanisms are required to move these ions into the plant roots. Thus, this option is also a valid reason.

3. **Conclusion**:
- Based on the analysis, the correct reasons why minerals cannot be only passively absorbed by roots are:
- (b) The concentration of minerals in the soil is lower than in the roots, requiring active transport.
- (c) Minerals are present in soil as charged particles, which cannot passively diffuse through the cell membrane.

Therefore, the correct answer to the question is **(b) and (c)**.