Geotropic response of root is due to

Options

A. Higher auxin content of stem
B. Higher growth on upper side of root
C. Lower rate of growth in the stem
D. Higher rate of growth in the stem.

Answer

### Step-by-Step Solution:

1. **Understanding Geotropism**:
- Geotropism refers to the growth response of a plant to gravity. It can be classified into two types: positive geotropism (growth towards gravity) and negative geotropism (growth away from gravity).

2. **Role of Auxin**:
- Auxin is a plant hormone that plays a crucial role in regulating plant growth. It influences cell elongation and is unevenly distributed in plant tissues, particularly in response to gravity.

3. **Geotropic Response in Roots**:
- Roots exhibit positive geotropism, meaning they grow towards the gravitational pull. This is due to the higher concentration of auxin on the lower side of the root.

4. **Auxin Distribution**:
- In the case of roots, when the plant is oriented vertically, auxin accumulates on the lower side due to gravity. This higher concentration of auxin on the lower side stimulates more growth in that region, causing the root to bend downwards.

5. **Growth Patterns**:
- The upper side of the root has a lower concentration of auxin, leading to less growth in that area. Thus, the root grows faster on the lower side where auxin concentration is higher, resulting in a downward growth direction.

6. **Conclusion**:
- The geotropic response of roots is primarily due to the differential distribution of auxin, which causes greater growth on the side with higher auxin concentration (the lower side of the root).

### Final Answer:
The geotropic response of roots is due to the higher auxin concentration on the lower side of the root, which promotes greater growth in that area.

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