A decapitated plant does not bend towards light because

Options

A. The root sends a message to shoot apex to do so
B. There is accumulation of growth hormones at the cut end
C. The hormone responsible for bending is not available
D. Growth inhibitors are formed.

Answer

To answer the question "A decapitated plant does not bend towards light because," we need to analyze the options provided and understand the role of hormones in plant growth and movement.

### Step-by-Step Solution:

1. **Understanding Phototropism**:
- Phototropism is the growth movement of a plant towards a light source. This is primarily controlled by a plant hormone called auxin, which is concentrated on the side of the plant that is away from the light, causing the cells on that side to elongate and the plant to bend towards the light.

**Hint**: Remember that phototropism is the plant's response to light, and auxin plays a crucial role in this process.

2. **Role of Auxin**:
- Auxin is produced at the tip of the plant (the shoot apex). When light is detected, auxin redistributes itself, accumulating on the shaded side of the plant, promoting growth on that side and causing the plant to bend towards the light.

**Hint**: Think about where auxin is produced and how it affects plant growth direction.

3. **Impact of Decapitation**:
- When a plant is decapitated (the tip is cut off), the source of auxin is removed. Without auxin, the plant cannot respond to light by bending towards it because the necessary hormone for this movement is no longer available.

**Hint**: Consider what happens to hormone levels when the tip of the plant is removed.

4. **Evaluating the Options**:
- Now, let’s evaluate the options given:
- **Root sends a message to shoot apex to do so**: This is incorrect because the root does not send messages to the shoot apex for phototropic responses.
- **There is accumulation of growth hormones at the cut end**: This is misleading; the cut end does not accumulate auxin to promote bending.
- **The hormone responsible for bending is not available**: This is correct because the auxin is absent in a decapitated plant.
- **The growth inhibitors are formed**: This is not relevant to the bending towards light.

**Hint**: Focus on the role of auxin and what happens when it is absent.

5. **Conclusion**:
- The correct answer is: "The hormone responsible for bending is not available." This is why a decapitated plant does not bend towards light.

### Final Answer:
The correct answer is: **The hormone responsible for bending is not available.**