Phototropism is shoots is attributed to or photoropic movements are due to

Options

A. Auxin
B. Gibberellins
C. Cytokinin
D. Abscisic acid.

Answer

**Step-by-Step Solution:**

1. **Understanding Phototropism**: Phototropism refers to the growth movement of a plant in response to light. In this case, we are specifically discussing the shoots of the plant.

2. **Identifying the Stimulus**: The stimulus for phototropism is light. Plants can detect the direction of light, which influences their growth direction.

3. **Role of Phytohormones**: There are several plant hormones (phytohormones) that regulate growth and movement in plants. The options provided are auxin, gibberellin, cytokinin, and abscisic acid.

4. **Function of Auxin**: Auxin is a specific type of phytohormone that is known to promote cell elongation. When light is coming from one direction, auxin accumulates on the side of the plant that is away from the light (the darker side).

5. **Mechanism of Action**: The accumulation of auxin on the darker side causes those cells to elongate more than the cells on the light-exposed side. This differential growth results in the bending of the plant towards the light source.

6. **Evaluating Other Options**:
- **Gibberellin**: Primarily involved in internode elongation and does not play a direct role in phototropism.
- **Cytokinin**: Mainly responsible for promoting cell division, not specifically involved in phototropic responses.
- **Abscisic Acid**: Functions as a growth inhibitor and does not facilitate phototropism.

7. **Conclusion**: Based on the functions of the hormones discussed, the correct answer to the question is **auxin**.

**Final Answer**: Phototropism in shoots is attributed to auxin.

---