Auxin and cytokinin are antagonistic in which of the following funtions ?

Options

A. Cell division
B. Phototropism
C. Apical dominance
D. Geotropism

Answer

To answer the question regarding the antagonistic functions of auxin and cytokinin, we can break down the information step by step:

### Step-by-Step Solution:

1. **Understanding Auxin and Cytokinin**:
- Auxin is a plant hormone that primarily promotes cell elongation and is involved in various growth processes, including apical dominance.
- Cytokinin is another plant hormone that promotes cell division and is involved in the growth of lateral buds.

2. **Defining Apical and Lateral Dominance**:
- Apical dominance refers to the phenomenon where the main central stem of the plant grows more vigorously than the side branches (lateral buds). This is primarily regulated by auxin.
- Lateral dominance, on the other hand, is the growth of lateral buds which is promoted by cytokinin.

3. **Role of Auxin in Apical Dominance**:
- Auxin promotes the growth of the apical bud, leading to the suppression of lateral buds. This means that when auxin levels are high, the plant will focus its energy on growing taller rather than producing side branches.

4. **Role of Cytokinin in Lateral Bud Growth**:
- Cytokinin encourages the growth of lateral buds, which can lead to the development of more branches and a bushier appearance of the plant. When cytokinin is present in higher amounts, it can counteract the effects of auxin.

5. **Conclusion on Antagonistic Functions**:
- Therefore, auxin and cytokinin have antagonistic functions in regulating apical and lateral dominance. Auxin promotes apical dominance while inhibiting lateral bud growth, whereas cytokinin promotes lateral bud growth and inhibits apical dominance.

### Final Answer:
Auxin and cytokinin are antagonistic in the function of regulating apical and lateral dominance in plants.

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