Development of shoot and root is determined by

Options

A. Cytokinin and auxin ratio
B. Enzymes
C. Temperature
D. Plant nutrients.

Answer

### Step-by-Step Solution

1. **Understanding the Question**: The question asks what determines the development of the shoot and root in plants.

2. **Identifying Key Factors**: The options provided are:
- Cytokinin and auxin ratio
- Enzymes
- Temperature
- Plant nutrients

3. **Analyzing the Role of Auxins and Cytokinins**:
- Auxins (like IAA, NAA, IBA) are hormones that promote root development.
- Cytokinins (like BAP) promote shoot development.

4. **Understanding the Ratio**:
- A **high ratio of auxins to cytokinins** leads to root initiation.
- A **low ratio of auxins to cytokinins** leads to shoot development.

5. **Evaluating Other Options**:
- **Enzymes**: While they play a role in various plant processes, they do not specifically determine shoot and root development.
- **Temperature**: It affects metabolic processes but does not directly determine the development of shoots and roots.
- **Plant Nutrients**: They are essential for overall plant health but do not specifically dictate the development of shoots and roots.

6. **Conclusion**: The development of the shoot and root is primarily determined by the **cytokinin and auxin ratio**. Therefore, the correct answer is option 1.

### Final Answer
The development of shoot and root is determined by the **cytokinin and auxin ratio**.

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