Assertion : A correct concentration of auxin and cytokinin is required for the development of root and shoot in callus.
Reason: When the ratio of kinetin to auxin is high only shoot develop but when the ratio is low only roots develop

Options

A. if both are true with reason being correct explanation
B. both true but reason in not correct explantion
C. assertion true but reason is wrong
D. both are wrong

Answer

To solve the assertion-reason question, let's break it down step-by-step:

### Step 1: Understand the Assertion
The assertion states that "A correct concentration of auxin and cytokinin is required for the development of root and shoot in callus."
- **Explanation**: Auxins and cytokinins are plant hormones that play crucial roles in plant growth and development. The correct balance of these hormones is essential for the differentiation of tissues, including roots and shoots from callus tissue.

**Hint**: Recall the roles of auxins and cytokinins in plant tissue culture.

### Step 2: Understand the Reason
The reason states that "When the ratio of kinetin to auxin is high, only shoots develop, but when the ratio is low, only roots develop."
- **Explanation**: Kinetin is a type of cytokinin. A high ratio of kinetin (cytokinin) to auxin promotes shoot formation, while a low ratio favors root formation. This is a well-established principle in plant tissue culture.

**Hint**: Think about how different hormone ratios influence plant tissue differentiation.

### Step 3: Evaluate the Truth of Assertion and Reason
- Both the assertion and the reason are true statements based on plant physiology and tissue culture practices.
- The reason correctly explains the assertion by detailing how the ratios of auxin and cytokinin affect the development of roots and shoots.

**Hint**: Consider how the reason supports the assertion logically.

### Step 4: Choose the Correct Option
Based on the evaluation:
- Option 1 states that both are true, with the reason being a correct explanation of the assertion. This is the correct choice.
- The other options are incorrect because they either claim one of the statements is false or that the reason does not explain the assertion.

**Final Answer**: Option 1 is correct: Both the assertion and reason are true, and the reason is the correct explanation for the assertion.

### Summary of Steps:
1. Analyze the assertion about the role of auxin and cytokinin.
2. Analyze the reason regarding the ratios of kinetin and auxin.
3. Determine the truth of both statements.
4. Select the correct option based on the evaluation.