To solve the question regarding the assertion and reason related to the cymose tap root system, we will break down the information step by step.
### Step 1: Understand the Assertion
The assertion states that in a cymose tap root system, the oldest branch lies very close to the growing point of the root, while the youngest branch is farthest away from it.
**Explanation**: In a cymose tap root system, the primary root does not continue to grow indefinitely. Instead, it stops growing after a certain period, and the secondary roots take over the growth. As a result, the oldest branches (which are part of the primary root) are located near the growing point, while the younger branches (which are the secondary roots) extend further away.
### Step 2: Understand the Reason
The reason provided states that in a cymose tap root system, the primary root itself stops growing after some time, but the secondary roots carry on the further growth of the system.
**Explanation**: This is true because in a cymose tap root system, the primary root does not elongate indefinitely. Once it reaches a certain stage, it ceases to grow, and the secondary roots continue to develop and grow, contributing to the overall root system.
### Step 3: Analyze the Relationship
Now, we need to analyze whether the reason correctly explains the assertion.
- The assertion is correct: the oldest branches are indeed closer to the growing point, and the youngest branches are farther away.
- The reason is also correct: the primary root stops growing while secondary roots continue to grow.
Since the reason provides a valid explanation for the assertion, we conclude that both the assertion and reason are correct, and the reason is the correct explanation for the assertion.
### Conclusion
Thus, the correct answer is that both the assertion and reason are true, and the reason is the correct explanation of the assertion.
