Assertion : Aerobic respiration involves the exchange of respiratory gases twice.
Reason : Exchange occurs from lung to heart and then heart to lung.

Explanation

To analyze the given assertion and reason, we will break down the statements step by step.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Aerobic respiration involves the exchange of respiratory gases twice."
- In aerobic respiration, oxygen is taken in and carbon dioxide is released. This process indeed involves two main sites of gas exchange: the lungs and the tissues.

2. **Gas Exchange in the Lungs**:
- The first exchange occurs in the lungs (specifically in the alveoli). Here, oxygen (O2) from the air in the alveoli diffuses into the blood in the capillaries, while carbon dioxide (CO2) from the blood diffuses into the alveoli to be exhaled.

3. **Gas Exchange in the Tissues**:
- The second exchange occurs at the tissue level. Oxygen carried by the blood is delivered to the tissues, where it is utilized for cellular respiration. Simultaneously, carbon dioxide produced by the tissues as a waste product diffuses back into the blood.

4. **Conclusion on the Assertion**:
- Since the assertion correctly describes the process of aerobic respiration involving two exchanges of gases (one in the lungs and one in the tissues), we conclude that the assertion is **true**.

5. **Understanding the Reason**:
- The reason states that "Exchange occurs from lung to heart and then heart to lung."
- However, this statement is misleading. The heart does not participate in the exchange of gases. Its role is to pump blood throughout the body, not to facilitate gas exchange.

6. **Conclusion on the Reason**:
- Since the reason incorrectly describes the process of gas exchange, we conclude that the reason is **false**.

7. **Final Evaluation**:
- The assertion is true, and the reason is false. Therefore, the correct answer is that the assertion is correct, and the reason is incorrect.

### Final Answer:
- The assertion is true, and the reason is false.