The correct option is (c) 2 and 3 only
Explanation
Cellular respiration is a fundamental metabolic process in all living organisms, including plants. It involves the oxidation of organic compounds (like glucose) to release energy in the form of ATP, essential for survival. This process is distinct from and often opposite to photosynthesis in terms of gas exchange.
Statement-wise Analysis
- Statement 1 is Incorrect. Plants, like animals, are living organisms that require energy for various physiological activities. To generate this energy, plants do consume oxygen to break down glucose during cellular respiration. While plants release oxygen as a byproduct of photosynthesis, they simultaneously consume oxygen for respiration.
- Statement 2 is Correct. The chemical process of aerobic respiration involves using oxygen to break down glucose, resulting in the production of energy, water, and carbon dioxide ($CO_2$). This $CO_2$ is released into the environment (or used in photosynthesis during the day).
- Statement 3 is Correct. Respiration is a vital life process that must occur continuously to sustain the plant. Therefore, respiration takes place throughout the day and night. In contrast, photosynthesis is light-dependent and typically occurs only during the day. During the day, the rate of photosynthesis usually exceeds respiration, leading to a net release of oxygen; at night, only respiration occurs, leading to a net release of carbon dioxide.
Key Takeaway
Respiration is a continuous process (24/7) in plants where $O_2$ is consumed and $CO_2$ is released.
Photosynthesis is a daytime process where $CO_2$ is consumed and $O_2$ is released.