The correct option is (c).
Explanation
Respiration is a biochemical process occurring within the cells of living organisms. It involves the catabolic breakdown of respiratory substrates (primarily glucose) to release energy, which is subsequently stored in the form of Adenosine Triphosphate (ATP).
Statement-wise Analysis
- Statement 1 is Incorrect. Aerobic respiration takes place in the presence of oxygen and leads to the complete oxidation of glucose into carbon dioxide and water. This process releases a significant amount of energy (approximately 36 to 38 ATP molecules per glucose molecule). It is an energy-yielding process, not one that consumes energy without release.
- Statement 2 is Correct. Anaerobic respiration occurs in the absence of oxygen. Although it results in the partial breakdown of glucose and yields significantly less energy compared to aerobic respiration (net gain of 2 ATP molecules), it is still an energy-releasing process.
- Statement 3 is Correct. The fundamental definition of cellular respiration is the enzymatic breakdown of food nutrients (such as carbohydrates, fats, and proteins) within the cell to release chemical energy stored in their bonds.
Key Takeaway
Cellular Respiration is universally an exergonic (energy-releasing) process. Both aerobic and anaerobic respiration involve the breakdown of food substrates to generate ATP, differing only in the presence of oxygen and the magnitude of energy released.