AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
The amount of oxygen dissolved in water is much lower than in air, so aquatic organisms must breathe faster to get sufficient oxygen for their body processes.
The examiner expects one specific biological reason: low dissolved oxygen content in water forces aquatic organisms to process more water rapidly. This is directly linked to the concept of respiration and oxygen availability covered in Chapter 6 (Life Processes). Keep the answer to one crisp line for 1 mark.