Q1. Green plants in the sea are useful for the respiration of fish because
(a) They give out oxygen
(b) They give out carbon dioxide
(c) The give out oxygen and carbon dioxide simultaneously
(d) They take oxygen and give out carbon dioxide
(UPSC Prelims, 1979)
Answer: (a) They give out oxygen
Explanation: Aquatic plants and algae perform photosynthesis, releasing oxygen into the water, which is essential for fish respiration. This process helps maintain oxygen levels in aquatic ecosystems, supporting marine life.
