Question 24
Oxygen is returned to the atmosphere mainly by:
(a) burning of fossil fuel
(b) respiration
(c) photosynthesis
(d) fungi
(c) photosynthesis
Burning fossil fuels results in the emission of carbon dioxide in the atmosphere. Respiration is involved in water cycle whereas photosynthesis is the process by which plants make their food in the presence of carbon dioxide and sunlight, and gives out oxygen to the atmosphere.