Question

Which of the following plays a major role in replacing oxygen in the atmosphere?
A. Green plants
B. The weathering rocks
C. Fossil- fuel combustion
D. All of the above

Answer 1

Hint:- The most important role in producing the oxygen present in earth’s atmosphere is the process called ‘Photosynthesis’, it is carried out by green plants which are key of keeping our environment fresh and healthy except plants no solid source is present on earth which can produce oxygen.

Complete answer: Plant synthesizes their food with the help of a process called photosynthesis, in which the plant uses light and then the water molecules split and releases the oxygen in the surroundings. Oxygen is needed for breathing for almost all living creatures on earth so plants respire but they need carbon dioxide instead of oxygen. The plants combine water, carbon dioxide and sun’s energy to produce sugar and oxygen, the cells present in green parts of the plants where photosynthesis takes place use oxygen wherever they need for its growth and development. The sugar which is produced further produces carbon dioxide as a by-product. Photosynthesis can only take place in the plant which is green in colour and which has chlorophyll pigment in them. During the respiration plants consume food to keep plant cells alive whereas during photosynthesis plants create their own food. Hence we can easily conclude that the correct answer is option (A) Green plants.

Note:- We need to keep in mind this fact that plants respire all the time in day as well as at night, but photosynthesis only takes place during daytime as it needs light for preparing its food which is not available at night. During bright light photosynthesis rate is higher while it becomes equal to respiration rate in dim light.