Question

What is true for respiration?
A) Oxygen is essential
B) Oxygen combines with carbon to form $CO_2$
C) Oxygen combines with hydrogen to produce water
D) Oxygen is not essential

Answer 1

Hint: Respiration is a physiological process which occurs in all living organisms. The food is broken down by the respiration. This releases energy. It involves exchange of gaseous from the environment to the cells.

Complete answer:
To answer this question, we must know about the process of respiration. The respiration is a physical and chemical process by which the organisms take in oxygen which is taken up for the oxidation of the food (carbohydrate) and release energy in the form of ATP. Carbon dioxide and water are released as a by-product. The oxygen is taken in from the environment to the cells and tissues whereas the carbon dioxide is transported in the opposite direction that is from the tissues to the environment.

The equation of respiration is represented as:
Glucose + Oxygen 🡪 carbon dioxide + water.

The respiration occurs both aerobically (in the presence of oxygen) and anaerobically when oxygen is not required as in case of certain bacteria, in the muscles during strenuous exercise. In the Electron transport chain, the hydrogen combines with the oxygen to produce water.

Thus the correct answer is option (C).

Note: Anaerobic respiration produces ethyl alcohol or lactic acid along with the ATP. It is generally seen in the lower animals. It produces energy quickly as compared to aerobic respiration. In human beings, the lactic acid gets accumulated in the muscles. This causes muscle fatigue.