Question

(i) Some forms of life do not depend upon oxygen. Explain.
(ii) Explain the various forms in which carbon is found on the Earth.
(iii)What is respiration?

Answer 1

(i) It is interesting to note that some forms of life, especially, bacteria are poisoned by element oxygen. Also the process of fixation of nitrogen by bacteria does not take place in the presence of oxygen.

(ii) Carbon in elemental form occurs as diamond and graphite. Carbon in combined state occurs as carbon dioxide, carbonates and hydrogen carbonate salts in various minerals. It occurs in carbon containing molecules like carbohydrates, fats, proteins, nucleic acids and vitamins etc.

(iii) Respiration is a process in which oxygen may or may not be used to convert glucose back into carbon dioxide.