Question

The ultimate electron acceptor of respiration in aerobic organism is:
A. Cytochrome
B. Oxygen
C. Hydrogen
D. Glucose

Answer 1

Hint: Respiration is defined as the physical or chemical process by which the organism supplies the oxygen to the cells or the tissues which are required for the metabolism. Cellular respiration is the set of metabolic reactions to convert chemical energy from oxygen molecules. Respiration is a catabolic process which breaks the larger molecules to small molecules and produces energy.

Complete answer:
Respiration is defined as the physical or chemical process by which the organism supplies the oxygen to the cells or the tissues which are required for the metabolism. Catabolic process in which larger molecules are broken into smaller molecules by the break of high energy bonds to yield energy.
Option A is incorrect because cytochrome has redox active proteins with haem, Fe atom and a cofactor. They are classified on the basis of type of haem and its binding. They are involved in redox catalysis and in electron transport chains. Examples of cytochrome are cytochrome a, cytochrome b, cytochrome c and cytochrome d.
Option B is correct because the electron transport chain catalyses the electron flow from NADH to oxygen which is the final acceptor of respiration in aerobic organisms. Molecular oxygen acts as a high oxidizing agent and therefore its an excellent acceptor of electrons.
Option C is incorrect because, hydrogen is a source of clean energy and has application in food industries, petrochemical refinery and in metallurgy. It is a gas with very less viscosity and is used to test the leakage of gas in a device.
Option D is incorrect because glucose is a form of sugar with a chemical formula of $C_6H_{12}O_6$. It is a subcategory of carbohydrates and it is the most abundant monosaccharide. It is mainly produced during the process of photosynthesis in plants and in some algae, with the use of sunlight, carbon dioxide and water.

Therefore, option B is the correct answer.

Note:
Respiration is defined as the physical or chemical process by which the organism supplies the oxygen to the cells or the tissues which are required for the metabolism.the electron transport chain catalyses the electron flow from NADH to oxygen which is the final acceptor of respiration in aerobic organisms.