Question

Which of the following is most appropriate for aerobic respiration?
A) \[{\text{Glucose}}\xrightarrow{{Mitochondria}}Pyruvate\xrightarrow{{Cytoplasm}}C{O_2} + {H_2}O + energy\]
B) \[{\text{Glucose}}\xrightarrow{{Cytoplasm}}Pyruvate\xrightarrow{{Mitochondria}}C{O_2} + {H_2}O + energy\]
C) \[{\text{Glucose}}\xrightarrow{{Cytoplasm}}Pyruvate + energy\xrightarrow{{Mitochondria}}C{O_2} + {H_2}O\]
D) \[{\text{Glucose}}\xrightarrow{{Cytoplasm}}Pyruvate + energy\xrightarrow{{Mitochondria}}CO + {H_2}O + energy\]

Answer 1

Hint: Aerobic respiration is the breakdown of glucose in the presence of oxygen. The by-product of respiration is carbon dioxide and water. The energy is also produced in the mitochondria of the cells in the form of ATP.

Complete answer:
By aerobic respiration, we mean the breakdown of food by oxygen to liberate energy in the form of ATP. Glucose is a simple carbohydrate that is metabolised to liberate ATP which is the usable form of energy. As glucose is a 6C carbohydrate, it on oxidation liberates carbon dioxide and water along with energy.

Let us discuss the steps of aerobic respiration:
i) Glycolysis- It takes place in the cytoplasm and forms pyruvate.
ii) Kreb cycle- It occurs in the mitochondria in which the pyruvate is converted to Acetyl CoA and liberates energy in the form of NADH which cannot be utilised by the cell.
iii) Electron transport chain- The end products of ETC are carbon dioxide, water and ATP.

Pyruvic acid is the key product of glycolysis. The fate of pyruvic acid depends upon cellular needs. There are three major ways in which different cells handle pyruvic acid. These are lactic acid fermentation, alcoholic and Aerobic fermentation.

In aerobic respiration, Glucose is broken down into two molecules of 3C Pyruvate in the cytoplasm. The pyruvate is then oxidized in presence of $O_2$ to release Energy. $Co_2$ and $H_2O$ are formed as by-products.

Therefore the correct answer is option ‘C’.

Note: The glucose is broken down to pyruvate in the cytoplasm and the pyruvate is transported to the mitochondria for the synthesis of energy in the form of ATP and release of by-products carbon dioxide and water. By this process, the chemical energy present in the glucose is converted into ATP or Adenosine triphosphate.