Question

In muscles, anaerobic conditions change pyruvic acid to
A. $C_{2}H_{5}OH$
B. $C_{3}H_{4}O_{3}$
C. $C_{3}H_{6}O_{3}$
D. $C_{2}H_{4}O$

Answer 1

Hint: Muscles respire anaerobically only for a short time. During anaerobic condition, muscles do not use oxygen to make energy from sugar. It usually takes place during strenuous exercise.

Complete Answer:
- This type of anaerobic condition in muscles occurs due to strenuous exercise. The pyruvate obtained from glycolysis is converted to lactate and is stored in the muscles and liberate certain amount of energy in the form of ATP. This process unlike aerobic respiration does not use oxygen.
- The anaerobic condition is shorter but harder to the muscles.
The process involves chemical reaction in which energy from glucose is transferred to the cell. Anaerobic respiration produces lactic acid. Carbon dioxide and water are not formed. It involves enzymatic fermentation. This leads to painful muscle cramps.
   $C_{6}H_{12}O_{6} \to C_{3}H_{6}O_{3} (lactic acid) + 2ATP$

The energy liberated from this reaction is very less than that of aerobic respiration.
Anaerobic respiration takes place in the cell at some point of time.
Alcoholic fermentation in the cells liberates ethanol i.e. $C_{2}H_{5}OH$.
$C_{3}H_{4}O_{3}$ and $C_{2}H_{4}O$ are not any of the respiratory products.

The correct answer is (C). The anaerobic respiration in muscles produce lactate.

Additional Information: Yeast and other microorganisms ferment glucose to ethanol. This process is called alcoholic fermentation. It is used in synthesis of beer, and other products like ethanol.

Note: This is a temporary process. When the lactic acid is built up in muscles, the muscles feel sore and painful. This respiration helps the athletes build up muscle power.