Question

During deficiency of oxygen in tissues of human beings, pyruvic acid is converted into lactic acid in the:
a) Cytoplasm
b) Chloroplast
c) Mitochondria
d) Golgi body

Answer 1

Hint:- Pyruvic acid is converted into lactic acid, under the anaerobic activity occurring in the cells. This anaerobic condition is made when there is strenuous activity done by the body. The body in such conditions is unable to take in ample amounts of oxygen.

Complete Answer:-
Pyruvate is formed by glycolysis, enters into Krebs cycle and forms energy molecules. It is the source of ATP molecules. Pyruvate, in the absence of oxygen, alternates its path and forms a lactic acid molecule. This helps in the occurrence of anaerobic cellular respiration. This type of respiration occurs in the cytoplasm. When strenuous activity is done, the body is in demand for oxygen which is needed for aerobic respiration in the tissues of the body to produce ATP. This is compromised as enough oxygen is not available. This leads to anaerobic respiration in the body in which the end product formed is lactic acid. As the intensity of the exercise is very high, the amount of lactic acid formed in the muscles is also high. In blood, lactate breaks down into lactate and hydrogen ions. Lactate gets used up by the mitochondria of the cells and the hydrogens ions present get accumulated in the muscle. This causes difficulty in the contraction of the muscles hence causing immense pain to the person. Though this muscle pain is not permanent, it causes extreme discomfort to the person.

Thus, the right option is A.

Note:- The formation of lactic acid in the muscles leads to the formation of lactate in the blood. The formation of lactic acid during exercise is difficult to control. But there is a huge accumulation of lactic acid whenever we run very fast.