Chapter 8, Problem 35A

Summary Introduction

Introduction :

A process by which organisms obtain energy is called cellular respiration. The function of cellular respiration is to harvest electrons from carbon compounds such as glucose to produce energy. Cellular respiration occurs two phases namely glycolysis and aerobic respiration. The glycolysis, is an anaerobic process and does not require oxygen. Aerobic respiration includes the Krebs cycle and electron transport that requires oxygen. Lactic acid fermentation is not a stage of cellular respiration.

Answer to Problem 35A

Correct answer :

The correct answer is option (D) Lactic acid fermentation.

Explanation of Solution

Explanation/justification for the correct answer :

Option (D) Lactic acid fermentation. The anaerobic pathway that follows glycolysis is called anaerobic respiration or fermentation. Lactic acid fermentation is one such anaerobic respiration. In lactic acid fermentation, enzymes converts pyruvate into lactic acid with using oxygen. Therefore, it is not a part of cellular respiration. Thus, the correct answer is option (D).

The explanation for the incorrect answer :

Option (A) glycolysis. Glycolysis is the first stage of cellular respiration that occur in the cytoplasm without using oxygen. Thus, this is an incorrect option.

Option (B) Krebs cycle. Krebs cycle or TCA cycle or citric acid cycle occurs in mitochondrial matrix where enzymes for reactions are present. It is a part of cellular respiration. Thus, this is an incorrect option.

Option (C) electron transport. Electron transport chain occurs on the inner membrane of the mitochondria, where termination oxidation take place. It produces large amount of ATPs.  Thus, this is an incorrect answer.