Question

Which metabolic pathway is common to both fermentation, a type of aerobic respiration, and aerobic respiration?
A) Glycolysis
B) Krebs Cycle
C) Electron transport chain
D) Acetyl Co-A formed from Pyruvate
E) Chemiosmosis

Answer 1

Hint: Organisms such as prokaryotes and eukaryotes use metabolic pathways such as glycolysis and Kreb’s cycle to breakdown food to produce energy. The cellular respiration occurs in the presence as well as in the absence of oxygen.

Complete solution:
A. Glycolysis: Glycolysis is a part of cellular respiration and is common to both aerobic and anaerobic respiration. It occurs in the cytosol of the cells. It is an enzyme controlled 10 steps reaction by which glucose, fructose or sucrose is reduced from 6 carbon compounds to pyruvate with the production of ATP and NADH.
B. Krebs Cycle: It is a cycle that occurs after glycolysis, and this cycle generates more energy as compared to other cycles of the cellular respiration. It takes place in the mitochondria.
C. Electron transport chain: The electron transport chain is a series of a complex chain of proteins that transfer electrons from electron donors to electron acceptors via a redox reaction. The electron transport chain occurs in the inner membrane of the mitochondria in eukaryotic cells and in the cellular membrane of prokaryotes.
D. Acetyl Co-A formed from Pyruvate: Acetyl Co-A is generated either by oxidative decarboxylation of pyruvate from glycolysis. It occurs in the mitochondrial matrix.
E. Chemiosmosis: Chemiosis describes the movement of ions down the electrochemical gradient across a membrane that results in the ATP formation.
Thus, the answer is option A.

Note: Aerobic respiration uses oxygen to breakdown glucose, fatty acids and amino acids to produce ATP. Pyruvate is converted into two acetyl Co-A which is used in the Krebs cycle inside the mitochondrial matrix. The Krebs cycle takes place two times for each molecule of glucose. The inner mitochondrial matrix has an arrangement of proteins complex which ensures that the electron passes from one reacting molecule to the other. A total of 38 molecules of ATP is produced in one cellular reaction.