Question

The process that takes place within a cellular organelle is

• A. I only
• B. III only
• C. I and II
• D. II and III
• E. I, II, and III

Answer 1

The correct option is D II and III

Glycolysis (I) is the first step of cellular respiration, that breaks down glucose into two molecules of pyruvic acid, independent of presence or absence of oxygen and occurs in the cytoplasm. The pyruvic acid is then decarboxylated into acetyl-CoA and enters Kreb cycle (II), wherein it is aerobically broken down; the pathway takes place in the mitochondrial matrix. Electron transport chain (III) includes downhill flow of electrons from NADH and FADH2 to the final electron acceptor (Oxygen) through a chain of membrane-bound carriers to facilitate the uphill transport of protons across a proton-impermeable membrane. The proton-motive force, that drives protons back into the matrix provides the energy for ATP synthesis. Electron transport system is oxygen-dependent process and occurs in the inner mitochondrial membrane. The correct answer is D.