Question

1. NADH and FADH2 deliver their high energy electrons to

A. glycolysis

b. the electron transport chain

c. oxygen

2. In fermentation, which set of pathways is running, or operating?

A. glycolysis

b. transition

c. Kreb's cycle (also called TCA cycle or citric acid cycle)

d. electron transport chain

e. all of the above

3. As electrons are passed down the electron transport chain, the energy is used to pump ______ across the membrane.

A. B.H+, or hydrogen ions

b. NADH

c. H20

Answer 1

1. Electron transport chain

NADH and FADH2 synthesized during glycolysis, pyruvate oxidation and citric acid cycle are high energy electron Carriers. They donate their electrons to electron transport chain taking place in inner mitochondrial membrane. The electrons are passed from one electron carrier to the other, all of which are arranged according to their increasing order of electrode potential. Ultimately the electrons are accepted by oxygen to form water.

2. Glycolysis

​​​​​​Fermentation is the process of breakdown of sugar in the deficiency of oxygen. It is divided into two steps, glycolysis and fermentation. In glycolysis, sugar is partially oxidized into pyruvic acid and in fermentation, pyruvic acid is is converted into lactic acid or ethanol along with the formation of carbon dioxide. It is energetically very less efficient process because it leads to the formation of only four molecules of ATP which occur in glycolysis.

3. Hydrogen ions

During electron transport chain, electrons are transferred from one electron carrier to the other. In this process, protons are also pumped from mitochondrial Matrix to intermembrane space. These protons are pumped back into the mitochondrial matrix by ATP synthase enzyme. The electrochemical energy stored in this gradient is used by this enzyme to synthesise ATP.

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