An electron carrier before it harvests energy from glucose molecules in a series of gradual steps is:
a) Pyruvate.
b) AMP.
c) ATP.
d) NAD⁺.
e) NADH.

Redox reactions ______.

a. transfer energy

b. transfer electrons

c. involve oxidation and reduction

d. are involved in all of the above

A reduced molecule ______.

a. has gained electrons

b. has become more positive in charge

c. has lost electrons

d. is an electron donor

Oxidation is the _________________________, and reduction is the _________________________.

a) Gain of electrons; Loss of electrons.

b) Gain of protons; Loss of protons. 

c)  Loss of electrons; Gain of electrons.

d)  Gain of oxygen; Loss of oxygen.

When glucose donates electrons to NAD⁺ creating NADH, the glucose molecule becomes:

a) Hydrolyzed.

b) Oxidized.

c) Neutral.

d) Reduced.

NADH is commonly used as an electron carrier during the breaking down of complex molecules like glucose in cellular respiration. NADPH is also a common electron carrier. However, NADPH is used to build complex molecules like glucose in a process called:

Which electron carrier is not matched with its correct function.

Define oxidation-reduction, and differentiate the following terms:

a. aerobic and anaerobic respiration

b. respiration and fermentation

c. cyclic and noncyclic photophosphorylation

Why must NADH be reoxidized? How does this happen in an organism that uses respiration? Fermentation?