MCB 181R, Fall 2007
Instructor: Dr. S. Jorstad
For multiple choice questions
(each worth 3 points), bubble
correct answers (there
may be more than one); there is a 1 point penalty for incorrect answer choices.
(each worth 5 points): confine your answers to the space provided on the
scansheet. Writing outside those margins will adversely affect the machine-scoring of
your exam. You may use bulleted points to express yourself, as long as your meaning is
1. The energy in a molecule, such as glucose,
a. exists in its covalent bonds. *
b. can be captured when the bonds are broken (e.g., by an enzyme) and the
energy is transferred to another molecule. *
= a description of glycolysis
c. must be released in a slow, step-wise fashion, or much of it will be lost to
entropy (e.g., heat and light). *
ditto; contrast between respiration and a
forest fire (both examples of oxidation of glucose)
d. is released in an overall endergonic reaction.
exergonic (gives off energy)
e. is in its protons, which can be passed from one molecule to the next.
true of electrons, but not protons
a. is a reducing agent.
oxidizing agent (pulls electrons off of other molecules)
b. can grab electrons from other molecules, and thereby help in extracting the
energy in those molecules. *
c. is reduced to NADH during glycolysis, pyruvate oxidation, and the citric
acid cycle. *
(see Fig 7.9 or 7.16 in 7
edition; 7.7 in 8
d. can be regenerated by the ETC, as it oxidizes NADH. *
(Figs. 7.10, 7.12 in
; 7.11, 7.13 8
e. cannot be regenerated in organisms that live by fermention; they must
continuously synthesis new NAD
fermentation’s whole purpose is
to regenerate NAD+
Short Essay #1: Two of the products of glycolysis are pyruvate and NADH. What
happens to each of these molecules in 1) cellular respiration and 2) fermentation?
cellular respiration, pyruvate is completely OXIDIZED (by pyruvate oxidation and the
CAC), and NADH is oxidized by the ETC. 2) In fermentation, pyruvate is REDUCED, as
NADH hands back its electrons and is thereby oxidized back to NAD+ (NADH is
oxidized by pyruvate).
3. The goal of breaking down glucose molecules is to use the energy in the glucose to
make ATP—the main form of energy cells use to run endergonic reactions. During
this process, for every molecule of glucose,