5 Steps to a 5 AP Biology, 2014-2015 Edition
Respiration ❮ 71
❯ Answers and Explanations
- C—This is the concept of chemiosmosis: the
coupling of the movement of electrons down the
electron transport chain and the formation of
ATP via the creation of a proton gradient. The
protons are pushed out of the matrix during the
passage of electrons down the chain. They soon
build up on the other side of the membrane, and
are driven back inside because of the difference
in concentration. ATP synthase uses the move-
ment of protons to produce ATP.
- B—This is an important concept to understand.
The AP examiners love this topic!
- A—Lactic acid fermentation occurs in human
muscle cells when oxygen is not available. Answer
choice B would be incorrect because alcohol fer-
mentation occurs in yeast, fungi, and some bac-
teria. During exercise, if your muscle becomes
starved for oxygen, glycolysis will switch over to
fermentation. The pain from the cramp is due to
the acidity in the muscle caused by the increased
concentration of lactate.
4. B—Glycolysis occurs in the cytoplasm. All the
other statements are correct.
5. B
6. D
7. E
8. C
9. D—A glucose molecule can net 36 ATP, an
NADH molecule can net 3, an FADH 2 molecule
can net 2, and a pyruvate molecule can net 15.
- D—During glycolysis, a glucose molecule pro-
duces 2 ATP, 2 NADH, and 2 pyruvate. The
2 pyruvate then go on to produce 8 NADH,
2 FADH 2 , and 2 ATP during the Krebs cycle to
give the total listed in answer choice D.
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