slide 10

Question 1

The citric acid cycle completes

Answer 1

the energy-yielding
oxidation of organic molecules (breakdown of
pyruvate) when oxygen is present

Question 2

The citric acid cycle takes place in

Answer 2

the mitochondria

Question 3

The citric acid cycle has 8 steps

Answer 3

each catalyzed by

a specific enzyme.

Question 4

Before the citric acid cycle can begin pyruvate must first

Answer 4

bind to coenzyme A and become acetyl coenzyme A

acetyl CoA

Question 5

The citric acid cycle produces

Answer 5

NADH from NAD+
and a related molecule FADH2
from FAD+.

Question 6

NADH from NAD+
and a related molecule FADH2
from FAD+.

Answer 6

Both molecules are used in cellular respiration to

transport high energy electrons between reactions.

Question 7

Citric Acid Cycle

Answer 7

Loss of 2 carbon per cycle
(4 per glucose) –
conversion to CO2
3 NADH made per cycle
(6 per glucose)
1 FADH2 made per cycle
(2 per glucose)
1 ATP made per cycle
(2 per glucose)
CoA regenerated

Question 8

Oxidative phosphorylation has two components:

Answer 8

the

electron transport chain and chemiosmosis

Question 9

Following glycolysis and the citric acid cycle, NADH and

FADH2 account for most of the energy extracted from food

Answer 9

These two electron carriers donate electrons to the electron
transport chain, which allows ATP synthesis via
chemiosmosis.

Question 10

Oxidative phosphorylation

Answer 10

is a series of redox reactions

across the inner membrane of the mitochondria.

Question 11

The electron transport chain is

comprised

Answer 11

of multiprotein
complexes spanning the inner
mitochodrial membrane

Question 12

ELECTRON TRANSPORT CHAIN
The carriers alternate reduced
and oxidized states as they
accept and donate electrons

Answer 12

Electrons drop in free energy as
they go down the chain and are
finally passed to O2
, forming H2O.

Question 13

The electron transport chain produces no ATP directly

Answer 13

At certain steps along the electron transport chain electron
transfer causes protein complexes to pump H+
from the
mitochondrial matrix to the intermembrane space.

Question 14

ELECTRON TRANSPORT CHAIN

The resulting H+ gradient

Answer 14

– Stores energy
– Is referred to as a proton-motive force
– Drives chemiosmosis

Question 15

Chemiosmosis

Answer 15

ATP synthase is the enzyme

that makes ATP

Question 16

ATP synthase uses the H+

gradient

Answer 16

established by the
electron transport chain to
drive ATP synthesis

Question 17

During respiration, most energy flows in this sequence:

Answer 17

• Glucose
• NADH, FADH2
• electron transport chain
• proton gradient
• ATP

Question 18

ATP synthesis has a high efficiency among reactions.

Answer 18

About 40% of the energy in a glucose molecule is
transferred to ATP during cellular respiration, making
approximately 32 ATP.
The remainder of energy is lost as heat

Question 19

Alternatives to Oxidative

Phosphorylation

Answer 19

fermentation

Question 20

Fermentation

Answer 20

enables some cells to produce ATP without

the use of oxygen or an electron transport chain

Question 21

Fermentation is an extension of glycolysis

Answer 21

in which ATP

is produced only by substrate-level phosphorylation.

Question 22

Alcohol fermentation (pyruvate converted to ethanol)

Answer 22

lactic acid fermentation (pyruvate converted to lactate) are

two examples

Question 23

Catabolic pathways

Answer 23

– Funnel electrons from
many kinds of organic
molecules into cellular
respiration
– Molecules other than
glucose can feed into
cellular respiration

Question 24

Cellular respiration is a
pathway controlled by
negative feedback.

Answer 24

If ATP concentration drops,

respiration speeds up

Question 25

Cellular respiration taps
energy that was stored in
food

Answer 25

by photosynthesis