Practice Question For Chap 6 & Chap 7

Question 1

When is oxygen used in cellular respiration?

Answer 1

As the final electron acceptor in the electron transport chain.

Question 2

What happens to pyruvate after glycolysis in the absence of oxygen?

Answer 2

It undergoes fermentation to produce either lactic or ethanol

Question 3

What are the two main types of fermentation, and what are their end products?

Answer 3

Alcohol fermentation (ethanol) and lactic acid fermentation (lactic acid)

Question 4

Which stage of cellular respiration directly requires oxygen?

Answer 4

Electron transport chain

Question 5

How does the formation of a proton gradient drive ATP production in the mitochondria?

Answer 5

Protons move down their concentration gradient through ATP synthase, which powers the synthesis of ATP

Question 6

What is the total ATP yield from glycolysis per one molecule of glucose?

Answer 6

2 ATP

Question 7

What is the role of oxygen in the electron transport chain?

Answer 7

To accept electrons and combine with protons a to form water

Question 8

Which of the following reactions is Endergonic?

Answer 8

ATP synthesis from ADP and Pi
(inorganic phosphate)

Question 9

How many ATP molecules are generated per glucose molecule in the electron transport chain(oxidative phosphorylation).

Answer 9

28-30 ATP

Question 10

What goes into glycolysis, and what come out?

Answer 10

In: 1 glucose, 2 NAD+, 4 ADP + P (phosphate group)

Out: 2 pyruvate, 2 NADH, 4 ATP
(net 2 ATP)

ATP is formed glycolysis by substrate-level phosphorylation.

Question 11

What enters pyruvate oxidation, and what is produced?

Answer 11

In: 2 pyruvate, 2 NAD+, 2 CoA (coenzyme A)
Pyruvate enters a series of redox reactions

Out: 2 acetyl-CoA, 2 NADH, 2 CO2

Question 12

What enters the citric acid cycle, and what comes out?

Answer 12

In: 2 acetyl-CoA, 6 NAD+, 2 FAD, 2 ADP + P

Out: 4 CO2, 6 NADH, 2 FADH2, 2 ATP or ( GTP)

Question 13

What goes into the electron transport chain, and what comes out?

Answer 13

In: 10 NADH, 2 FADH2, O2, ADP + P

Out: 28-30 ATP, H2O, NAD+, FAD

Question 14

What is required for ATP synthesis via oxidative phosphorylation, and what are the products?

Answer 14

In: ADP + P , H+ gradient (proton gradient), O2

Out: ATP, H2O

Question 15

What goes into lactic acid fermentation, and what comes out?

Answer 15

In: 2 pyruvat, 2 NADH

Out: 2 lactate, 2 NAD+

Question 16

What goes into alcohol fermentation, and what is produced?

Answer 16

In: 2 pyruvate, 2 NADH

Out: 2 ethanol, 2 CO2, 2 NAD+

Question 17

What enters the light reactions of photosynthesis, and what come out?

Answer 17

In: light energy, H2O, NADP+, ADP + P

Out: O2, ATP, NADPH

Question 18

What goes into the Calvin cycle (dark reactions) and what comes out?

Answer 18

In: CO2, ATP, NADPH

Out: G3P ( a 3- carbon sugar), ADP+ P, NADP+

Question 19

What are the inputs and outputs of the entire cellular respiration process (combining stages)?

Answer 19

In: 1 glucose, 6 CO2

Out: 6 CO2, 6 H2O, - 32-34 ATP

Question 20

True/False
Glycolysis occurs in the mitochondria of eukaryotic cells.

Answer 20

False (glycolysis occurs in the cytoplasm )

Question 21

True/False
In the absence of oxygen, cells can undergo fermentation to produce ATP.

Answer 21

True

Question 22

Pyruvate must be converted into acetyl-CoA before it can enter the citric acid cycle.

Answer 22

True

Question 23

True/False
Oxygen is used directly during glycolysis to break down glucose.

Answer 23

False (Oxygen is not required in glycolysis; it is used in the electron transport chain.)

Question 24

True/False
The electron transport chain creates a proton gradient across the mitochondrial membrane, which drives ATP production.

Answer 24

True

Question 25

True/False
Fermentation produces more ATP than aerobic respiration

Answer 25

False
(Fermentation produces far less ATP than aerobic respiration, which can yield around 32-34 ATP per glucose molecule).

Question 26

True/False
Carbon dioxide is produced during both pyruvate oxidation and the citric acid cycle

Answer 26

True

Question 27

True/False
The total ATP yield from glycolysis is 4 ATP, but the net gain is 2 ATP.

Answer 27

True

Question 28

True/False
The final electron acceptor in the electron transport chain is oxygen, which forms water

Answer 28

True

Question 29

True/False
The citric acid cycle directly uses oxygen to oxidize acetyl-CoA

Answer 29

False
( the citric acid cycle does not use oxygen directly; oxygen is only involved at the electron transport chain)

Question 30

What are the three main stages of cellular respiration, and where do they occur in eukaryotic cells?

Answer 30

• Glycolysis: occurs in the cytoplasm
• Pyruvate oxidation and the citric acid cycle: occurs in the mitochondrial matrix
• Oxidative phosphorylation (electron transport chain and Chemiosmosis): occurs in the inner mitochondrial membrane

Question 31

What is the primary purpose of glycolysis, and what are the main products?

Answer 31

The purpose of glycolysis is to break down glucose ( 6- carbon molecule) into two molecules of pyruvate (3-carbon molecules). The main products are:

• 2 ATP (net gain)
• 2 NADH
• 2 pyruvate

Question 32

During pyruvate oxidation, what happens to pyruvate before it enters the citric acid cycle?

Answer 32

Pyruvate is converted into acetyl-CoA. This process involves the removal of one carbon (released as CO2), reduction of NAD+ to NADH, and the addition of coenzyme A to form acetyl-CoA.

Question 33

What goes into the citric acid cycle, and what comes out?

Answer 33

In;
- 2 acetyl-CoA
- 6 NAD+
- 2 FAD
- 2 ADP + P

Out;
- 4 CO2
- 6 NADH
- 2 FADH2
- 2 ATP

Question 34

Explain the role of the electron transport chain (ETC) in oxidative phosphorylation.

Answer 34

The electron transport chain ETC consists of protein complexes embedded in the inner mitochondrial membrane. Electrons from NADH and FADH2 are transferred through these complexes, releasing energy. Thus energy is used to pump protons (H+) from the mitochondrial matrix into the Intermembrane space, creating a proton gradient.

Question 35

What is Chemiosmosis, and how does it contribute to ATP production?

Answer 35

Chemiosmosis is the process by which protons flow down their concentration gradient from the Intermembrane space back into the mitochondrial matrix through the enzyme ATP synthase. This flow of protons drives the production of ATP from ADP and inorganic phosphate.