Cellular Metabolism Quizzes: Master Cell Energy Production and Regulation

Question 1

Which molecule serves as the ultimate acceptor of electrons in the electron transport chain?

Accepted Answer

Oxygen

Answer

Carbon dioxide

Answer

NADH

Answer

FADH2

Question 2

In which cellular organelle does the citric acid cycle (Krebs cycle) primarily occur?

Accepted Answer

Mitochondria

Answer

Cytoplasm

Answer

Ribosomes

Answer

Endoplasmic reticulum

Question 3

Which enzyme catalyzes the irreversible transformation of pyruvate to acetyl-CoA?

Accepted Answer

Pyruvate dehydrogenase

Answer

Pyruvate kinase

Answer

Lactate dehydrogenase

Answer

Alcohol dehydrogenase

Question 4

What is the name of the process by which cells break down glucose without oxygen?

Accepted Answer

Pyruvate fermentation

Answer

Glycolysis

Answer

Gluconeogenesis

Answer

Oxidative phosphorylation

Question 5

Which coenzyme participates in both glycolysis and the citric acid cycle?

Accepted Answer

NAD+

Answer

FMN

Answer

Coenzyme Q

Answer

Cytochrome c

Question 6

What is the primary function of ATP in cellular metabolism?

Accepted Answer

Provide energy for cellular processes

Answer

Store genetic information

Answer

Facilitate protein synthesis

Answer

Regulate enzyme activity

Question 7

What is the initial reaction of the Krebs cycle?

Accepted Answer

Acetyl-CoA and oxaloacetate combine to form citrate.

Answer

Citrate is converted to isocitrate.

Answer

Isocitrate is oxidized to α-ketoglutarate.

Answer

Succinyl-CoA is converted to succinate.

Question 8

Which of the following is not a product of glycolysis?

Accepted Answer

Citrate

Answer

Pyruvate

Answer

ATP

Answer

NADH

Question 9

In which organelle does the citric acid cycle take place?

Accepted Answer

Mitochondria

Answer

Cytoplasm

Answer

Nucleus

Answer

Ribosome

Question 10

What is the final electron acceptor in the electron transport chain?

Accepted Answer

Oxygen

Answer

NAD+

Answer

FAD

Answer

Carbon dioxide

Question 11

What is the primary product of oxidative phosphorylation?

Accepted Answer

ATP

Answer

NADH

Answer

FADH2

Answer

Pyruvate

Question 12

What is the ratio of ATP molecules produced to NADH molecules generated during glycolysis?

Accepted Answer

2:1

Answer

1:1

Answer

3:1

Answer

4:1

Question 13

In which cellular compartment does the conversion of pyruvate to acetyl-CoA occur?

Accepted Answer

Mitochondria

Answer

Cytoplasm

Answer

Endoplasmic reticulum

Answer

Nucleus

Question 14

Which of the following is a characteristic of anaerobic metabolism?

Accepted Answer

Low lactate production

Answer

High ATP yield

Answer

Occurrence in mitochondria

Answer

Use of oxygen as the final electron acceptor

Question 15

Explain how oxidative stress can contribute to the disruption of cellular metabolism in metabolic disorders.

Accepted Answer

Oxidative stress can modify enzymes, altering their structure and function, thereby disrupting metabolic pathways.

Answer

Oxidative stress primarily affects mitochondrial function, with limited impact on other cellular compartments.

Answer

Oxidative stress is solely a consequence of metabolic disorders and does not contribute to their development.

Answer

Oxidative stress does not have any significant impact on cellular metabolism.

Question 16

During glycolysis, which intermediate is oxidized to form NADH?

Accepted Answer

Phosphoglyceraldehyde

Answer

Pyruvate

Answer

Glucose-6-phosphate

Answer

1,3-bisphosphoglycerate

Question 17

Which enzyme catalyzes the irreversible conversion of isocitrate to α-ketoglutarate in the Krebs cycle?

Accepted Answer

Isocitrate dehydrogenase

Answer

Citrate synthase

Answer

Aconitase

Answer

Succinyl-CoA synthetase

Question 18

What is the primary function of oxidative phosphorylation in cellular respiration?

Accepted Answer

Generate ATP

Answer

Reduce NADH and FADH2

Answer

Produce water

Answer

Break down glucose

Question 19

Which of the following is NOT a component of the electron transport chain?

Accepted Answer

ATP synthase

Answer

Cytochrome c

Answer

Coenzyme Q

Answer

NADH dehydrogenase

Question 20

What is the final electron acceptor in the electron transport chain?

Accepted Answer

Oxygen

Answer

Hydrogen

Answer

Carbon dioxide

Answer

Water

Question 21

Which hormone stimulates the breakdown of glycogen in the liver to release glucose into the bloodstream?

Accepted Answer

Glucagon

Answer

Insulin

Answer

Epinephrine

Answer

Testosterone

Question 22

What is the primary energy currency of the cell?

Accepted Answer

ATP

Answer

Glucose

Answer

NADH

Answer

Pyruvate

Question 23

Which of the following is a characteristic of anaerobic glycolysis?

Accepted Answer

Production of lactate

Answer

High ATP yield

Answer

Requires oxygen

Answer

Produces more NADH than aerobic glycolysis

Question 24

Which enzyme catalyzes the rate-limiting step in the Krebs cycle?

Accepted Answer

α-ketoglutarate dehydrogenase

Answer

Citrate synthase

Answer

Isocitrate dehydrogenase

Answer

Succinyl-CoA synthetase

Question 25

Which product is NOT generated during glycolysis?

Accepted Answer

Acetyl-CoA

Answer

Pyruvate

Answer

ATP

Answer

NADH

Question 26

What is the primary function of the Krebs cycle?

Accepted Answer

To produce high-energy molecules (NADH and FADH2)

Answer

To synthesize glucose

Answer

To break down fatty acids

Answer

To generate ATP directly

Question 27

Which substance is the final electron acceptor in the electron transport chain?

Accepted Answer

Oxygen

Answer

NAD+

Answer

FAD

Answer

Carbon dioxide

Question 28

By which mechanism is ATP primarily synthesized during oxidative phosphorylation?

Accepted Answer

Chemiosmosis

Answer

Substrate-level phosphorylation

Answer

Photophosphorylation

Answer

Glycolysis

Question 29

What is the name of the metabolic pathway that converts fatty acids into acetyl-CoA, allowing them to enter the Krebs cycle?

Accepted Answer

Beta-oxidation

Answer

Glycolysis

Answer

Citric acid cycle

Answer

Pentose phosphate pathway

Question 30

Which enzyme plays a key role in regulating the rate of glycolysis by catalyzing an irreversible step?

Accepted Answer

Phosphofructokinase

Answer

Pyruvate kinase

Answer

Hexokinase

Answer

Cytochrome oxidase

Question 31

Which molecule serves as the primary energy currency within cells, providing energy for cellular processes?

Accepted Answer

ATP

Answer

Glucose

Answer

Pyruvate

Answer

NADH

Question 32

Which characteristic is unique to oxidative phosphorylation, distinguishing it from other metabolic processes?

Accepted Answer

It requires the presence of oxygen

Answer

It generates a large amount of ATP

Answer

It occurs in the cytoplasm of the cell

Answer

It is stimulated by cyanide

Question 33

What is the primary function of the mitochondrial inner membrane in cellular respiration?

Accepted Answer

To establish and maintain a proton gradient

Answer

To synthesize ATP directly

Answer

To transport electrons

Answer

To produce NADH and FADH2

Question 34

Identify the initial step in the glycolysis pathway:

Accepted Answer

Phosphorylation of glucose

Answer

Isomerization of glucose-6-phosphate to fructose-6-phosphate

Answer

Cleavage of fructose-1,6-bisphosphate

Answer

Oxidation of glyceraldehyde-3-phosphate

Question 35

In the electron transport chain, what is the primary role of NADH and FADH2?

Accepted Answer

Electron donors

Answer

Electron acceptors

Answer

Proton pumps

Answer

ATP generators

Question 36

Which enzyme catalyzes the conversion of pyruvate to acetyl-CoA, a crucial step in the Krebs cycle?

Accepted Answer

Pyruvate dehydrogenase

Answer

Citrate synthase

Answer

Isocitrate dehydrogenase

Answer

α-Ketoglutarate dehydrogenase

Question 37

What is the primary purpose of oxidative phosphorylation?

Accepted Answer

ATP synthesis

Answer

NADH and FADH2 generation

Answer

Proton pumping

Answer

Krebs cycle regulation

Question 38

The Cori cycle primarily facilitates:

Accepted Answer

Lactate transport from muscle to liver

Answer

Glucose transport from liver to muscle

Answer

ATP-ADP balance regulation

Answer

Ketone body formation

Question 39

What is the major metabolic fate of acetyl-CoA?

Accepted Answer

Oxidation in the Krebs cycle

Answer

Fatty acid synthesis

Answer

Cholesterol synthesis

Answer

Urinary excretion

Question 40

Which of the following is the principal substrate for cellular respiration, initiating the metabolic breakdown of glucose?

Accepted Answer

Glucose

Answer

Fatty acids

Answer

Amino acids

Answer

Ketone bodies

Question 41

What is the approximate net yield of ATP molecules generated from the complete oxidation of one molecule of glucose through cellular respiration?

Accepted Answer

36-38

Answer

2

Answer

68

Answer

120

Question 42

Which enzyme catalyzes the pivotal conversion of pyruvate to acetyl-CoA, a key step in the transition from glycolysis to the Krebs cycle?

Accepted Answer

Pyruvate dehydrogenase

Answer

Citrate synthase

Answer

Isocitrate dehydrogenase

Answer

α-Ketoglutarate dehydrogenase

Question 43

What is the primary function of the electron transport chain in cellular metabolism?

Accepted Answer

To generate a proton gradient across the mitochondrial inner membrane

Answer

To produce NADH and FADH2

Answer

To convert acetyl-CoA to citrate

Answer

To reduce oxygen to water

Question 44

What is the primary cause of lactic acid accumulation in skeletal muscle during intense exercise, contributing to muscle fatigue and soreness?

Accepted Answer

Insufficient oxygen supply

Answer

Inadequate glycogen reserves

Answer

Mitochondrial malfunction

Answer

Elevated pyruvate concentrations

Question 45

Which metabolic disorder is characterized by a deficiency or dysfunction of pyruvate dehydrogenase, impairing the conversion of pyruvate to acetyl-CoA?

Accepted Answer

Lactic acidosis

Answer

Type 1 diabetes

Answer

Mitochondrial myopathy

Answer

Fatty acid oxidation disorder

Question 46

What is the primary role of carnitine in cellular metabolism, particularly in relation to fatty acid utilization?

Accepted Answer

To transport fatty acids into the mitochondria for oxidation

Answer

To export acetyl-CoA from the mitochondria to the cytosol

Answer

To generate NADH in the cytosol

Answer

To regulate the activity of the Krebs cycle

Question 47

A patient presents with a deficiency in pyruvate dehydrogenase. Which of the following metabolic processes would be specifically impaired?

Accepted Answer

Conversion of pyruvate to acetyl-CoA

Answer

Glycolysis

Answer

Krebs cycle

Answer

Gluconeogenesis

Question 48

Which of the following enzymes is the primary regulatory step in glycolysis?

Accepted Answer

Phosphofructokinase-1 (PFK-1)

Answer

Glucose-6-phosphatase

Answer

Hexokinase

Answer

Pyruvate kinase

Question 49

A patient with a mitochondrial disorder exhibits impaired oxidative phosphorylation. Which cellular process would be directly affected?

Accepted Answer

ATP production

Answer

NADH regeneration

Answer

Fatty acid synthesis

Answer

Glycogenolysis

Question 50

During prolonged fasting, the body primarily relies on which metabolic pathway for energy production?

Accepted Answer

Beta-oxidation of fatty acids

Answer

Protein catabolism

Answer

Glycolysis

Answer

Gluconeogenesis

Question 51

Which of the following is NOT a product of the Krebs cycle?

Accepted Answer

Glucose

Answer

ATP

Answer

NADH

Answer

FADH2

Question 52

The electron transport chain generates a proton gradient. What is the primary purpose of this gradient?

Accepted Answer

ATP synthesis via ATP synthase

Answer

Electron transport

Answer

Proton pumping

Answer

Heat production

Question 53

A deficiency in carnitine palmitoyltransferase-1 (CPT-1) would primarily affect which of the following?

Accepted Answer

Fatty acid entry into mitochondria for beta-oxidation

Answer

ATP production

Answer

Amino acid metabolism

Answer

Glucose metabolism