Deck 4: Metabolism

Question 1

Metabolism refers to

A) synthesis of larger molecules only
B) breakdown of larger molecules into smaller ones only
C) energy producing reactions only
D) all chemical reactions in the body

Answer 1

D

Question 2

Which of the following is NOT an example of anabolic reaction?

A) translation
B) synthesis of membrane phospholipids
C) digestion of triglycerides in digestive tract
D) DNA replication

Answer 2

C

Question 3

Enzymes which remove water from the cellular substrates are called

A) oxidases
B) kinases
C) proteases
D) anhydrases

Answer 3

D

Question 4

Body biochemistry is a highly orchestrated process of reaction coupling between exergonic and endergonic reactions. Which example best illustrates the concept of reaction coupling?

A) storage of extra amino acids from food as "love handles" fat
B) recovery of glucose from glycogen in the liver cells
C) transport of cholesterol in the form of LDLs and HDLs
D) breakdown of glucose in glycolysis and Krebs cycle

Question 5

Enzymes are cellular catalysts because they

A) are products of cellular synthesis
B) help substrates to interact
C) are broken down in chemical reactions
D) increase the probability of contact between molecules

Question 6

Kinetic energy is associated with

A) fundamental energy of all particles that stay in motion
B) storage of energy due to elevation of the object
C) energy of chemical bonds in complex molecules
D) the destructive force of energy

Question 7

Brownian motion is the random movement of molecules suspended in a liquid or a gas. What type of energy makes these molecules move?

A) chemical energy
B) kinetic energy
C) potential energy
D) conversion of energy

Question 8

When biochemists are talking about the coupling of the chemical reactions they are referring to

A) a chain of catabolic reactions
B) substrate availability for reactions that produce macromolecules
C) exergonic reactions providing energy for endergonic reactions
D) reactions that happen in the same location within the cell

Question 9

Which of the following enzymes removes water from carbonic acid to produce CO₂ (and of course H₂O)?

A) carbonic hydroxylase
B) carbonic anhydrase
C) carbonic synthase
D) carbonic kinase

Question 10

? If a chemical reaction, such as ATP hydrolysis, releases energy to the surroundings it is called

A) endergonic
B) exergonic
C) energetically balanced
D) reversible

Question 11

What is the best definition of exergonic reactions?

A) they absorb more energy than they release
B) they release more energy than they absorb
C) they are typically anabolic reactions
D) they often combine smaller molecules to larger molecules

Question 12

What characteristic links the reactions of synthesis of phospholipids and translation of new proteins?

A) they are both catabolic
B) they are both endergonic
C) they are both exergonic
D) they have no linking characteristics

Question 13

Endergonic reactions

A) absorb more energy than they release
B) release more energy than they absorb
C) are typically catabolic reactions
D) often breakdown larger molecules to smaller molecules

Question 14

Chemical energy is associated with

A) atoms in motion
B) bonds in chemical compounds
C) conversion of different forms of energy
D) creation of gradients

Question 15

Anabolic reactions are the reactions that

A) break larger molecules to smaller molecules
B) form larger molecules from smaller molecules
C) involve any type of organic molecules
D) take place exclusively in muscle cells

Question 16

Enzymes are molecules that

A) raise the activation energy of the reactions
B) are ligands for reaction's substrates increase substrate concentration
C) supply energy for the reaction
D) accelerate chemical reactions

Question 17

Activation of glycogen phosphorylase, an enzyme that catalyzes breakdown of glycogen, relies on the attachment of a high energy phosphate group from ATP to that enzyme aka phosphorylation. Enzymes which attach phosphate groups to molecules are called

A) oxidases
B) kinases
C) lipases
D) anhydrases

Question 18

People often tell Jane she has a very "good" metabolism; she seems not to gain weight no matter what she eats. What reactions of metabolism are most likely dominant in Jane's body?

A) anabolic
B) catabolic
C) endergonic
D) synthesis

Question 19

Which of the following is an example of a catabolic reaction?

A) breakdown of protein to amino acids
B) conversion of fatty acids into triglycerides
C) synthesis of glycogen from glucose
D) assembly of polypeptide chain from amino acids

Question 20

An example of a catabolic reaction could be

A) formation of peptide bonds between amino acids
B) conversion of triglycerides to fatty acids and glycerol
C) synthesis of glycogen from glucose
D) assembly of nucleotides into a DNA string

Question 21

The optimal pH for enzymes is

A) always near pH 7.4
B) pH value when the reaction rate is greatest
C) pH when the enzyme starts to denature
D) pH value when all enzymes are occupied by substrates

Question 22

The optimal temperature for enzymes is described as

A) equal to body temperature
B) when the reaction rate is maximal
C) when the enzymes start to denature
D) when the enzymes are saturated

Question 23

The main molecule that stores and transfers energy between exergonic and endergonic reactions in the cell is

A) ATP
B) cAMP
C) FAD
D) NADH

Question 24

What metabolic pathway uses substrate level phosphorylation to make ATP?

A) gluconeogenesis
B) glycogenolysis
C) glycogenesis
D) glycolysis

Question 25

The protein that you have purified in your biochemistry lab seems to "change" D-glucose, but not L-glucose, to glucose-6-phosphate. You suppose it is one of the hexokinase isoforms. Which property of the enzyme is responsible for the result you have just seen?

A) enzyme allosteric inhibition
B) enzyme substrate specificity
C) enzyme temperature dependence
D) lack of cofactor for that enzyme

Question 26

Only about 40% of energy released in the catabolism of food is used for cellular functions, the rest is lost as heat. Which diet makes more efficient use of sun energy captured in chemical bonds during photosynthesis?

A) Paleo diet
B) mixed diet including meat
C) primarily meat diet
D) vegetarian diet

Question 27

Rate of enzymatic reactions is influenced by

A) temperature only
B) concentrations of reactants only
C) both temperature and concentration of reactants
D) None of the choices is correct, rate of the enzymatic reaction is constant.

Question 28

Substrate-level phosphorylation involves the following steps

A) chemi-osmosis
B) transfer of a phosphate group by an enzyme
C) transport of electrons
D) breakdown of molecular oxygen, O₂

Question 29

What are the advantages of metabolic pathways in the cells?

A) Cells can speed up the reactions to maximize use of substrates until they are all "used up".
B) Cells use less energy when the reaction happens in multiple steps rather than single one.
C) When products are not used up and therefore accumulate in cells, cells can shut down the pathway.
D) Many enzymes involved in intermediate steps the metabolic pathway decrease probability of mutations.

Question 30

Which statement correctly describes the process of oxidative phosphorylation in human cells?

A) it is a process of ATP production in aerobic conditions
B) it can proceed both in the presence and absence of oxygen
C) phosphate group is transferred to ADP from phosphorylated intermediate
D) phosphate group is oxidized to ATP and inorganic phosphate

Question 31

ATP, a major energy storing molecule in the cell, can be produced in the process(es) of

A) oxidative phosphorylation only
B) substrate level phosphorylation only
C) both in substrate level and oxidative phosphorylation
D) dephosphorylation of ADP

Question 32

Enzymes are proteins that often use cofactors to speed up chemical reactions. What types of molecules are usually cofactors in enzymatic reactions?

A) ions
B) vitamins
C) both ions and vitamins
D) None of the choices is correct. Cofactors are always proteins.

Question 33

When food molecules, such as fats and carbohydrates, are broken to CO₂ and water, and the energy accumulated in their chemical bonds recovered, the energy is temporarily stored in an ______ molecule before it can be used in cellular work.

A) adenosine biphosphate
B) adenosine triphosphate
C) adenine triphosphate
D) adenine monophosphate

Question 34

Why is 37^o the optimal temperature for enzymatic reactions for most human enzymes?

A) It is the temperature when enzymatic pocket gets wider and the kinetic energy of molecules is at its maximum.
B) It is the temperature when kinetic energy of molecules is at its maximum; above this temperature kinetic energy decreases due to collisions.
C) It is the temperature when the molecules have high kinetic energy but the enzyme does not lose its 3D structure yet.
D) It is the temperature when cofactors best bind to the enzymes and increase activation energy.

Question 35

Substrate-level phosphorylation takes place in

A) cytosol only
B) mitochondria only
C) both cytosol and mitochondria
D) only in the vesicles

Question 36

In physiology, we often talk about metabolic pathways such as glycolysis, gluconeogenesis or cholesterol synthesis. What is the best description of metabolic pathway?

A) any reaction that has two or more reactants
B) an enzymatic reaction involving binding of substrates to the active site of the enzyme
C) a chain of reactions in the cell where activation energy increases from step to step
D) a sequence of reactions that use products from the previous step as substrates for the next

Question 37

A "normal", not deionized water was used in the experiment that included an enzymatic reaction. The experiment did not work as expected. What is the MOST LIKELY reason for the failure?

A) The "normal" water used in the experiment contained ions that interacted with the enzyme activity.
B) Deionized water is usually warmer, and the experimenter forgot to heat up the water from the "normal" faucet.
C) Deionized water most likely gave the false positive result due to lack of ions.
D) "Normal" water gave false negative results due to lack of necessary ions that deionized water has.

Question 38

ATP (adenosine triphosphate) is

A) a protein
B) an enzyme
C) a nucleotide
D) a phospholipid

Question 39

Imagine being a research scientist who plans an experiment that includes an enzymatic reaction. What conditions of the experiment are critical for optimum performance?

A) temperature of the reaction
B) pH of the buffer
C) chemical composition of the medium in which the reaction is performed
D) All of the choices are correct.

Question 40

When working with enzymes in laboratory, aka in vitro, researchers increase the temperature from room temperature to 37^o Celsius. What is one justification for that action?

A) Higher temperature increases activation energy of the reaction.
B) Higher temperature increases kinetic energy of substrates.
C) Higher temperature decreases probability of spontaneous reaction.
D) Higher temperature inactivates the enzymes.

Question 41

Which of the following statements best describes glycolysis?

A) glycolysis occurs in the cytosol
B) glycolysis produces more molecules of ATP than does oxidative phosphorylation
C) glycolysis converts glucose into glycogen
D) glycolysis is a main pathway for fatty acid oxidation

Question 42

The final step of the cellular respiration process in which the electrons are passed to oxygen is

A) glycolysis
B) Krebs cycle
C) transfer of electrons in the electron transport chain
D) ATP synthesis by ATP synthase

Question 43

In aerobic conditions pyruvic acid, the product of glycolysis, is transported and metabolized (oxidized) to CO₂ and H₂O. Where does this process take place?

A) cytosol
B) lysosome
C) mitochondria
D) peroxisome

Question 44

Glycogen is a

A) polysaccharide
B) disaccharide
C) monosaccharide
D) glycoprotein

Question 45

Glucose is labeled with radioactive 14C and followed as it is oxidized to CO₂ and H₂0 in a mammalian liver cell. During this process the radioactive labeling will be detectable in?

A) mitochondria only
B) first in the nucleus, then in the mitochondria
C) first in the mitochondria then on the ribosomes
D) first in the cytoplasm then in the mitochondria

Question 46

A nutritional deficiency of niacin will manifest itself with

A) higher energy requirements of the cell
B) lower energy availability for the cell
C) higher energy output of the cell
D) loss of cellular energy in the form of heat

Question 47

Pyruvate kinase deficiency is a genetic condition resulting from a mutation in the gene coding for one of the enzymes of glycolysis, pyruvate kinase. It mostly affects red blood cells, and leads to irregular morphology of red blood cells and hemolytic anemia. Yet, pyruvate kinase is present in all cells where it catalyzes one step of glycolysis. Which of the following best explain why red blood cells are MOST affected in this disorder?

A) Defect of glycolysis enzyme leads to lower levels of ATP in red blood cells.
B) Red blood cells exclusively rely on glycolysis as their ATP source.
C) Red blood cells cannot produce ATP from beta oxidation of fatty acids.
D) All of the choices are correct.

Question 48

KCN (potassium cyanide) blocks the mitochondrial cytochrome c-oxidase (one of the complexes in electron transport chain). What would this most likely do?

A) encourage NADH production and speed up ATP production
B) inhibit electron transport and create more Co-enzyme Q
C) encourage cellular respiration and therefore production of more ATP
D) inhibit aerobic respiration and therefore decrease production of ATP

Question 49

What is the only component of the electron transport chain that is NOT a protein?

A) cytochrome c
B) cytochrome b
C) coenzyme Q
D) flavoprotein

Question 50

What is the net ATP gain after a single round of glycolysis (breakdown of one molecule of glucose)?

A) 1 ATP molecule
B) 2 ATP molecules
C) 3 ATP molecules
D) 30-32 ATP molecules

Question 51

When body activities require ATP, glucose can be retrieved from glycogen stores and used in ATP production. If the liver's glycogen stores are low you need to eat to provide more substrates for ATP synthesis. Which of the following processes happen if you are fasting in order to lose weight?

A) glycogenesis
B) gluconeogenesis
C) triglyceride conversion to glucose
D) lipogenesis

Question 52

If you have done the immunocytochemistry with fluorescently labeled antibodies against Krebs cycle enzymes, where in the cell would you expect to find fluorescence?

A) all over the cell
B) in the mitochondrial outer membrane only
C) in the mitochondrial matrix
D) in the nucleus

Question 53

Which process requires obligatory presence of oxygen during ATP production in human cells?

A) substrate level phosphorylation
B) oxidative phosphorylation
C) both oxidative and substrate level phosphorylation
D) None of the choices is correct.

Question 54

In aerobic conditions pyruvic acid, the product of glycolysis, is transported and metabolized (oxidized) to CO₂ and H₂O. This takes place in the ______.

Question 55

The majority of ATP in eukaryotic cells is synthesized in

A) cytoplasm
B) endoplasmic reticulum
C) mitochondria
D) lysosomes

Question 56

The formation of glucose molecules from non-carbohydrate precursors is called

A) glycogenesis
B) glycogenolysis
C) glycolysis
D) gluconeogenesis

Question 57

What process of ATP production will still proceed normally in people with mitochondrial dysfunction diseases?

A) substrate level phosphorylation
B) oxidative phosphorylation
C) chemi-osmosis
D) electron transport chain

Question 58

Which two vitamins are necessary for the formation of NAD⁺ and FAD?

A) niacin and riboflavin
B) thiamin and folic acid
C) niacin and cyanocobalamin
D) thiamin and biotin

Question 59

Before a marathon, many athletes "carb load" to increase their endurance. The excess of carbohydrates they consume is stored in the body until it is needed to create ATP. Which of the following most accurately describes the process of "carb loading"?

A) Extra carbohydrates are stored as triglycerides in the adipose tissue until they are converted back to glucose to create ATP.
B) Extra carbohydrates are stored as glycogen in the muscle and liver and converted to ATP during the exercise.
C) Extra carbohydrates are metabolized to proteins and stored in the muscle, and later converted to glucose to create ATP.
D) Extra carbohydrates are stored as lactic acid until they are converted back to glucose and used to create ATP.

Question 60

Hydrogen atoms are carried by NADH + H⁺ and FADH₂ to the

A) ATP molecule
B) ADP molecule
C) electron transport chain
D) ATP synthase

Question 61

Proteins are building blocks of our bodies and workhorses behind most of the cellular activities. Proteins can also be catabolized to provide energy. What conditions increase protein catabolism?

A) high availability of glucose
B) low availability of glucose
C) low availability of oxygen
D) high blood pH

Question 62

During a heart attack, blood flow, and therefore oxygen delivery, to the heart muscle is interrupted. How would it change the metabolism of the heart muscle?

A) the rate of lactic acid production would go down
B) the use of glucose in heart muscle would decrease
C) oxidative phosphorylation would slow down
D) All of the choices are correct.

Question 63

High protein, low carbohydrate diets are a rave in food advertising. Excess of dietary proteins over what the body needs for growth and repair will result in

A) muscle building
B) weight loss
C) increased body fat
D) increased endurance

Question 64

This water-soluble vitamin is critical to DNA and RNA synthesis, and should be included in the prenatal vitamins, because its deficiency can cause birth defects such as spina bifida.

A) vitamin K
B) niacin
C) folate
D) vitamin C
E) biotin

Question 65

John has been on a low carbohydrate diet for a while and he's started smelling "funny" even if he takes a shower. His urine analysis showed the presence of ketones in his urine. What processes are most likely running in his body?

A) higher than normal beta oxidation
B) higher than normal lipogenesis
C) lower than normal lipolysis
D) lower than normal gluconeogenesis

Question 66

This water-soluble vitamin functions as an antioxidant, removing free radicals inhaled as a result of smog, car fumes or cigarette smoke.

A) vitamin K
B) niacin
C) folic acid
D) vitamin C

Question 67

Excessive dietary intake of carbohydrates, but not amino acids, leads to formation of triglycerides.

Question 68

Protein anabolism

A) is also called transcription
B) includes peptide bond formation
C) requires transamination of amino acids
D) is possible only in muscles

Question 69

Lipogenesis uses ____ to make triglycerides

A) fatty acids
B) glycerol
C) amino acids
D) All of the choices are correct.

Question 70

Vitamins are organic compounds that

A) play supportive role in metabolism as coenzymes
B) are the energy source
C) when metabolized produce heat
D) have to be taken as supplements

Question 71

Lipolysis is the process of

A) forming acetyl CoA
B) anabolism of fatty acid
C) catabolism of triglycerides
D) making triglycerides from carbohydrates

Question 72

Catabolism of amino acids begins with a removal amino groups. This process, also known as deamination

A) occurs in the liver
B) produces ammonia
C) leads to production of urea
D) All of the choices are correct.

Question 73

Which of the following slogans about the vitamins is(are) a myth(s)?

A) If little is good, then a lot is better
B) Vitamins are great energy sources.
C) All vitamins can be supplied by green leafy veggies.
D) All of the choices are myths.

Question 74

Proteins are macromolecules that are synthesized based on the template of mRNA. If an essential amino acid lysine was missing in the diet, and was necessary for synthesis of a new protein

A) it would be replaced with another available amino acid
B) protein synthesis would stop and wait for lysine
C) it would be pulled from other protein to build the new one
D) liver will produce it from glucose

Question 75

Lipogenesis is the process of

A) beta oxidation of fatty acids
B) fatty acid catabolism
C) forming triglycerides from carbohydrates
D) forming of glycerol and fatty acids from triglycerides

Question 76

A keto acid is a product of

A) synthesis of essential amino acids
B) oxidative phosphorylation
C) anabolism of amino acids
D) deamination reaction

Question 77

This fat-soluble vitamin protects phospholipid bilayers from oxidative damage (functions as antioxidant).

A) vitamin K
B) niacin
C) folic acid
D) vitamin E

Question 78

Amino acid catabolism begins with

A) peptide bond formation
B) deamination
C) ketosis
D) transamination

Question 79

Catabolism of fatty acids begins with

A) ketogenesis
B) beta oxidation
C) lipolysis
D) lipogenesis

Question 80

What cells are responsible for converting excess of dietary glucose to triglycerides?

A) hepatocytes only
B) adipocytes only
C) hepatocytes and adipocytes
D) All cells can convert excess of glucose to triglycerides.