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True or False Quiz
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1
When an enzyme catalyzes a chemical reaction some of the enzyme is lost.
A)True
B)False
2
The amount of energy released by a chemical reaction is much greater when an enzyme catalyzes it.
A)True
B)False
3
An enzyme works by decreasing the activation energy of a chemical reaction.
A)True
B)False
4
The chemical reactions of living cells could not occur in the absence of enzymes.
A)True
B)False
5
A substrate molecule binds to certain amino acids that line the active site of an enzyme.
A)True
B)False
6
Hydrolases are enzymes that remove water from organic molecules (that is, remove -H and -OH chemical groups and produce water as a reaction product, known as dehydration).
A)True
B)False
7
All enzyme names end with the suffix -ase.
A)True
B)False
8
Enzymes increase the energy content of the reactants (or substrates).
A)True
B)False
9
One reason enzymes are so effective is that each enzyme can catalyze a broad range of metabolic reactions.
A)True
B)False
10
Isoenzymes are enzymes that perform the same function in different cells and have slightly different chemical structures.
A)True
B)False
11
The active sites of isoenzymes are not affected by the structural differences that distinguish one isoenzyme from another.
A)True
B)False
12
Skeletal and cardiac muscle have different forms of creatine phosphokinase.
A)True
B)False
13
The rate of an enzymatic reaction depends on the concentration of the substrate but not the concentration of the enzyme.
A)True
B)False
14
The higher the temperature, the faster the rate of an enzymatic reaction will be.
A)True
B)False
15
Human enzymes all have approximately the same temperature optimum, but highly varied pH optima.
A)True
B)False
16
Although these enzymes selectively remove phosphate groups, the phosphatase isolated from the prostate functions best at a lower pH than the phosphatase isolated from bone tissue.
A)True
B)False
17
Many enzymes cannot function when they are completely purified and isolated from their natural chemical surroundings.
A)True
B)False
18
Metal ions that aid the function of enzymes can be called either coenzymes or cofactors for those enzymes.
A)True
B)False
19
Coenzymes are organic molecules that sometimes bind to the active site of an enzyme along with its substrate in order for the enzyme to function at its optimal rate.
A)True
B)False
20
Carbonic anhydrase is an enzyme that can catalyze the breakdown of carbonic acid (H2CO3) into carbon dioxide (CO2) and water (H2O), but it cannot catalyze the reverse reaction.
A)True
B)False
21
If there is a reversible chemical reaction between two molecules A and B, and more B than A is present at a given moment, then the law of mass action predicts this reaction will go toward the left (that is, more B will be converted to A).
A)True
B)False
22
For most metabolic pathways a single enzyme catalyzes all the reactions.
A)True
B)False
23
The nine-step enzymatic conversion of glucose to pyruvic acid is a metabolic pathway. The one-step enzymatic conversion of CO2 and H2O to carbonic acid is not.
A)True
B)False
24
An intermediate in a metabolic pathway may serve as the substrate for two or more different enzymes that catalyze reactions leading in different directions.
A)True
B)False
25
Some metabolic end-products can deactivate or inhibit the very enzymes that are responsible for their production.
A)True
B)False
26
Allosteric inhibitors bind at a site other than the active site to decrease enzyme activity.
A)True
B)False
27
Suppose enzyme3 catalyzes the third step in a metabolic pathway where intermediate G is converted to intermediate H. An inborn error of metabolism resulting in a defective enzyme3 would result in a surplus of G and deficiency of H.
A)True
B)False
28
Albinism is the result of an inherited defect in an enzyme that produces skin pigment.
A)True
B)False
29
The fundamental point of cellular metabolism is to increase the amount of entropy in the system.
A)True
B)False
30
Entropy is a measure of the amount of free energy in a system.
A)True
B)False
31
Photosynthesis is an endergonic reaction.
A)True
B)False
32
The human body is unable to carry out any endergonic reactions because it does not have any photosynthetic pigments and cannot synthesize organic nutrients.
A)True
B)False
33
The complete oxidation of glucose to CO2 + H2O is an exergonic reaction.
A)True
B)False
34
The oxidation of 1 gram of glucose to CO2 + H2O will release more calories when done in small, enzymatically-controlled steps within a cell than when done in a single step by simply touching a match to a 1 gram of glucose.
A)True
B)False
35
One Calorie will raise the temperature of one liter of water one degree Celsius.
A)True
B)False
36
A cell must maintain a state of high entropy to stay alive.
A)True
B)False
37
Exergonic reactions in a cell are often directly coupled to endergonic reactions.
A)True
B)False
38
The endergonic reaction to which most exergonic reactions of a cell are linked is ATP → ADP + Pi + Energy.
A)True
B)False
39
When a molecule is reduced the molecule will gain one or more electrons.
A)True
B)False
40
Oxidation means a reaction in which some atom or molecule combines with oxygen.
A)True
B)False
41
In the course of performing its role, a reducing agent becomes oxidized.
A)True
B)False
42
It is impossible for an oxidation reaction to occur without a reduction reaction occurring simultaneously.
A)True
B)False
43
If a molecule picks up two hydrogen atoms, it becomes reduced.
A)True
B)False
44
It is possible for the same molecule to serve as both an oxidizing agent and a reducing agent, alternating between the oxidized and reduced forms.
A)True
B)False
45
The structure of the coenzyme NAD is very similar to the structure of the universal energy carrier ATP.
A)True
B)False
46
NADH is a reducing agent.
A)True
B)False
47
NAD is derived from niacin, a water-soluble vitamin known as B3.
A)True
B)False
48
FAD can accept two electrons and become FADH2, but NAD can only accept one electron and become NADH.
A)True
B)False
49
Since the vitamin riboflavin (vitamin B2) is converted to a coenzyme that transfers electrons in the energy-producing reactions, eating riboflavin supplements provides extra energy.
A)True
B)False
50
In a hypothetical reaction XH2 + Y → X + YH2, the compound X is a reducing agent.
A)True
B)False
51
In a hypothetical reaction XH2 + Y → X + YH2, the compound Y becomes oxidized.
A)True
B)False





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