Tiye Strong
1) Which of the following compounds is NOT an enzyme?
A) dehydrogenase
B) cellulase
C) coenzyme A
D) β-galactosidase
E) sucrase
2) Figure 5.1
Which compound is being reduced in the reaction shown in Figure 5.1?
A) isocitric acid and α-ketoglutaric acid
B) α-ketoglutaric acid and NAD+
C) NAD+
D) NADH
E) NADH and isocitric acid
3) Which organism is NOT correctly matched to its energy source?
A) photoheterotroph - light
B) photoautotroph - CO2
C) chemoautotroph - Fe2+
D) chemoheterotroph - glucose
E) chemoautotroph-NH3
4) Which of the following statements about anaerobic respiration is FALSE?
A) It yields lower amounts of ATP when compared to aerobic respiration.
B) The complete Kreb's cycle is utilized.
C) It involves the reduction of an organic final electron acceptor.
D) It generates ATP.
E) It requires cytochromes.
5) Figure 5.2
What type of reaction is in Figure 5.2?
A) decarboxylation
B) transamination
C) dehydrogenation
D) oxidation
E) reduction
6) What is the fate of pyruvic acid in an organism that uses aerobic respiration?
A) It is reduced to lactic acid.
B) It reacts with oxaloacetate to form citrate.
C) It is oxidized in the electron transport chain.
D) It is catabolized in glycolysis.
E) It is converted into acetyl CoA.
7) Figure 5.3
How would a noncompetitive inhibitor interfere with a reaction involving the enzyme shown in
Figure 5.3?
A) It would bind to a.
B) It would bind to b.
C) It would bind to c.
D) It would bind to d.
E) The answer cannot be determined based on the information provided.
8) Figure 5.4
How is ATP generated in the reaction shown in Figure 5.4?
A) glycolysis
B) fermentation
C) photophosphorylation
D) oxidative phosphorylation
E) substrate-level phosphorylation
9) Fatty acids are oxidized in
A) the Krebs cycle.
B) the electron transport chain.
C) glycolysis.
D) the pentose phosphate pathway.
E) the Entner-Doudoroff pathway.
10) Figure 5.5
Which of the graphs in Figure 5.5 best illustrates the activity of an enzyme that is saturated with
substrate?
A) a
B) b
C) c
D) d
E) e
11) Which of the following is the best definition of oxidative phosphorylation?
A) Electrons are passed through a series of carriers to O2.
B) A proton gradient allows hydrogen ions to flow back into the cells through transmembrane
protein channels, releasing energy that is used to generate ATP.
C) ATP is directly transferred from a substrate to ADP.
D) Electrons are passed through a series of carriers to an organic compound.
12) Which of the following statements about substrate-level phosphorylation is FALSE?
A) It involves the direct transfer of a high-energy phosphate group from an intermediate
metabolic compound to ADP.
B) No final electron acceptor is required.
C) It occurs in glycolysis.
D) The oxidation of intermediate metabolic compounds releases energy that is used to generate
ATP.
E) It occurs to a lesser degree in the Krebs cycle than in glycolysis.
13) Which of the following statements about photophosphorylation is FALSE?
A) Light liberates an electron from chlorophyll.
B) The oxidation of carrier molecules releases energy.
C) Energy from oxidation reactions is used to generate ATP from ADP.
D) It requires CO2.
E) It occurs in photosynthesizing cells.
14) A strictly fermentative bacterium produces energy
A) by glycolysis only.
B) by aerobic respiration only.
C) by fermentation or aerobic respiration.
D) only in the absence of oxygen.
E) only in the presence of oxygen.
15) Which of the following statements regarding metabolism is FALSE?
A) Heat may be released in both anabolic and catabolic reactions.
B) ATP is formed in catabolic reactions.
C) ADP is formed in anabolic reactions.
D) Anabolic reactions are degradative.
16) Which of the following is TRUE about this reaction?
NO3-+ 2H+
Nitrate ion
NO2- + H2O
Nitrite ion
A) This process requires O2.
B) This process occurs anaerobically.
C) This process requires the entire electron transport system.
D) This process requires light.
E) This process requires O2 and the electron transport system.
17) Which of the following statements regarding the Entner-Doudoroff pathway is TRUE?
A) It involves glycolysis.
B) It involves the pentose phosphate pathway.
C) NADH is generated.
D) ATP is generated.
E) NADH and ATP are generated.
19) Assume you are working for a chemical company and are responsible for growing a yeast
culture that produces ethanol. The yeasts are growing well on the maltose medium but are not
producing alcohol. What is the most likely explanation?
A) The maltose is toxic.
B) O2 is in the medium.
C) Not enough protein is provided.
D) The temperature is too low.
E) The temperature is too high.
20) Figure 5.6
The rates of O2 and glucose consumption by a bacterial culture are shown in Figure 5.6. Assume
a bacterial culture was grown in a glucose medium without O2. Then O2 was added at the time
marked X. The data indicate that
A) these bacteria don't use O2.
B) these bacteria get more energy anaerobically.
C) aerobic metabolism is more efficient than fermentation.
D) these bacteria cannot grow anaerobically.
21) An enzyme, citrate synthase, in the Krebs cycle is inhibited by ATP. This is an example of
all of the following EXCEPT
A) allosteric inhibition.
B) competitive inhibition.
C) feedback inhibition.
D) noncompetitive inhibition.
22) If a cell is starved for ATP, which of the following pathways would most likely be shut
down?
A) Kreb's cycle
B) glycolysis
C) pentose phosphate pathway
D) Krebs cycle and glycolysis
23) Which of the following statements regarding the glycolysis pathway is FALSE?
A) Two pyruvate molecules are generated.
B) Four ATP molecules are generated via substrate-level phosphorylation.
C) Two NADH molecules are generated.
D) One molecule of ATP is expended.
E) Two molecules of water are generated.
24) Figure 5.7
The graph at the left in Figure 5.7 shows the reaction rate for an enzyme at its optimum
temperature. Which graph shows enzyme activity at a higher temperature?
A) a
B) b
C) c
D) d
25) A bacterial culture grown in a glucose-peptide medium causes the pH to increase. The
bacteria are most likely
A) fermenting the glucose.
B) oxidizing the glucose.
C) using the peptides.
D) not growing.
26) Gallionella bacteria can get energy from the reaction Fe2+ → Fe3+. This reaction is an
example of
A) oxidation.
B) reduction.
C) fermentation.
D) photophosphorylation.
E) the Calvin-Benson cycle.
Figure 5.8
27) In Figure 5.8, where is ATP produced?
A) a
B) b
C) c
D) d
E) e
28) Refer to Figure 5.8. In aerobic respiration, where is water formed?
A) a
B) b
C) c
D) d
E) e
29) In Figure 5.8, the structure labeled "1" is
A) NAD+.
B) ATP synthase.
C) a plasma membrane.
D) a cell wall.
E) cytoplasm.
30) In Figure 5.8, the path labeled "2" is the flow of
A) electrons.
B) protons.
C) energy.
D) water.
E) glucose.
32) What is the most acidic place in Figure 5.8?
A) a
B) b
C) c
D) d
E) e
33) A urease test is used to identify Mycobacterium tuberculosis because
A) urease is a sign of tuberculosis.
B) M. tuberculosis produces urease.
C) urea accumulates during tuberculosis.
D) some bacteria reduce nitrate ion.
E) M. bovis can cause tuberculosis.
Discussion Questions:
1. Explain how ATP stores chemical energy and makes it available to a cell.
the second and third phosphates of ATP are attached by high-energy bonds, and the chemical
energy stored in one of the bonds may be quickly transferred to another molecule in a metabolic
reaction.
2. Explain how the reactions of cellular respiration release chemical energy.
cellular respiration releases energy through 3 distinct, interconnected reactions. Glycolysis, the
citric acid cycle, and the electron transport chain
3. Describe how DNA molecules store genetic information.
DNA stores information in a sequence of adenine, cytosine, guanine and thymine on a backbone
of two deoxyribose molecules, which intertwine in a double helix.
4. Explain how protein synthesis relies on genetic information.
DNA molecules are in the nucleus and protein synthesis occurs in the cytoplasm. Because the
cell must keep a permanent copy of the genetic instructions, genetic information must get from
the nucleus into the cytoplasm for the cell to use it.
5. Compare and contrast DNA and RNA.
RNA-single stranded, nucleotides have ribose rather than deoxyribose sugar. DNA+RNA have
one of four nitrogenous bases, but whereas adenine, cytosine, and guanine nucleotides are part of
DNA+RNA. Thymine is only in DNA. RNA molecules have uracil nucleotides.
6. Explain how a mutation may or may not affect an organism.
mutations can affect an organism by altering its phenotype. or it can alter an organism's
genotype.
7. Describe how DNA molecules are replicated.
when the two complementary DNA strands are separated. This is usually accomplished by
special proteins that unwind the molecule and expose the nucleotide bases
8. Identify the components of an enzyme.
A large protein enzyme molecule is composed of one or more amino acid chains called
polypeptide chains. The amino acid sequence determines the characteristic folding patterns of the
protein's structure, which is essential to enzyme specificity.
9. Describe the mechanism of enzymatic action.
Step 1 of mechanisms of enzymatic action
surface of the substrate contacts a specific region on the surface of the enzyme called the active
site
step 2 of mechanisms of enzymatic action
a temporary enzyme-substrate complex forms lock and key
step 3 of mechanisms of enzymatic action
substrate is transformed to products
step 4 of mechanisms of enzymatic action
enzyme and products separate
step 5 of mechanisms of enzymatic action
unchanged enzyme can react with other substrate
10. Distinguish competitive and noncompetitive inhibition.
-COMPETITIVE inhibition= inhibitor & substrate both bind to the active site of the enzyme.
binding of an inhibitor prevents substrate binding, thereby inhibiting enzyme activity.
-NONCOMPETITIVE inhibition= inhibitor & substrate bind to different sites. binding of an
inhibitor distorts the enzyme, inhibiting substrate binding or reducing catalytic activity.
11. Define ribozyme.
Ribozymes are catalytically active RNA molecules or RNA–protein complexes, in which solely
the RNA provides catalytic activity. The term ribozyme refers to the enzymatic activity and
ribonucleic acid nature at the same time.
12. Define fermentation in prokaryotic organisms such as yeast.