Chapter 5 Microbiology
Which of the following molecules is broken down in cellular respiration, providing fuel for the cell?
Glucose There is a ball-and-stick model of a molecule of glucose.
Which of the following statements about glycolysis is true?
Glycolysis is also called the Embden-Meyerhof pathway.
In noncyclic photophosphorylation, O2 is released from
H2O
In green and purple bacteria, electrons to reduce CO2 can come from
H2S
Which of the following statements are TRUE? 1-Electron carriers are located at ribosomes. 2-ATP is a common intermediate between catabolic and anabolic pathways. 3-ATP is used for the long-term storage of energy and so is often found in storage granules. 4-Anaerobic organisms are capable of generating ATP via respiration. 5-ATP can be generated by the flow of protons across protein channels.
2,4,5
Which of the following is the best definition of oxidative phosphorylation?
A proton gradient allows hydrogen ions to flow back into the cells through transmembrane protein channels, releasing energy that is used to generate ATP.
Which energy-rich molecule directly powers cell work?
ATP The figure represents an ATP molecule.
Why is ATP required for glycolysis?
ATP makes it easier to break apart glucose into two three-carbon molecules.
What is the intermediate product formed by pyruvic acid during alcoholic fermentation?
Acetaldehyde
Which of the following is true of aerobic respiration compared to anaerobic respiration?
Aerobic respiration uses oxygen as a final electron acceptor, whereas anaerobic respiration uses an inorganic molecule other than oxygen as the final electron acceptor.
Where would you expect to find electron transport chains in a prokaryote?
Along the plasma membrane
What is the function of GTP?
An energy carrier
Which of the following matches enzyme components with their correct definition and/or function?
Coenzymes are the organic cofactors important to enzyme activity.
Which of the following statements regarding competitive inhibitors is true?
Competitive inhibitors decrease the rate of enzyme activity.
What enables competitive inhibitors to bind to a specific enzyme?
Competitive inhibitors have structures that resemble the enzyme's substrate.
What occurs at the bridge step?
Decarboxylation of pyruvic acid
Why are enzymes important to biological systems?
Enzymes decrease the amount of activation energy required for chemical reactions to occur.
What is meant by the statement "Enzymes are biological catalysts"?
Enzymes speed up the chemical reactions in living cells.
Based on the animation, how many electron carriers are reduced in the Krebs cycle only?
Four
How is nevirapine used to treat HIV infections?
It alters the active site of reverse transcriptase, decreasing that enzyme's activity.
Which of the following statements about fermentation is true?
It is an alternative way to return electron carriers to their oxidized state.
What is the fate of the NAD+ newly regenerated by fermentation?
It returns to glycolysis to pick up more electrons.
What is the role of pyruvic acid in fermentation?
It takes the electrons from NADH, oxidizing it back into NAD+.
Which of the following is an acid produced by fermentation?
Lactic acid and propionic acid
Which of the following statements is FALSE regarding the oxidation of proteins?
Microbes produce extracellular enzymes to reduce proteins to their fatty acid and glycerol components so that each component can enter the Krebs cycle.
According to the animation, which compounds provide electrons to the system?
NADH and FADH2
What would be the likely outcome if you increased the concentration of substrate for an enzyme in the presence of a noncompetitive inhibitor?
No change in enzyme activity would be observed.
What carbon molecules remain at the end of glycolysis?
Pyruvic acid
Which of the following statements regarding redox reactions is true?
Redox reactions involve an oxidation reaction coupled with a reduction reaction.
Which of the following is true concerning ribozymes?
Ribozymes have an active site and are not used up in chemical reactions.
According to the animation, what does the electron transport chain do to the concentration of hydrogen ions (protons)?
The concentration of protons is higher outside the membrane than inside.
Why is reduction the term used to describe the gain of an electron?
The electron acceptor's net charge decreases.
If high amounts of sulfanilamide are in the presence of an enzyme whose substrate is PABA, what outcome is expected?
The enzyme will stop functioning.
How does a noncompetitive inhibitor reduce an enzyme's activity?
The inhibitor binds to the enzyme in a location other than the active site, changing the shape of the active site.
What is the fate of metabolites during respiration?
They are oxidized completely to carbon dioxide and water.
How does a competitive inhibitor slow enzyme catalysis?
They compete with the substrate for the enzyme's active site.
Both respiration and photosynthesis require the use of an electron transport chain.
True
Once an enzyme has converted substrates into products, the active site reverts back to its original form.
True
How many net ATPs can be made from one molecule of glucose in glycolysis?
Two
According to the animation, what does oxygen get reduced to at the end of the electron transport chain?
Water
What is the most acidic place in the figure?
a
In the figure, the structure labeled "1" is
a plasma membrane
A reaction that involves the transfer of electrons from one molecule to another is referred to as
a redox reaction.
A strictly fermentative bacterium produces energy
by glycolysis only
The process of generating ATP using a proton gradient is referred to as
chemiosmosis
Which of the following uses CO2 for carbon and H2 for energy?
chemoautotroph
Which of the following uses glucose for carbon and energy?
chemoheterotroph
Refer to the figure. In aerobic respiration, where is water formed?
d
In the figure, where is ATP produced?
e
Why do all enzymatic reactions need activation energy?
energy is required to disrupt a substrate's stable electron configuration
Cyanobacteria are a type of
photoautotroph
Which of the following has bacteriochlorophylls and uses alcohols for carbon?
photoheterotroph
In the figure, the path labeled "2" is the flow of
protons
Which of the following actions would increase enzymatic activity in a bacterial cell that normally thrives in the human body?
slightly increasing the temperature within the optimum range
Much of the energy released in catabolic reactions is captured in ATP for use in other reactions. When the phosphate is transferred directly from an organic molecule to ADP in order to produce ATP without an energized membrane, what has occurred?
substrate-level phosphorylation
Glycolysis literally means
sugar splitting.
Fatty acids are oxidized in
the Krebs cycle
During an oxidation reaction,
the donor molecule loses an electron and becomes oxidized.
Which of the following is the best definition of fermentation?
the partial oxidation of glucose with organic molecules serving as electron acceptors
