BIOL 271 Module 2 | Microbiology w/Lab Exam Q&A |
Portage Learning
1. Which term describes the sum of all chemical reactions within a living organism?
A) Catabolism
B) Anabolism
C) Metabolism
D) Homeostasis
Correct Answer: Metabolism
Rationale: Metabolism is the overarching term for all biochemical reactions in a cell,
encompassing both catabolism (breakdown) and anabolism (synthesis). It is a
controlled set of reactions that occur in all living organisms to maintain life.
Catabolism and anabolism are the two subdivisions of metabolism.
2. The breakdown of complex organic molecules into simpler compounds, releasing
energy, is known as:
A) Anabolism
B) Catabolism
C) Biosynthesis
D) Photosynthesis
Correct Answer: Catabolism
Rationale: Catabolism is the exergonic process of breaking down larger molecules
into smaller ones, releasing energy that is captured in the form of ATP. This energy is
then used to drive anabolic reactions. Photosynthesis is a process used by
phototrophs to capture light energy.
3. The building of complex molecules from simpler ones, requiring energy input, is
known as:
,A) Catabolism
B) Metabolism
C) Anabolism
D) Fermentation
Correct Answer: Anabolism
Rationale: Anabolism is the endergonic process of synthesizing complex cellular
components from simpler precursors, requiring the energy derived from catabolic
reactions. This process is essential for cell growth, repair, and reproduction.
4. What is the primary function of an enzyme in a metabolic reaction?
A) To increase the activation energy of the reaction
B) To decrease the activation energy of the reaction
C) To provide energy for the reaction
D) To change the equilibrium of the reaction
Correct Answer: To decrease the activation energy of the reaction
Rationale: Enzymes are biological catalysts that speed up chemical reactions by
lowering the activation energy barrier. This allows metabolic processes to occur
rapidly at temperatures compatible with life. Enzymes are not consumed in the
reaction and do not alter the reaction's equilibrium.
5. True or False: Enzymes are consumed during the chemical reactions they
catalyze.
A) True
B) False
Correct Answer: False
,Rationale: Enzymes are not consumed during the reactions they catalyze; they can
be reused repeatedly. They function by lowering the activation energy and facilitating
the conversion of substrates to products, after which they are regenerated to
catalyze another reaction.
6. A non-protein molecule that assists an enzyme in catalyzing a reaction is called a:
A) Substrate
B) Cofactor
C) Inhibitor
D) Holoenzyme
Correct Answer: Cofactor
Rationale: A cofactor is a non-protein chemical compound that is required for the
biological activity of an enzyme. Cofactors can be inorganic ions (e.g., metal ions like
Mg²⁺, Zn²⁺) or organic molecules known as coenzymes. Without its cofactor, an
enzyme may be inactive.
7. The specific molecule upon which an enzyme acts is called the:
A) Cofactor
B) Product
C) Inhibitor
D) Substrate
Correct Answer: Substrate
Rationale: The substrate is the molecule that an enzyme binds to and acts upon.
The enzyme's active site has a specific shape that binds to its substrate, forming an
enzyme-substrate complex. This specificity is key to the enzyme's function.
8. The region on an enzyme where the substrate binds is called the:
A) Allosteric site
, B) Active site
C) Binding pocket
D) Regulatory site
Correct Answer: Active site
Rationale: The active site is a specific region on the enzyme where the substrate
binds. It has a unique three-dimensional shape that is complementary to the
substrate, allowing for specific binding and catalysis. The active site is where the
chemical reaction takes place.
9. Which factor can cause an enzyme to become denatured and lose its function?
A) Low temperature
B) Optimal pH
C) High temperature
D) Presence of a cofactor
Correct Answer: High temperature
Rationale: High temperatures can disrupt the weak bonds (hydrogen bonds, ionic
interactions) that maintain the enzyme's specific three-dimensional structure, leading
to denaturation. This alters the active site's shape and renders the enzyme non-
functional. Cold typically slows but does not denature enzymes.
10. A microorganism that uses light as its energy source and carbon dioxide as its
carbon source is classified as a:
A) Chemoheterotroph
B) Photoheterotroph
C) Chemoautotroph
D) Photoautotroph
Correct Answer: Photoautotroph
Portage Learning
1. Which term describes the sum of all chemical reactions within a living organism?
A) Catabolism
B) Anabolism
C) Metabolism
D) Homeostasis
Correct Answer: Metabolism
Rationale: Metabolism is the overarching term for all biochemical reactions in a cell,
encompassing both catabolism (breakdown) and anabolism (synthesis). It is a
controlled set of reactions that occur in all living organisms to maintain life.
Catabolism and anabolism are the two subdivisions of metabolism.
2. The breakdown of complex organic molecules into simpler compounds, releasing
energy, is known as:
A) Anabolism
B) Catabolism
C) Biosynthesis
D) Photosynthesis
Correct Answer: Catabolism
Rationale: Catabolism is the exergonic process of breaking down larger molecules
into smaller ones, releasing energy that is captured in the form of ATP. This energy is
then used to drive anabolic reactions. Photosynthesis is a process used by
phototrophs to capture light energy.
3. The building of complex molecules from simpler ones, requiring energy input, is
known as:
,A) Catabolism
B) Metabolism
C) Anabolism
D) Fermentation
Correct Answer: Anabolism
Rationale: Anabolism is the endergonic process of synthesizing complex cellular
components from simpler precursors, requiring the energy derived from catabolic
reactions. This process is essential for cell growth, repair, and reproduction.
4. What is the primary function of an enzyme in a metabolic reaction?
A) To increase the activation energy of the reaction
B) To decrease the activation energy of the reaction
C) To provide energy for the reaction
D) To change the equilibrium of the reaction
Correct Answer: To decrease the activation energy of the reaction
Rationale: Enzymes are biological catalysts that speed up chemical reactions by
lowering the activation energy barrier. This allows metabolic processes to occur
rapidly at temperatures compatible with life. Enzymes are not consumed in the
reaction and do not alter the reaction's equilibrium.
5. True or False: Enzymes are consumed during the chemical reactions they
catalyze.
A) True
B) False
Correct Answer: False
,Rationale: Enzymes are not consumed during the reactions they catalyze; they can
be reused repeatedly. They function by lowering the activation energy and facilitating
the conversion of substrates to products, after which they are regenerated to
catalyze another reaction.
6. A non-protein molecule that assists an enzyme in catalyzing a reaction is called a:
A) Substrate
B) Cofactor
C) Inhibitor
D) Holoenzyme
Correct Answer: Cofactor
Rationale: A cofactor is a non-protein chemical compound that is required for the
biological activity of an enzyme. Cofactors can be inorganic ions (e.g., metal ions like
Mg²⁺, Zn²⁺) or organic molecules known as coenzymes. Without its cofactor, an
enzyme may be inactive.
7. The specific molecule upon which an enzyme acts is called the:
A) Cofactor
B) Product
C) Inhibitor
D) Substrate
Correct Answer: Substrate
Rationale: The substrate is the molecule that an enzyme binds to and acts upon.
The enzyme's active site has a specific shape that binds to its substrate, forming an
enzyme-substrate complex. This specificity is key to the enzyme's function.
8. The region on an enzyme where the substrate binds is called the:
A) Allosteric site
, B) Active site
C) Binding pocket
D) Regulatory site
Correct Answer: Active site
Rationale: The active site is a specific region on the enzyme where the substrate
binds. It has a unique three-dimensional shape that is complementary to the
substrate, allowing for specific binding and catalysis. The active site is where the
chemical reaction takes place.
9. Which factor can cause an enzyme to become denatured and lose its function?
A) Low temperature
B) Optimal pH
C) High temperature
D) Presence of a cofactor
Correct Answer: High temperature
Rationale: High temperatures can disrupt the weak bonds (hydrogen bonds, ionic
interactions) that maintain the enzyme's specific three-dimensional structure, leading
to denaturation. This alters the active site's shape and renders the enzyme non-
functional. Cold typically slows but does not denature enzymes.
10. A microorganism that uses light as its energy source and carbon dioxide as its
carbon source is classified as a:
A) Chemoheterotroph
B) Photoheterotroph
C) Chemoautotroph
D) Photoautotroph
Correct Answer: Photoautotroph
