UT Austin BIO 311C Exam 3 (pdf) | 2026/2027 | Introductory Biology I
Q&A | Biology
1. Which of the following best defines metabolism?
A) The breakdown of complex molecules into simpler ones
B) The synthesis of complex molecules from simpler ones
C) The totality of an organism's chemical reactions
D) The conversion of light energy to chemical energy
Correct Answer: The totality of an organism's chemical reactions
Rationale: Metabolism is the sum total of all chemical reactions that occur
within an organism. It includes both catabolic (breakdown) and anabolic
(synthesis) pathways.
2. A metabolic pathway that breaks down complex molecules to release
energy is known as a:
A) Anabolic pathway
B) Catabolic pathway
C) Synthetic pathway
D) Biosynthetic pathway
Correct Answer: Catabolic pathway
Rationale: Catabolic pathways are degradative processes that break down
complex molecules into simpler ones, releasing energy in the process. An
example of a catabolic reaction is lactate fermentation.
3. A metabolic pathway that consumes energy to build complex molecules is
known as a:
A) Catabolic pathway
B) Anabolic pathway
C) Degradative pathway
D) Exergonic pathway
,Correct Answer: Anabolic pathway
Rationale: Anabolic pathways are biosynthetic processes that consume
energy to build complex molecules from simpler ones. They are the opposite
of catabolic pathways.
4. The first law of thermodynamics states that:
A) Every energy transfer increases the entropy of the universe
B) Energy can be created and destroyed
C) Energy cannot be created or destroyed, only converted from one form to
another
D) Systems tend to become more disordered over time
Correct Answer: Energy cannot be created or destroyed, only converted from
one form to another
Rationale: The first law of thermodynamics, also known as the law of
conservation of energy, states that energy can be transformed but cannot be
created or destroyed.
5. The measure of disorder or randomness in a system is known as:
A) Energy
B) Enthalpy
C) Entropy
D) Free energy
Correct Answer: Entropy
Rationale: Entropy (S) is a measure of molecular disorder or randomness.
The second law of thermodynamics states that the entropy of the universe is
constantly increasing.
6. A reaction that releases energy and has a negative ΔG is called:
A) Endergonic
,B) Exergonic
C) Anabolic
D) Endothermic
Correct Answer: Exergonic
Rationale: An exergonic reaction proceeds with a net release of free energy
and has a negative ΔG. Such reactions are spontaneous and can be used to
do work, such as the breakdown of glucose during cellular respiration.
7. A reaction that absorbs energy and has a positive ΔG is called:
A) Exergonic
B) Endergonic
C) Catabolic
D) Exothermic
Correct Answer: Endergonic
Rationale: An endergonic reaction requires an input of energy and has a
positive ΔG. Such reactions are nonspontaneous and store free energy in the
products, such as photosynthesis.
8. The energy required to initiate a chemical reaction is called:
A) Activation energy
B) Free energy
C) Kinetic energy
D) Potential energy
Correct Answer: Activation energy
Rationale: Activation energy (Ea) is the initial energy required to start a
chemical reaction. This energy is needed to destabilize existing bonds and
allow new ones to form.
9. Enzymes speed up chemical reactions by:
, A) Increasing the activation energy
B) Decreasing the activation energy
C) Increasing the temperature
D) Consuming the reactants
Correct Answer: Decreasing the activation energy
Rationale: Enzymes are biological catalysts that lower the activation energy
barrier of a reaction, thereby increasing the rate of reaction without being
consumed in the process.
10. The specific region of an enzyme where the substrate binds is the:
A) Allosteric site
B) Active site
C) Binding site
D) Catalytic site
Correct Answer: Active site
Rationale: The active site is the region on the enzyme where the substrate
binds. It is typically a pocket or groove on the enzyme's surface with a
specific shape and chemical environment that complements the substrate.
11. A molecule that binds to the active site and blocks the substrate from
binding is a:
A) Non-competitive inhibitor
B) Allosteric regulator
C) Competitive inhibitor
D) Coenzyme
Correct Answer: Competitive inhibitor
Rationale: A competitive inhibitor directly competes with the substrate for
binding to the active site. Cyanide binding to cytochrome oxidase, where
oxygen would normally bind, is an example of competitive inhibition.
Q&A | Biology
1. Which of the following best defines metabolism?
A) The breakdown of complex molecules into simpler ones
B) The synthesis of complex molecules from simpler ones
C) The totality of an organism's chemical reactions
D) The conversion of light energy to chemical energy
Correct Answer: The totality of an organism's chemical reactions
Rationale: Metabolism is the sum total of all chemical reactions that occur
within an organism. It includes both catabolic (breakdown) and anabolic
(synthesis) pathways.
2. A metabolic pathway that breaks down complex molecules to release
energy is known as a:
A) Anabolic pathway
B) Catabolic pathway
C) Synthetic pathway
D) Biosynthetic pathway
Correct Answer: Catabolic pathway
Rationale: Catabolic pathways are degradative processes that break down
complex molecules into simpler ones, releasing energy in the process. An
example of a catabolic reaction is lactate fermentation.
3. A metabolic pathway that consumes energy to build complex molecules is
known as a:
A) Catabolic pathway
B) Anabolic pathway
C) Degradative pathway
D) Exergonic pathway
,Correct Answer: Anabolic pathway
Rationale: Anabolic pathways are biosynthetic processes that consume
energy to build complex molecules from simpler ones. They are the opposite
of catabolic pathways.
4. The first law of thermodynamics states that:
A) Every energy transfer increases the entropy of the universe
B) Energy can be created and destroyed
C) Energy cannot be created or destroyed, only converted from one form to
another
D) Systems tend to become more disordered over time
Correct Answer: Energy cannot be created or destroyed, only converted from
one form to another
Rationale: The first law of thermodynamics, also known as the law of
conservation of energy, states that energy can be transformed but cannot be
created or destroyed.
5. The measure of disorder or randomness in a system is known as:
A) Energy
B) Enthalpy
C) Entropy
D) Free energy
Correct Answer: Entropy
Rationale: Entropy (S) is a measure of molecular disorder or randomness.
The second law of thermodynamics states that the entropy of the universe is
constantly increasing.
6. A reaction that releases energy and has a negative ΔG is called:
A) Endergonic
,B) Exergonic
C) Anabolic
D) Endothermic
Correct Answer: Exergonic
Rationale: An exergonic reaction proceeds with a net release of free energy
and has a negative ΔG. Such reactions are spontaneous and can be used to
do work, such as the breakdown of glucose during cellular respiration.
7. A reaction that absorbs energy and has a positive ΔG is called:
A) Exergonic
B) Endergonic
C) Catabolic
D) Exothermic
Correct Answer: Endergonic
Rationale: An endergonic reaction requires an input of energy and has a
positive ΔG. Such reactions are nonspontaneous and store free energy in the
products, such as photosynthesis.
8. The energy required to initiate a chemical reaction is called:
A) Activation energy
B) Free energy
C) Kinetic energy
D) Potential energy
Correct Answer: Activation energy
Rationale: Activation energy (Ea) is the initial energy required to start a
chemical reaction. This energy is needed to destabilize existing bonds and
allow new ones to form.
9. Enzymes speed up chemical reactions by:
, A) Increasing the activation energy
B) Decreasing the activation energy
C) Increasing the temperature
D) Consuming the reactants
Correct Answer: Decreasing the activation energy
Rationale: Enzymes are biological catalysts that lower the activation energy
barrier of a reaction, thereby increasing the rate of reaction without being
consumed in the process.
10. The specific region of an enzyme where the substrate binds is the:
A) Allosteric site
B) Active site
C) Binding site
D) Catalytic site
Correct Answer: Active site
Rationale: The active site is the region on the enzyme where the substrate
binds. It is typically a pocket or groove on the enzyme's surface with a
specific shape and chemical environment that complements the substrate.
11. A molecule that binds to the active site and blocks the substrate from
binding is a:
A) Non-competitive inhibitor
B) Allosteric regulator
C) Competitive inhibitor
D) Coenzyme
Correct Answer: Competitive inhibitor
Rationale: A competitive inhibitor directly competes with the substrate for
binding to the active site. Cyanide binding to cytochrome oxidase, where
oxygen would normally bind, is an example of competitive inhibition.
