BIOL 101 Quiz 2 V3 | BIOL 101 Principles of
Biology | Actual Q&A with Rationale (BIOL101 Quiz
2) | Liberty University
1. Which of the following statements best describes the Second Law of Thermodynamics in a
biological context?
A. Energy cannot be created or destroyed, only transformed.
B. Biological systems are exempt from the laws of physics due to their complexity.
C. Evolution leads to a decrease in the total entropy of the universe over time.
D. Every energy transfer or transformation increases the entropy of the universe.
Correct Answer: D
Explanation: The Second Law of Thermodynamics dictates that spontaneous processes,
those that occur without energy input, must increase the entropy of the universe. While
organisms may become more organized, they achieve this by releasing heat and metabolic
waste, thereby increasing the surrounding disorder. This principle is fundamental to
understanding how energy flow dictates biological processes.
2. During cellular respiration, what is the primary role of NAD+?
A. It functions as an oxidizing agent, accepting electrons to become NADH.
B. It acts as a final electron acceptor at the end of the electron transport chain.
C. It provides the energy required for the phosphorylation of ADP to ATP.
,D. It catalyzes the breakdown of glucose during the initial steps of glycolysis.
Correct Answer: A
Explanation: NAD+ serves as a critical coenzyme that functions as an electron carrier in
metabolic pathways. By accepting two electrons and one proton, it is reduced to NADH,
effectively storing potential energy. This energy is subsequently harvested during oxidative
phosphorylation to generate ATP.
3. In the fluid mosaic model of the plasma membrane, what is the main function of
cholesterol?
A. Facilitating the transport of ions across the hydrophobic bilayer.
B. Acting as a primary energy source for membrane-bound proteins.
C. Modulating membrane fluidity at varying temperatures.
D. Serving as a receptor for steroid hormones like testosterone.
Correct Answer: C
Explanation: Cholesterol is interspersed within the phospholipid bilayer to maintain
structural integrity. At high temperatures, it restricts the movement of phospholipids to
prevent the membrane from becoming too fluid. Conversely, at low temperatures, it
prevents tight packing, ensuring the membrane remains functional and fluid.
4. A cell is placed in a solution, and it begins to swell and eventually bursts. The solution is
____ to the cell.
A. Hypotonic
, B. Isotonic
C. Hypertonic
D. Equilibrium
Correct Answer: A
Explanation: A hypotonic solution has a lower solute concentration compared to the
interior of the cell. This concentration gradient causes water to move into the cell via
osmosis. In animal cells, which lack a rigid cell wall, this influx of water leads to lyse or
bursting.
5. Enzymes catalyze biological reactions by doing which of the following?
A. Increasing the total amount of free energy released by the reaction.
B. Lowering the activation energy barrier of the reaction.
C. Providing the thermal energy necessary for the reaction to proceed.
D. Changing the equilibrium constant to favor product formation.
Correct Answer: B
Explanation: Enzymes are biological catalysts that speed up chemical reactions without
being consumed. They achieve this by lowering the activation energy (Ea), which is the
energy required to reach the transition state. This allows metabolic processes to occur
rapidly at the temperatures compatible with life.
Biology | Actual Q&A with Rationale (BIOL101 Quiz
2) | Liberty University
1. Which of the following statements best describes the Second Law of Thermodynamics in a
biological context?
A. Energy cannot be created or destroyed, only transformed.
B. Biological systems are exempt from the laws of physics due to their complexity.
C. Evolution leads to a decrease in the total entropy of the universe over time.
D. Every energy transfer or transformation increases the entropy of the universe.
Correct Answer: D
Explanation: The Second Law of Thermodynamics dictates that spontaneous processes,
those that occur without energy input, must increase the entropy of the universe. While
organisms may become more organized, they achieve this by releasing heat and metabolic
waste, thereby increasing the surrounding disorder. This principle is fundamental to
understanding how energy flow dictates biological processes.
2. During cellular respiration, what is the primary role of NAD+?
A. It functions as an oxidizing agent, accepting electrons to become NADH.
B. It acts as a final electron acceptor at the end of the electron transport chain.
C. It provides the energy required for the phosphorylation of ADP to ATP.
,D. It catalyzes the breakdown of glucose during the initial steps of glycolysis.
Correct Answer: A
Explanation: NAD+ serves as a critical coenzyme that functions as an electron carrier in
metabolic pathways. By accepting two electrons and one proton, it is reduced to NADH,
effectively storing potential energy. This energy is subsequently harvested during oxidative
phosphorylation to generate ATP.
3. In the fluid mosaic model of the plasma membrane, what is the main function of
cholesterol?
A. Facilitating the transport of ions across the hydrophobic bilayer.
B. Acting as a primary energy source for membrane-bound proteins.
C. Modulating membrane fluidity at varying temperatures.
D. Serving as a receptor for steroid hormones like testosterone.
Correct Answer: C
Explanation: Cholesterol is interspersed within the phospholipid bilayer to maintain
structural integrity. At high temperatures, it restricts the movement of phospholipids to
prevent the membrane from becoming too fluid. Conversely, at low temperatures, it
prevents tight packing, ensuring the membrane remains functional and fluid.
4. A cell is placed in a solution, and it begins to swell and eventually bursts. The solution is
____ to the cell.
A. Hypotonic
, B. Isotonic
C. Hypertonic
D. Equilibrium
Correct Answer: A
Explanation: A hypotonic solution has a lower solute concentration compared to the
interior of the cell. This concentration gradient causes water to move into the cell via
osmosis. In animal cells, which lack a rigid cell wall, this influx of water leads to lyse or
bursting.
5. Enzymes catalyze biological reactions by doing which of the following?
A. Increasing the total amount of free energy released by the reaction.
B. Lowering the activation energy barrier of the reaction.
C. Providing the thermal energy necessary for the reaction to proceed.
D. Changing the equilibrium constant to favor product formation.
Correct Answer: B
Explanation: Enzymes are biological catalysts that speed up chemical reactions without
being consumed. They achieve this by lowering the activation energy (Ea), which is the
energy required to reach the transition state. This allows metabolic processes to occur
rapidly at the temperatures compatible with life.
