BIO 201 MIDTERM EXAM – A&P
REVIEW QUESTIONS WITH CORRECT
ANSWERS
1. Which of the following best describes the relationship between a negative feedback loop
and homeostasis?
A. Negative feedback loops shift the body away from its set point to achieve a new
equilibrium.
B. Negative feedback loops amplify the stimulus to reach a rapid physiological peak.
C. Negative feedback loops counteract a stimulus to return the body to its set point.
D. Negative feedback loops only occur during extreme physiological stress or illness.
Answer: C
Conceptual Explanation: Homeostasis is primarily maintained through negative feedback
loops, where the output of the system shuts off the original stimulus or reduces its intensity
to return the body to a stable set point.
,2. A substance that releases hydroxyl ions (OH-) in water and has a pH of 12 would be
classified as a:
A. Strong acid
B. Neutral buffer
C. Weak acid
D. Strong base
Answer: D
Conceptual Explanation: Bases release OH- ions in solution. A pH of 12 is significantly
higher than the neutral pH of 7, indicating a strong base.
3. In a molecule of water, the oxygen atom is more electronegative than the hydrogen atoms.
This results in what type of bond between the atoms?
A. Polar covalent bond
B. Ionic bond
C. Nonpolar covalent bond
D. Hydrogen bond
Answer: A
Conceptual Explanation: Polar covalent bonds occur when electrons are shared unequally
between atoms due to differences in electronegativity, creating partial charges.
, 4. Which level of protein structure is characterized by the alpha-helix or beta-pleated sheet
formed by hydrogen bonding?
A. Primary structure
B. Secondary structure
C. Tertiary structure
D. Quaternary structure
Answer: B
Conceptual Explanation: Secondary structure refers to local folding patterns like alpha-
helices and beta-sheets held together by hydrogen bonds between the peptide backbone.
5. Enzymes act as biological catalysts by:
A. Increasing the activation energy required for a reaction
B. Increasing the temperature of the reactants
C. Changing the final equilibrium of the reaction
D. Lowering the activation energy required for a reaction
Answer: D
Conceptual Explanation: Enzymes lower the activation energy barrier, allowing chemical
reactions to proceed faster at body temperature.
REVIEW QUESTIONS WITH CORRECT
ANSWERS
1. Which of the following best describes the relationship between a negative feedback loop
and homeostasis?
A. Negative feedback loops shift the body away from its set point to achieve a new
equilibrium.
B. Negative feedback loops amplify the stimulus to reach a rapid physiological peak.
C. Negative feedback loops counteract a stimulus to return the body to its set point.
D. Negative feedback loops only occur during extreme physiological stress or illness.
Answer: C
Conceptual Explanation: Homeostasis is primarily maintained through negative feedback
loops, where the output of the system shuts off the original stimulus or reduces its intensity
to return the body to a stable set point.
,2. A substance that releases hydroxyl ions (OH-) in water and has a pH of 12 would be
classified as a:
A. Strong acid
B. Neutral buffer
C. Weak acid
D. Strong base
Answer: D
Conceptual Explanation: Bases release OH- ions in solution. A pH of 12 is significantly
higher than the neutral pH of 7, indicating a strong base.
3. In a molecule of water, the oxygen atom is more electronegative than the hydrogen atoms.
This results in what type of bond between the atoms?
A. Polar covalent bond
B. Ionic bond
C. Nonpolar covalent bond
D. Hydrogen bond
Answer: A
Conceptual Explanation: Polar covalent bonds occur when electrons are shared unequally
between atoms due to differences in electronegativity, creating partial charges.
, 4. Which level of protein structure is characterized by the alpha-helix or beta-pleated sheet
formed by hydrogen bonding?
A. Primary structure
B. Secondary structure
C. Tertiary structure
D. Quaternary structure
Answer: B
Conceptual Explanation: Secondary structure refers to local folding patterns like alpha-
helices and beta-sheets held together by hydrogen bonds between the peptide backbone.
5. Enzymes act as biological catalysts by:
A. Increasing the activation energy required for a reaction
B. Increasing the temperature of the reactants
C. Changing the final equilibrium of the reaction
D. Lowering the activation energy required for a reaction
Answer: D
Conceptual Explanation: Enzymes lower the activation energy barrier, allowing chemical
reactions to proceed faster at body temperature.
