Energy And Enzymes Practice Questions Flashcards
Which of the following is an example of potential energy?
o A) Waterfall
o B) ATP stored in a cell
o C) Diffusion across a membrane
o D) Muscle contraction
Answer: B) ATP stored in a cell
What does the first law of thermodynamics state?
o A) Energy is created and destroyed.
o B) Energy cannot be created or destroyed, only transformed.
o C) Energy and matter always increase disorder.
o D) Energy is lost as heat in every reaction.
Answer: B) Energy cannot be created or destroyed, only transformed.
What is the primary molecule used by cells for energy?
o A) Glucose
o B) ATP
o C) DNA
o D) Lipids
Answer: B) ATP
Which one of the below processes is exergonic?
o A) Protein synthesis
o B) DNA replication
o C) Cellular respiration
o D) Active transport
Answer: C) Cellular respiration
What does “ΔG” represent?
o A) Change in entropy
o B) Change in free energy
o C) Change in potential energy
o D) Change in reaction speed
Answer: B) Change in free energy
Which of the following is true of enzymes?
o A) They are consumed during the reaction.
o B) They increase the activation energy of a reaction.
o C) They lower the activation energy of a reaction.
o D) They slow down chemical reactions.
Answer: C) They lower the activation energy of a reaction.
What happens to enzyme activity at extremely high temperatures?
o A) It increases indefinitely.
o B) It remains stable.
o C) The enzyme denatures.
o D) The substrate denatures.
Answer: C) The enzyme denatures
In competitive inhibition, the inhibitor binds to the:
A) Active site
B) Allosteric site
C) Substrate
D) Transition state
Answer: A) Active site
An example of a system moving toward higher entropy is:
o A) DNA replication
o B) A gas diffusing across a membrane
o C) Folding of a protein
o D) Formation of a solid crystal
Answer: B) A gas diffusing across a membrane
ATP hydrolysis is an example of:
o A) An endergonic reaction
o B) An exergonic reaction
o C) Competitive inhibition
o D) Non-competitive inhibition
Answer: B) An exergonic reaction
Which one of the following applies to a biological system?
o A) Closed system
o B) Open system
o C) Isolated system
o D) Static system
Answer: B) Open system
How does the induced-fit model differ from the lock-and-key model?
o A) It suggests enzymes are specific to one reaction only.
o B) It involves rigid active sites.
o C) It proposes the enzyme changes shape to fit the substrate.
o D) It requires non-competitive inhibition.
Answer: C) It proposes the enzyme changes shape to fit the substrate.
Which statement about Gibbs free energy (ΔG) is correct?
o A) ΔG > 0 indicates an exergonic reaction.
o B) ΔG < 0 indicates an exergonic reaction.
o C) ΔG = 0 means the system has lost all energy.
o D) ΔG is a measure of the change in heat during a reaction
Answer: B) ΔG < 0 indicates an exergonic reaction.
What is the main reason enzymes increase reaction rates?
o A) They raise the temperature of the reaction.
o B) They stabilize the transition state.
o C) They increase substrate concentration.
o D) They change the pH of the reaction.
Answer: B) They stabilize the transition state
What happens when a substrate reaches saturation with enzymes?
A) Reaction rate slows down.
B) Adding more substrate increases the rate.
C) Adding more enzyme increases the rate.
D) The substrate denatures.
Answer: C) Adding more enzyme increases the rate.
