Free Factors Affecting Enzyme Action MCQs with Answers
40 Factors Affecting Enzyme Action MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Enzyme activity changes with temperature, pH, substrate concentration and enzyme concentration because these factors affect molecular collisions and the active site. Questions also examine optimum conditions, denaturation and inhibition, while distinguishing a fall in activity caused by unsuitable conditions from permanent enzyme damage.
Last updated
40 questions · page 1 of 2
- A. is used up by the reaction
- B. is denatured as its tertiary structure breaks down
- C. becomes a substrate itself
- D. loses its active site to the product
Explanation: Heat breaks the hydrogen bonds and other weak interactions holding the tertiary structure, so the active site loses its shape and can no…
Correct answer: is denatured as its tertiary structure breaks down- A. Salivary amylase
- B. Pepsin
- C. Trypsin
- D. Catalase
Explanation: Pepsin is secreted into the stomach where hydrochloric acid keeps the pH near 2, and its structure is stable and active in exactly those…
Correct answer: Pepsin- A. the substrate begins to inhibit the enzyme
- B. all the active sites are occupied and the enzyme is saturated
- C. the enzyme is denatured by the excess substrate
- D. the products are used up
Explanation: Once every active site is engaged, adding more substrate cannot raise the rate, because the enzyme is already working as fast as it can…
Correct answer: all the active sites are occupied and the enzyme is saturated- A. the enzyme molecules multiply
- B. the activation energy of the reaction falls further
- C. the active site changes shape to fit better
- D. molecules move faster, so enzyme and substrate collide more often and with more energy
Explanation: Heat increases kinetic energy, so there are more successful collisions between enzyme and substrate per second and more enzyme substrate…
Correct answer: molecules move faster, so enzyme and substrate collide more often and with more energy- A. 37 degrees Celsius
- B. 25 degrees Celsius
- C. 60 degrees Celsius
- D. 100 degrees Celsius
Explanation: Human enzymes have evolved to work fastest at normal body temperature, which is why homeostatic control of temperature matters so much.
Correct answer: 37 degrees Celsius- A. reduces the number of substrate molecules present
- B. alters the charges on the R groups, changing the shape of the active site
- C. lowers the temperature of the mixture
- D. converts the enzyme into a substrate
Explanation: Excess hydrogen or hydroxide ions interfere with the ionic and hydrogen bonds between the side chains that hold the tertiary structure, so…
Correct answer: alters the charges on the R groups, changing the shape of the active site- A. reaches Vmax only at very high substrate concentrations
- B. has been irreversibly inhibited
- C. has a high affinity for that substrate, reaching half its maximum rate at a low concentration
- D. is working below its optimum temperature
Explanation: Km is the substrate concentration at which the reaction runs at half of Vmax, so a small Km means the active sites are half occupied even…
Correct answer: has a high affinity for that substrate, reaching half its maximum rate at a low concentration- A. independent of enzyme concentration
- B. directly proportional to the enzyme concentration
- C. inversely proportional to the enzyme concentration
- D. zero
Explanation: With substrate always available, every additional enzyme molecule adds its own turnover to the total, so doubling the enzyme doubles the…
Correct answer: directly proportional to the enzyme concentration- A. always occurs at the active site only
- B. can be reversed by adding more substrate
- C. involves the loss of the enzyme's three dimensional shape and is usually permanent
- D. increases the rate of the reaction
Explanation: Denaturation unfolds the whole protein, so the enzyme is destroyed as a catalyst and no amount of substrate will restore it, whereas most…
Correct answer: involves the loss of the enzyme's three dimensional shape and is usually permanent- A. 2
- B. 7
- C. 8
- D. 10
Explanation: Pepsin works optimally at pH 1.5-2 in the stomach, where it is activated by HCl.
Correct answer: 2- A. Temperature
- B. pH
- C. Substrate concentration
- D. Color of the solution
Explanation: Enzyme activity is affected by temperature, pH, substrate concentration, and presence of inhibitors/activators, but not by color.
Correct answer: Color of the solution- A. Substrate concentration increases
- B. Enzymes become denatured
- C. Product formation increases
- D. Temperature becomes constant
Explanation: Excess hydrogen or hydroxide ions disturb the ionic and hydrogen bonds between the side chains that hold the tertiary structure, so the…
Correct answer: Enzymes become denatured- A. Decrease the rate of reaction
- B. Increase the reaction rate until all active sites are saturated
- C. Have no effect on the reaction rate
- D. Increase the rate of reaction in a straight diagonal line
Explanation: Rate rises steeply at first because more collisions occur between substrate and free active sites, then levels off at Vmax once every site…
Correct answer: Increase the reaction rate until all active sites are saturated- A. 6
- B. 7
- C. 8
- D. 9
Explanation: Salivary amylase is suited to the nearly neutral pH of the mouth and loses its functional shape in strongly alkaline conditions, such as…
Correct answer: 9- A. increase in concentration of enzyme
- B. increase in concentration of substrate
- C. increase in pH
- D. increase in temperature
Explanation: When pH and temperature are already optimal and enzyme concentration is limiting, adding more enzyme provides more active sites and…
Correct answer: increase in concentration of enzyme- A. Activate
- B. Unaffected
- C. Denatured
- D. None of these
Explanation: Excessive heat disrupts the weak bonds that maintain an enzyme's three-dimensional shape, changing the active site and causing…
Correct answer: Denatured- A. Saturation
- B. Denaturation
- C. Composition
- D. Inhibition
Explanation: When adding more substrate no longer increases the reaction rate, the enzyme's active sites are saturated and are already occupied by…
Correct answer: Saturation- A. Enzymes get denatured at higher substrate conc
- B. Rate of reaction is indirectly proportional to substrate concentration at this point
- C. All the active sites on enzyme molecule are occupied
- D. None of these
Explanation: With a fixed enzyme concentration, increasing substrate eventually occupies all available active sites, so the enzymes are working at…
Correct answer: All the active sites on enzyme molecule are occupied- A. Increase in enzyme molecule increases the available active sites.
- B. This relation is for unlimited time period with unlimited enzyme concentration
- C. If the concentration is doubled the rate will become two fold.
- D. None of these.Chemistry
Explanation: The rate is approximately directly proportional to enzyme concentration only when sufficient substrate is available and other conditions…
Correct answer: This relation is for unlimited time period with unlimited enzyme concentration- A. There is probably more substrate present than there is enzyme.
- B. There is probably more enzayme available than there is substrate.
- C. There is probably more product present than there is either substrate or enzyme.
- D. The enzyme substrate complex is probably failing to form during the reaction
Explanation: If adding substrate increases the rate, the original reaction had substrate below the level needed to occupy all available active sites…
Correct answer: There is probably more enzayme available than there is substrate.Factors Affecting Enzyme Action MCQs: common questions
Are these Factors Affecting Enzyme Action MCQs free?
Yes. All Factors Affecting Enzyme Action MCQs from Biology are free on TestUstad, with unlimited attempts and no account needed. Nothing on this page is a sample or a trial.
How many Factors Affecting Enzyme Action MCQs are on this page?
There are 40 Factors Affecting Enzyme Action MCQs in the Biology bank, shown 20 to a page with the correct answer and an explanation on each.
Does every Factors Affecting Enzyme Action MCQ have an explanation?
Yes. Each Factors Affecting Enzyme Action question shows the correct option and a written explanation of why it is correct, so a wrong answer teaches you something rather than just being marked wrong.
Can I take a timed Factors Affecting Enzyme Action test?
Yes. The practice button on this page starts a free Factors Affecting Enzyme Action test drawn from the Biology bank. It marks each answer instantly, gives you a score at the end, and can be retaken as many times as you like.