Free Characteristics of Enzymes MCQs with Answers
80 Characteristics of Enzymes MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Enzymes are globular biological catalysts that lower activation energy without being consumed, usually showing specificity for particular substrates. Questions cover active sites, enzyme substrate complexes, the lock and key and induced fit models, intracellular and extracellular action, and the effects of denaturation, while distinguishing enzymes from non biological catalysts.
Last updated
80 questions · page 1 of 4
1. A non-protein organic molecule that an enzyme needs in order to function, such as NAD, is called a
- A. cofactor metal ion
- B. coenzyme
- C. prosthetic group of a haemoglobin type
- D. substrate
Explanation: Coenzymes are organic helper molecules, often derived from vitamins, that bind loosely and carry chemical groups or electrons between…
Correct answer: coenzyme- A. They are consumed in the reactions they catalyse
- B. They remain chemically unchanged at the end of the reaction
- C. They can catalyse reactions that would otherwise be thermodynamically impossible
- D. They work equally well at every pH
Explanation: An enzyme releases the product and returns to its original state, ready to bind the next substrate molecule, which is why a small amount…
Correct answer: They remain chemically unchanged at the end of the reaction- A. globular proteins
- B. lipids
- C. polysaccharides
- D. nucleotides
Explanation: An enzyme is a globular protein whose precisely folded tertiary structure creates the active site, which is why anything that unfolds the…
Correct answer: globular proteins- A. coenzyme
- B. cofactor
- C. prosthetic group
- D. zymogen
Explanation: A zymogen, or proenzyme, carries an extra length of polypeptide that blocks the active site, and removing it activates the enzyme once it…
Correct answer: zymogen- A. dehydrogenase
- B. hydrolase
- C. isomerase
- D. ligase
Explanation: Enzymes are usually named from the substrate or the reaction plus the suffix ase, so a dehydrogenase removes hydrogen, as succinate…
Correct answer: dehydrogenase- A. starch into maltose
- B. protein into amino acids
- C. fat into fatty acids and glycerol
- D. hydrogen peroxide into water and oxygen
Explanation: A single catalase molecule can decompose millions of molecules of hydrogen peroxide per minute, which is necessary because the peroxide…
Correct answer: hydrogen peroxide into water and oxygen- A. a cofactor
- B. a coenzyme
- C. a prosthetic protein
- D. a substrate
Explanation: Cofactor is the term for an inorganic helper, and zinc in carbonic anhydrase and magnesium in the kinases of respiration are standard…
Correct answer: a cofactor- A. minerals absorbed from the soil
- B. vitamins of the B group
- C. fatty acids stored in adipose tissue
- D. the amino acids of the enzyme itself
Explanation: NAD is made from niacin, FAD from riboflavin and coenzyme A from pantothenic acid, so a deficiency of these vitamins cripples respiration…
Correct answer: vitamins of the B group- A. immobilised enzymes work at a much lower temperature
- B. immobilisation changes their specificity
- C. the enzyme can be recovered and reused and does not contaminate the product
- D. immobilised enzymes need no substrate
Explanation: Fixing the enzyme to beads or a membrane lets the product flow past and be collected pure, while the expensive enzyme stays behind for the…
Correct answer: the enzyme can be recovered and reused and does not contaminate the product- A. trypsin
- B. DNA polymerase
- C. catalase
- D. RNA polymerase
Explanation: The pancreas exports trypsin into the duodenum, where it digests food outside any cell.
Correct answer: trypsin11. The protein part of a conjugated enzyme, which on its own is catalytically inactive, is called the
- A. prosthetic group
- B. apoenzyme
- C. holoenzyme
- D. co-substrate
Explanation: The apoenzyme needs its non-protein partner, the cofactor, to become the active holoenzyme.
Correct answer: apoenzyme- A. lipid molecules with enzyme activity
- B. synthetic polymers made in the laboratory
- C. RNA molecules that catalyse reactions
- D. proteins permanently fixed to ribosomes
Explanation: The discovery that certain RNA molecules can catalyse reactions, such as self splicing, showed that not all enzymes are proteins.
Correct answer: RNA molecules that catalyse reactions- A. -ose
- B. -in
- C. -ol
- D. -ase
Explanation: Enzyme names end in -ase added to the substrate or reaction type, giving urease, lipase and dehydrogenase.
Correct answer: -ase- A. instability at body temperature
- B. gradual consumption during the reaction
- C. very high turnover number
- D. resistance to all inhibitors
Explanation: The turnover number is how many substrate molecules one enzyme molecule converts per second, and carbonic anhydrase has one of the highest…
Correct answer: very high turnover number15. Enzymes that catalyse the splitting of bonds with the addition of water belong to the class called
- A. hydrolases
- B. ligases
- C. transferases
- D. isomerases
Explanation: Hydrolases, such as amylase, lipase and peptidase, break bonds by inserting water.
Correct answer: hydrolases- A. They are consumed during the reaction
- B. They allow energetically impossible reactions to occur
- C. They increase the energy content of the products
- D. They are regenerated unchanged at the end of the reaction
Explanation: An enzyme leaves the reaction exactly as it entered, which is why tiny amounts can process huge quantities of substrate.
Correct answer: They are regenerated unchanged at the end of the reaction- A. permanently denatures the enzymes of microbes
- B. greatly reduces the rate of enzyme controlled reactions
- C. kills all bacteria and fungi at once
- D. changes the pH of the food
Explanation: Cold reduces the kinetic energy of molecules so enzyme catalysed spoilage reactions slow dramatically, but the enzymes are not destroyed…
Correct answer: greatly reduces the rate of enzyme controlled reactions- A. allosteric site
- B. active site
- C. cofactor site
- D. regulatory site
Explanation: The active site is a cleft formed by the folding of the chain, whose shape and chemistry fit the substrate.
Correct answer: active site- A. the active site is completely rigid
- B. the substrate changes its shape before binding
- C. enzymes have no binding site at all
- D. the active site moulds itself around the substrate as it binds
Explanation: Koshland argued in 1966 that binding itself induces a conformational change that tightens the fit and stresses bonds in the substrate…
Correct answer: the active site moulds itself around the substrate as it binds- A. enzyme
- B. substrate
- C. product
- D. coenzyme
Explanation: Emil Fischer's analogy pictures the enzyme's rigid active site as the lock and the substrate as the one key that fits it, explaining…
Correct answer: enzymeCharacteristics of Enzymes MCQs: common questions
Are these Characteristics of Enzymes MCQs free?
Yes. All Characteristics of Enzymes 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 Characteristics of Enzymes MCQs are on this page?
There are 80 Characteristics of Enzymes MCQs in the Biology bank, shown 20 to a page with the correct answer and an explanation on each.
Does every Characteristics of Enzymes MCQ have an explanation?
Yes. Each Characteristics of Enzymes 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 Characteristics of Enzymes test?
Yes. The practice button on this page starts a free Characteristics of Enzymes 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.