All Free Biology MCQs with Answers
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19,844 questions · page 868 of 993
- A. Amylopsin
- B. Bain H1
- C. Arginase
- D. Peptidyl transferase
Explanation: Peptidyl transferase is an enzyme that is not protein in nature. It is a ribozyme, a catalytic RNA molecule found in the ribosome.
Correct answer: Peptidyl transferase- A. Enzymes are sharp in action than catalyst
- B. Catalysts used in large amount than enzymes
- C. Catalysts are inorganic while enzymes are organic in nature
- D. Enzymes need pH 1 while catalysts do not
Explanation: While catalysts can be organic or inorganic in nature, enzymes are only organic in nature.
Correct answer: Catalysts are inorganic while enzymes are organic in nature17343. It is false about enzymes:
- A. All enzymes require co-factors for proper functioning
- B. Only small amount of enzymes is required.
- C. They work in vitro as well as in vivo conditions
- D. They lower activation energy
Explanation: Co-factors are non-protein parts that are required for proper functioning of enzyme but some enzymes such as pepsin do not require…
Correct answer: All enzymes require co-factors for proper functioning17344. With the increase of enzyme concentration in a reaction, more_is/are available for the substrate.
- A. Binding sites
- B. Products
- C. Active site
- D. Activation energy
Explanation: When enzyme molecules increase there will be more active sites available for the binding of more substrates, due to which reaction rate…
Correct answer: Active site- A. Increase in rate of reaction
- B. Decrease in rate of reaction
- C. First increase then decrease in rate of reaction
- D. First increase then become constant
Explanation: The optimum temperature for the enzymes in human body is 37°C, When the temperature is increased from 30°C, the rate of reaction is also…
Correct answer: First increase then decrease in rate of reaction17346. Which type of bonds are mostly affected in an enzyme molecule when there are pH fluctuations?
- A. Ionic bonds
- B. Disulphide bonds
- C. Hydrogen bond
- D. Peptide Bond
Explanation: Hydrogen bond will have affected due to increasein temperature than optimum value, while change in pH will affects ionic bond.
Correct answer: Ionic bonds- A. Peptide bonds
- B. Disulphide bridges
- C. Hydrogen bonds
- D. Ionic bonds
Explanation: Heavy metals bind to the thiol (-SH) group of amino acids and break the disulphide brides between the amino acids.
Correct answer: Disulphide bridges- A. Lyases
- B. Ligase
- C. Hydrolases
- D. None of the above
Explanation: Lyases and ligases are enzymes involved in catalyzing biochemical reactions.
Correct answer: Hydrolases- A. α-ketoglutarate
- B. Malonate
- C. Pyruvate
- D. Oxaloacetate
Explanation: Malonate or oxaloacetate resemble succinate in structure and inhibit the activity of succinate dehydrogenase.
Correct answer: Malonate- A. Increasing Temperature
- B. Decreasing pH
- C. Decreasing Activation energy
- D. Increasing Activation energy
Explanation: Minimum amount of energy required to start a biochemical reaction is called activation energy.
Correct answer: Decreasing Activation energy- A. Binding site
- B. Active site
- C. Catalyst site
- D. Inhibition site
Explanation: An enzyme and its specific substrate react with each other through a definite charge-bearing site of an enzyme called the active site.
Correct answer: Active site- A. The contact between the substrate and the enzyme causes a change in the shape of the active site
- B. The shape of the substrate and the shape of the active site are complementary to each other
- C. The substrate fits into the active site and forms bonds with the amino acids at the active site
- D. All of the above options are correct
Explanation: Options B and C are common to both lock-and-key hypothesis and induced fit model.
Correct answer: The contact between the substrate and the enzyme causes a change in the shape of the active site- A. Concentration of enzyme
- B. Concentration of substrate
- C. Concentration of ES complex
- D. Concentration of inhibitor
Explanation: Non-competitive inhibitors don't bind to the active site of the enzyme; therefore, the concentration of enzyme, substrate, or ES complex…
Correct answer: Concentration of inhibitor17354. Which of the following strategies of enzymatic inhibition is used by noncompetitive inhibitors?
- A. Bind to substrate so that it cannot bind to the active site
- B. Target the enzyme for destruction using a protease
- C. Bind to the active site and prevent substrate from binding
- D. Bind to allosteric site to cause a conformational shift in the enzyme
Explanation: As summed up by the diagram, the binding of noncompetitive inhibitor causes alteration in the bonding of active site, as a result…
Correct answer: Bind to allosteric site to cause a conformational shift in the enzyme- A. Enzymes
- B. Reactant
- C. Product
- D. Substrate
Explanation: Inhibitors bind to the enzymes, and decrease their activity. They cannot bind to substrate, product or reactant.
Correct answer: Enzymes- A. Competitive inhibitors
- B. Noncompetitive inhibitors
- C. Irreversible inhibitors
- D. Both A and B
Explanation: Competitive inhibition is reversible because the inhibitor forms weak linkages with the enzyme.
Correct answer: Competitive inhibitors- A. Enzyme
- B. Substrate
- C. ES complex
- D. All of these
Explanation: Option C is correct since uncompetitive inhibition occurs when an inhibitor binds to an allosteric site of an enzyme, but only when the…
Correct answer: ES complex- A. Lock
- B. Key
- C. Both of these options are correct
- D. None of these options are correct
Explanation: Lock andkey model assumes that like a particular key opens a particular lock, a specific enzyme(key) acts upon a particular substrate…
Correct answer: Key- A. By adding activation energy requirements
- B. By lowering the activation energy requirements
- C. By decreasing the concentration of products
- D. By increasing the concentration of products
- E. All of the the given options
Explanation: Enzymes are biological catalysts that increase the rate of reaction by lowering the activation of the energy of the reactions.
Correct answer: By lowering the activation energy requirements- A. Irreversible inhibitors
- B. Competitive irreversible inhibitors
- C. Non-competitive inhibitors
- D. Reversible inhibitors
Explanation: Penicillin functions as a competitive inhibitor by mimicking the substrate that the bacterial enzyme would normally act upon, thus binding…
Correct answer: Competitive irreversible inhibitors