intro
Question 1:
What is an example of a competitive inhibitor?
Topic: Enzyme Inhibitors in Biochemistry
Correct Answer: D) Sulphonamide
- In the realm of biochemistry, competitive inhibitors are substances that bind to the active site of an enzyme.
- Sulphonamide is a classic example of a competitive inhibitor, as it competes with the substrate for the enzyme's active site.
- Other examples listed (Cyanide, Heavy Metals, Insecticides) are non-competitive inhibitors that bind to allosteric sites.
Question 2:
Which statement best describes the characteristics of enzymes?
Topic: Characteristics of Enzymes
Correct Answer: D) All of the above
- Enzymes are predominantly protein in nature, with the exception of ribozymes.
- These biological catalysts do not influence the equilibrium of a reaction, but they do accelerate the rate at which the reaction reaches equilibrium.
- Enzymes, being globular proteins, have the ability to lower the activation energy of a reaction.
Question 3:
What is the general pH range of enzymes urease and catalase?
Topic: Enzyme pH Levels
Correct Answer: C) 7
- Each enzyme has an optimal pH range at which it performs most efficiently.
- The enzymes urease and catalase have an optimal pH of approximately 7.
Question 4:
Which enzyme is responsible for converting H2O2 into H2O and O2, requiring 1 kJ/mol of energy?
Topic: Enzyme Reactions
Correct Answer: C) Catalase
- Certain enzymes specialize in specific chemical reactions.
- Catalase, in this case, facilitates the conversion of hydrogen peroxide (H2O2) into water (H2O) and oxygen (O2), a reaction requiring 1 kJ/mol of energy.
Question 5:
In the context of the lock and key hypothesis, what does an enzyme represent?
Topic: Enzyme Function and Structure
Correct Answer: A) A Lock
- The lock and key hypothesis provides a model for understanding enzyme function.
- In this analogy, the enzyme functions as the "lock" that can only be opened by the correct "key," which is the substrate.
Question 6:
What type of bond connects co-enzymes to enzymes?
Topic: Enzyme Structure
Correct Answer: D) Weak bond
- Co-enzymes attach to enzymes to assist in their function.
- They are typically connected through weak bonds, allowing them to be easily swapped or replaced as needed.
Question 7:
Where do non-competitive inhibitors bind on enzymes?
Topic: Enzyme Inhibitors
Correct Answer: C) Allosteric site
- Non-competitive inhibitors work by binding to an area on the enzyme other than the active site.
- This area is referred to as the allosteric site, and binding here changes the shape of the enzyme and hinders its ability to bind with its substrate.
Question 8:
Regarding enzymes, which of the following statements is accurate?
Topic: Enzyme Action
Correct Answer: D) They decrease the activation energy
- Enzymes, by their very nature, are proteins that facilitate biological reactions.
- They are well-known for their specificity, each designed to catalyze a particular reaction.
- Contrary to statement C, enzymes work by reducing, not increasing, the activation energy required for a reaction to occur.
MCQ 9:
What is the primary reason for an enzyme losing its catalytic activity at extremely high temperatures?
Topic: Enzyme Activity
Correct Answer: B) Denaturation
- Enzymes are sensitive to environmental conditions, including temperature.
- Extremely high temperatures can cause enzymes to lose their three-dimensional structure in a process known as denaturation.
- This process disrupts the active site of the enzyme, rendering it incapable of catalyzing its specific reaction.
- Therefore, the correct answer is B, "Denaturation".
MCQ 10:
What distinguishes catalysts from enzymes?
Topic: Catalysts vs Enzymes
Correct Answer: C) Catalysts are inorganic, while enzymes are organic in nature
- Both catalysts and enzymes speed up chemical reactions — but they differ in certain fundamental aspects.
- The most significant difference lies in their nature: catalysts are typically inorganic substances, while enzymes are organic.
- Thus, the correct answer is C, "Catalysts are inorganic, while enzymes are organic in nature".
MCQ 11:
Which substances are considered non-competitive inhibitors?
Topic: Non-competitive Inhibitors
Correct Answer: D) All of the above
- Non-competitive inhibitors are substances that hinder enzyme activity not by blocking the active site but by binding to an alternate site called the allosteric site.
- Examples of such inhibitors include cyanide, heavy-metal ions, and insecticides.
- Therefore, all the options listed act as non-competitive inhibitors, making the correct answer D, "All of the above".
MCQ 12:
What is the impact on enzyme activity when the temperature is reduced to 0°C?
Topic: Temperature and Enzyme Activity
Correct Answer: B) The activity is minimized
- Enzyme activity is closely linked to temperature, with each enzyme having a specific optimal temperature for maximum activity.
- At extremely low temperatures like 0°C, enzyme activity is significantly reduced, but it does not reach zero nor causes the enzyme to denature.
- Thus, the most accurate answer is B, "The activity is minimized".
MCQ 13:
What term is used to describe a substance that accelerates a chemical reaction without being a reactant itself?
Topic: Reaction Accelerators
Correct Answer: A) Enzyme
- Both enzymes and catalysts speed up reactions, but the context of use may differ.
- Enzymes, which are biological catalysts, are used in life processes.
- If the context is a biological system, then the term "enzyme" is more appropriate. Hence, the correct answer is A, "Enzyme".
MCQ 14:
What term is used to define the energy needed to initiate a reaction?
Topic: Reaction Initiation Energy
Correct Answer: C) Activation Energy
- Every chemical reaction requires a certain amount of energy to get started.
- This is referred to as the activation energy, which is the minimum energy that must be provided to the reactants before they can transform into products.
- Therefore, the correct answer is C, "Activation Energy".
MCQ 15:
Which of the following compounds is recognized as a co-enzyme?
Topic: Co-enzymes
Correct Answer: D) All of the above
- Co-enzymes are organic molecules that assist enzymes in the chemical reactions they catalyze.
- NAD, FAD, and NADP are examples of co-enzymes that play crucial roles in numerous biochemical processes.
- Consequently, the correct answer is D, "All of the above".
MCQ 16:
What is the pH range of the invertase enzyme?
Topic: Enzyme pH Range
Correct Answer: B) 4.5
- The activity of enzymes is heavily influenced by the pH of their environment.
- Each enzyme has a specific pH at which it performs optimally.
- For invertase, this optimal pH is 4.5, which makes the correct answer B, "4.5".
Question 17:
Within what pH range does the enzyme pepsin function optimally?
Topic: Optimal pH for Pepsin
Correct Answer: D) 2
- The enzymatic activity of pepsin, like other enzymes, is highly dependent on the pH of its environment.
- Pepsin functions optimally in highly acidic conditions, specifically at a pH of 2.
- Therefore, the correct answer is D, "2".
Question 18:
Among the following co-enzymes, which one exhibits the highest potency?
Topic: Potency of Co-enzymes
Correct Answer: A) NAD
- Co-enzymes are organic molecules that aid enzymes in catalyzing reactions.
- NAD, known for its crucial role in redox reactions, is considered to have a high potency among co-enzymes.
- Thus, the correct answer is A, "NAD".
Question 19:
What happens to the rate of a reaction as the concentration of the enzyme increases?
Topic: Enzyme Concentration and Reaction Rate
Correct Answer: B) The rate increases linearly
- The rate of a biochemical reaction can be affected by various factors, one of which is the concentration of the enzyme catalyzing the reaction.
- As the concentration of the enzyme increases, the rate of the reaction increases linearly due to the availability of more enzyme molecules to catalyze the reaction.
- Hence, the appropriate answer is B, "The rate increases linearly".
Question 20:
What term is used to define the inactive form of an enzyme when the co-enzyme is removed?
Topic: Apoenzymes
Correct Answer: A) Proteins
- Apoenzyme is the protein component of an enzyme to which a co-enzyme can attach, forming an active enzyme.
- It is inactive because a co-enzyme or a prosthetic group needs to bind to it for activation.
- Thus, the accurate answer is A, "Proteins".
Question 21:
What components make up an enzyme's active site?
Topic: Active Site Components
Correct Answer: C) Both A and B
- An enzyme's active site is composed of a binding site and a catalytic site.
- The binding site ensures that the substrate molecules are correctly aligned for the reaction, while the catalytic site contains the residues that directly participate in the making and breaking of bonds.
- Therefore, the correct answer is C, "Both A and B".
Question 22:
What is the non-protein organic component of an enzyme referred to as?
Topic: Non-Protein Organic Component of Enzymes
Correct Answer: A) Co-enzyme
- In an enzyme, the non-protein organic component that assists in the enzyme's function is called a co-enzyme.
- Co-enzymes carry chemical groups between enzymes and often act as an intermediate carrier of electrons, hydrogen atoms, or functional groups in metabolic reactions.
- Therefore, the accurate answer is A, "Co-enzyme".
Question 23:
What is the nature of a biological catalyst?
Topic: Nature of Biological Catalysts
Correct Answer: A) Protein
- Biological catalysts, also known as enzymes, are mainly composed of proteins which expedite biochemical reactions.
- They are not composed of lipids, carbohydrates, or nucleic acids.
- Consequently, the correct answer is A, "Protein".
Question 24:
Which model suggests that the structure of an enzyme undergoes minor alterations?
Topic: Enzyme Structure Alterations
Correct Answer: C) Induced - Fit Model
- The Induced - Fit Model suggests that the active site of an enzyme changes slightly to accommodate the binding of a substrate.
- Neither the Key - Lock Model nor the Hand - Glove Model propose any structural changes in the enzyme upon substrate binding.
- Therefore, the correct answer is C, "Induced - Fit Model".
Question 25:
Considering the reaction (2H2O2 ⟶ 2H2O + O2), which has an activation energy of 86 kJ/mol without a catalyst. What will be the activation energy if the same reaction occurs in the presence of an enzyme?
Topic: Activation Energy with Enzyme
Correct Answer: D) 1 kJ/mol
- Enzymes are known to reduce the activation energy required for a reaction, thereby speeding it up.
- In this case, the enzyme catalase is present, which significantly reduces the activation energy to just 1 kJ/mol.
- Hence, the appropriate answer is D, "1 kJ/mol".
Question 26:
Where within an enzyme does the reaction take place?
Topic: Enzyme Reaction Site
Correct Answer: C) Active Site
- The part of an enzyme where the reaction takes place is referred to as the active site.
- The active site is not a substrate, nor a co-enzyme. It is a specific region on an enzyme where the substrate binds and the reaction occurs.
- Consequently, the right answer is C, "Active Site".
Question 27:
In which year was the Lock and Key hypothesis proposed by Fischer?
Topic: Lock and Key Hypothesis
Correct Answer: B) 1890
- The Lock and Key hypothesis, a theory explaining enzyme-substrate interaction, was proposed by Emil Fischer.
- This hypothesis was not proposed in 1790, 1990, or 1999, but in the year 1890.
- Therefore, the correct answer is B, "1890".
Question 28:
Based on the Lock and Key model of the enzyme, how is the active site of an enzyme described?
Topic: The Active Site in the Lock and Key Model
Correct Answer: D) Rigid
- According to the Lock and Key model, an enzyme's active site is rigid, like a lock awaiting a specific key.
- It is not described as elastic, flexible, or extendable in this model.
- Therefore, the right answer is D, "Rigid".
Question 29:
What type of bonds are typically formed between enzymes and substrates?
Topic: Bonding between Enzymes and Substrates
Correct Answer: D) Covalent
- While forming a complex, enzymes and substrates can be held together by various bonds, including ionic, hydrogen, and covalent.
- In some cases, a strong covalent bond is formed, which holds the enzyme and substrate together.
- Consequently, the appropriate answer is D, "Covalent".
Question 30:
What is the composition of an enzyme?
Topic: Enzyme Composition
Correct Answer: C) Both A and B
- An enzyme is composed of both a framework and an active site.
- The framework provides the structural support, while the active site is where the substrate binds and the chemical reaction occurs.
- Therefore, the correct answer is C, "Both A and B".
Question 31:
What is the study of enzymes called?
Topic: Study of Enzymes
Correct Answer: C) Enzymology
- The study of enzymes, their nature, activity, and impact on biological reactions, is termed enzymology.
- It is not referred to as mycology (study of fungi), phycology (study of algae), or ornithology (study of birds).
- Hence, the right answer is C, "Enzymology".
Question 32:
What is the typical physiological pH range for most enzymes?
Topic: Physiological pH for Enzymes
Correct Answer: A) 7-8
- Enzymes function optimally within a specific pH range known as the physiological pH.
- The majority of enzymes have a physiological pH of 7-8, which is neutral to slightly alkaline.
- As such, the correct answer is A, "7-8".
MCQ 33:
What suffix is generally added to a substance to name an enzyme?
Topic: Nomenclature of Enzymes
Correct Answer: D) ASE
- The usual practice in scientific taxonomy is to add a specific suffix to the name of the substance upon which an enzyme acts.
- In the case of enzymes, this suffix is typically "ase".
- Therefore, the correct answer is D, "ASE".
MCQ 34:
How do enzymes affect activation energy?
Topic: Enzymes and Activation Energy
Correct Answer: B) Decrease
- Enzymes play a crucial role in biochemical reactions by influencing the activation energy - the energy requirement for a reaction to occur.
- Instead of increasing, fluctuating, or having no effect, enzymes decrease the activation energy, making reactions more efficient.
- Consequently, the correct answer is B, "Decrease".
MCQ 35:
How many types of reactions can a specific enzyme catalyze?
Topic: Reaction Specificity of Enzymes
Correct Answer: A) Only one
- Each enzyme is designed to catalyze a specific reaction type.
- It's not accurate that an enzyme can catalyze two or multiple reactions, and certainly, an enzyme is not inactive.
- Therefore, the correct response is A, "Only one".
MCQ 36:
What is the optimum temperature for the arctic snow flea?
Topic: Optimum Temperature for Arctic Snow Flea
Correct Answer: D) -10°C
- The optimum temperature for a specific organism refers to the temperature at which it thrives best.
- In the case of the arctic snow flea, this temperature is not a positive value but rather a below-freezing point.
- Hence, the correct answer is D, "-10°C".
MCQ 37:
What are co-enzymes derived from?
Topic: Origin of Co-Enzymes
Correct Answer: C) Both A and B
- Co-enzymes play a pivotal role in enzyme function, and they are derived from specific substances.
- These include vitamins as well as minerals, thus ruling out the options of vitamins or minerals alone, and certainly not none of these.
- Consequently, the accurate answer is C, "Both A and B".
MCQ 38:
Which factor listed below does not influence the rate of enzymatic action?
Topic: Factors Affecting Enzyme Action
Correct Answer: B) Intensity of light
- Enzyme activity can be affected by several factors, including enzyme concentration, substrate concentration, and temperature.
- However, light intensity is not among these factors and does not have a significant effect on enzyme action.
- So, the correct answer is B, "Intensity of light".
MCQ 39:
What is the optimum pH for urease?
Topic: Optimum pH for Urease
Correct Answer: D) 7
- Each enzyme has an optimal pH at which it functions most effectively. For urease, this is not in the highly acidic (2) or highly alkaline (15-16) range, nor at pH 4.5.
- The optimum pH for urease is 7, which is neutral.
- Therefore, the right answer is D, "7".
MCQ 40:
What is the term for a substance that reversibly alters the activity of an enzyme by binding at a location other than the active site?
Topic: Enzyme Modulation
Correct Answer: C) Allosteric Modulator
- Some substances can modify enzyme activity by attaching themselves at a position other than the enzyme's active site.
- They are not Competitive Inhibitors or Catalytic Inhibitors, which are involved with the active site.
- These are called Allosteric Modulators because they bind to the allosteric site. Hence, the correct answer is C, "Allosteric Modulator".
MCQ 41:
Who dismissed the Lock and Key model?
Topic: Enzyme Theory Origins
Correct Answer: B) D.E. Koshland
- The Lock and Key model was an early theory in enzyme action.
- The person who dismissed this model was not E. Fischer, Fredor, or R. Martin.
- It was D.E. Koshland who rejected this model, offering a more dynamic interpretation of enzyme-substrate interaction. So, the correct answer is B, "D.E. Koshland".
MCQ 42:
Who is the proponent of the Lock and Key theory of enzyme action?
Topic: Proponents of Enzyme Theories
Correct Answer: A) Emil Fisher
- The Lock and Key theory, which describes enzymes and substrates as fitting together like a lock and key, was proposed by a specific scientist.
- This scientist was not Koshland, Payen, or Buchner.
- It was Emil Fisher who first introduced this theory in the late 19th century. Thus, the correct answer is A, "Emil Fisher".
MCQ 43:
Who is the author of the Induced Fit hypothesis?
Topic: Enzyme Interaction Hypotheses
Correct Answer: B) David Koshland
- The Induced Fit hypothesis is an important concept in enzymology that provides a more flexible model for enzyme-substrate interaction.
- This hypothesis was not proposed by Emil Fisher, Wilhelm Kuhne, or Anselme Payen.
- David Koshland is the scientist behind this important hypothesis, making B, "David Koshland" the correct answer.
MCQ 44:
What is the total amount of energy required to convert H2O2 to H2O in the absence of an enzyme?
Topic: Energy Requirements in Chemical Reactions
Correct Answer: B) 86 kJ/mole
- The conversion of H2O2 into H2O involves a chemical reaction that requires a certain amount of energy.
- This energy requirement is neither as low as 1 kJ/mole nor is it zero.
- The correct energy required for this conversion is 86 kJ/mole, therefore, the right answer is B, "86 kJ/mole".
MCQ 45:
What term is used to denote the minimum amount of energy necessary to trigger a reaction?
Topic: Energy in Chemical Reactions
Correct Answer: C) Activation energy
- Every chemical reaction requires a certain amount of energy to get started.
- This is not referred to as excitatory or inhibitory energy, nor is it without a specific term.
- This initial required energy is called "Activation energy". Hence, the correct answer is C, "Activation energy".