Nelson Biology 12 Section 1.4: Enzymes Quiz

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Nelson Biology 12 Section 1.4: Enzymes Quiz - Quiz

This quiz is based on the content within the Nelson Biology 12 textbook. Enzymes are both proteins and biological catalysts produced by living organisms, and these catalysts accelerate various chemical reactions. This test consists of 28 questions of the same from section 1.4 of the book.


Questions and Answers
  • 1. 

    Enzymes are protein catalysts. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    Enzymes are indeed protein catalysts. They are specialized proteins that speed up chemical reactions in living organisms by lowering the activation energy required for the reaction to occur. Enzymes are highly specific in their function and can catalyze a wide range of biochemical reactions. Therefore, the statement "Enzymes are protein catalysts" is true.

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  • 2. 

    Defined, a catalyst is:

    • A.

      A substance that speeds up a chemical reaction, but is consumed in the process

    • B.

      A substance that slows down a chemical reaction, without being consumed in the process

    • C.

      A substance that speeds up a chemical reaction, without being consumed in the process

    • D.

      A substance that slows down a chemical reaction, but is consumed in the process

    Correct Answer
    C. A substance that speeds up a chemical reaction, without being consumed in the process
    Explanation
    A catalyst is a substance that speeds up a chemical reaction without being consumed in the process. It lowers the activation energy required for the reaction to occur, allowing it to proceed more quickly. The catalyst itself remains unchanged at the end of the reaction and can be used again in future reactions.

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  • 3. 

    In catalyzed reactions, the reactants are converted into products much slower than they would without a catalyst. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    In catalyzed reactions, the reactants are converted into products much faster than they would without a catalyst.

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  • 4. 

    What must happen in a reaction for new bonds to be created between the atoms of product molecules?1. Reactant molecules must collide with enough force2. The reactant molecules should be a certain temperature to move accordingly3. Molecules must collide with the correct geometric orientation for bond breaking to occur4. The product molecules must be moving fast enough

    • A.

      1 and 2

    • B.

      2 and 3

    • C.

      1 and 3

    • D.

      2 and 4

    Correct Answer
    C. 1 and 3
    Explanation
    In order for new bonds to be created between the atoms of product molecules, two conditions must be met. First, reactant molecules must collide with enough force. This force allows for the breaking of existing bonds and the formation of new ones. Second, molecules must collide with the correct geometric orientation. This means that the atoms involved in the reaction must align in a specific way in order for the bonds to be properly formed. Therefore, the correct answer is 1 and 3.

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  • 5. 

    Some reactions possess an activation energy barrier that must be overcome for the reaction to occur. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    True. Some reactions require an input of energy to overcome an activation energy barrier before they can proceed. This activation energy barrier represents the energy required to break bonds in the reactant molecules and initiate the reaction. Once the activation energy barrier is overcome, the reaction can proceed spontaneously. Therefore, the statement is true.

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  • 6. 

    Heat provides the ____________ ____________ for many reactions. It increases the rate of reaction.

    Correct Answer
    activation energy
    Explanation
    Heat provides the necessary energy for many reactions to occur, which is known as activation energy. When heat is applied to a system, it increases the kinetic energy of the molecules, allowing them to move faster and collide more frequently. This increased collision rate leads to a higher likelihood of successful collisions and therefore an increased rate of reaction. Activation energy is the minimum amount of energy required for a reaction to take place, and heat is a common source of this energy.

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  • 7. 

    Why can't living cells use heat to provide the activation energy for their reactions?1. Heat is not readily available to all living cells2. Heat at excessive amounts denatures proteins3. When a critical point of heat level is reached, the proteins and cell can lose their function4. Heat doesn't provide the activation energy for their reactions

    • A.

      1 and 4

    • B.

      3 and 4

    • C.

      1 and 3

    • D.

      2 and 3

    Correct Answer
    D. 2 and 3
    Explanation
    Living cells cannot use heat to provide the activation energy for their reactions because excessive amounts of heat can denature proteins, causing them to lose their function. When the heat level reaches a critical point, both proteins and cells can lose their functionality. Additionally, heat itself does not provide the activation energy required for reactions to occur. Therefore, the correct answer is 2 and 3.

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  • 8. 

    Living cells can rely on high levels of heat as a source of activation energy. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    Living cells cannot rely on high levels of heat as a source of activation energy.

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  • 9. 

    ___________________ allow reactions to proceed at suitable rates at moderate temperatures by reducing the activation energy barrier.

    Correct Answer
    Catalysts, catalysts
    Explanation
    Catalysts are substances that facilitate chemical reactions by lowering the activation energy required for the reaction to occur. They do this by providing an alternative reaction pathway with a lower energy barrier. This allows reactions to proceed at moderate temperatures, which is beneficial as high temperatures can be costly and may lead to unwanted side reactions. Catalysts themselves are not consumed in the reaction and can be used repeatedly. Therefore, they are essential in many industrial processes to increase reaction rates and improve efficiency.

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  • 10. 

    A catalyst speeds up endergonic and exergonic reactions by heightening the activation energy. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    A catalyst speeds up endergonic and exergonic reactions by lowering the activation energy.

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  • 11. 

    A catalyst speeds up endergonic and exergonic reactions by lowering the activation energy, but it does not change the value of delta G. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    A catalyst is a substance that speeds up a chemical reaction by lowering the activation energy required for the reaction to occur. This means that the reaction can proceed more quickly and with less energy input. However, a catalyst does not change the overall energy change of the reaction, which is represented by delta G. Therefore, the statement that a catalyst does not change the value of delta G is true.

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  • 12. 

    Catalysts ________________ the potential energy level of the transition state, and, thus, allow a greater proportion of colliding reactants to reach the transition state and become products.

    Correct Answer
    decrease, lower, minimize
    Explanation
    Catalysts decrease the potential energy level of the transition state, which means they lower or minimize it. This allows a greater proportion of colliding reactants to reach the transition state and become products.

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  • 13. 

    Catalysts work by reducing the activation energy, thereby speeding up forward and reverse reactions at different rates. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    Catalysts work by reducing the activation energy, thereby speeding up forward and reverse reactions equally/at the same rate.

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  • 14. 

    Catalysts do not affect the position of equilibrium. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    Catalysts do not affect the position of equilibrium because they do not change the relative amounts of reactants and products in a chemical reaction. Instead, catalysts only increase the rate at which the reaction reaches equilibrium by providing an alternative reaction pathway with lower activation energy. Thus, the equilibrium constant and the position of equilibrium remain unaffected by the presence of a catalyst.

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  • 15. 

    Defined, a substrate is:

    • A.

      The reactant that an enzyme acts on when it catalyzes a chemical reaction

    • B.

      The product that an enzyme acts on when it catalyzes a chemical reaction

    • C.

      A and B

    • D.

      None of the above

    Correct Answer
    A. The reactant that an enzyme acts on when it catalyzes a chemical reaction
    Explanation
    A substrate is the reactant that an enzyme acts on when it catalyzes a chemical reaction. Enzymes are proteins that speed up chemical reactions by binding to specific molecules, called substrates, and converting them into products. The substrate is the molecule that the enzyme acts upon and undergoes a chemical change during the reaction. Therefore, the correct answer is the first option: "The reactant that an enzyme acts on when it catalyzes a chemical reaction."

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  • 16. 

    The substrate binds to a particular site on the enzyme to which it is attracted. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    Enzymes have a specific region called the active site where the substrate molecule binds. This binding is based on the attraction between the substrate and the active site. Therefore, the statement that the substrate binds to a particular site on the enzyme to which it is attracted is true.

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  • 17. 

    Enzymes are proteins in tertiary or quaternary structure with simple conformations. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    Enzymes are proteins in tertiary or quaternary structure with complex conformations.

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  • 18. 

    Enzymes are very specific for the substrate to which they bind. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    Enzymes are indeed very specific for the substrate to which they bind. This specificity is due to the unique shape and chemical properties of both the enzyme and the substrate. Enzymes have an active site that is perfectly complementary to the shape and properties of the substrate, allowing them to bind together like a lock and key. This specificity ensures that enzymes only catalyze specific reactions and do not interact with other molecules in the cell. Therefore, the statement "Enzymes are very specific for the substrate to which they bind" is true.

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  • 19. 

    In enzyme-catalyzed reactions, the substrate binds to a very small portion of the enzyme, called the:

    • A.

      Binding site

    • B.

      Active site

    • C.

      Inactive site

    • D.

      Bonding site

    Correct Answer
    B. Active site
    Explanation
    Enzyme-catalyzed reactions involve the substrate binding to a specific region on the enzyme known as the active site. This is where the chemical reaction takes place, and the active site is usually a small and specific region of the enzyme that is complementary in shape and charge to the substrate. The binding of the substrate to the active site allows for the formation of enzyme-substrate complexes, which facilitate the conversion of the substrate into the product. The active site plays a crucial role in catalyzing the reaction by providing a suitable environment for the reaction to occur and promoting the formation of the transition state.

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  • 20. 

    The substrate and active site must contain distinctive shapes for binding to occur. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    The substrate and active site must contain compatible/similar shapes for binding to occur.

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  • 21. 

    As the substrate enters the active site, its functional groups come close to the functional groups of a number of amino acids. What happens as a result?

    • A.

      The protein and substrate repel

    • B.

      The protein changes its shape to accommodate the substrate

    • C.

      The protein closes off its active site to the substrate

    • D.

      The substrate enters the active site of the protein, and nothing changes

    Correct Answer
    B. The protein changes its shape to accommodate the substrate
    Explanation
    When the substrate enters the active site, its functional groups come close to the functional groups of a number of amino acids. As a result, the protein undergoes a conformational change, altering its shape to accommodate the substrate. This change in shape allows for optimal binding between the protein and substrate, facilitating the catalytic reaction.

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  • 22. 

    'A model of enzyme activity that describes an enzyme as a dynamic protein molecule that changes shape to better accommodate the substrate' is the definition of the following term:

    • A.

      Enzyme model

    • B.

      Substrate model

    • C.

      Induced-fit model

    • D.

      Catalyst model

    Correct Answer
    C. Induced-fit model
    Explanation
    The induced-fit model is a model of enzyme activity that describes how enzymes change their shape to better accommodate the substrate. This model suggests that the enzyme and substrate undergo conformational changes upon binding, leading to a more optimal fit between the two. This change in shape allows for better interaction and catalysis of the substrate, resulting in the formation of the product. The induced-fit model helps to explain the specificity and efficiency of enzyme-substrate interactions.

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  • 23. 

    The attachment of the substrate to the enzyme's active site creates the:

    • A.

      Enzyme-substrate complex

    • B.

      Substrate complex

    • C.

      Enzyme complex

    • D.

      Catalyst complex

    Correct Answer
    A. Enzyme-substrate complex
    Explanation
    When the substrate binds to the active site of an enzyme, it forms an enzyme-substrate complex. This complex allows the enzyme to catalyze the reaction by bringing the substrate molecules into close proximity and providing the necessary environment for the reaction to occur. The enzyme-substrate complex is a temporary intermediate state in the enzymatic reaction, and it is essential for the enzyme to function effectively in facilitating the conversion of substrates to products. Therefore, the correct answer is enzyme-substrate complex.

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  • 24. 

    How do enzymes decrease the energy of activation?

    • A.

      Stretching the chemical bonds

    • B.

      Bending the chemical bonds

    • C.

      All of the above

    • D.

      None of the above

    Correct Answer
    C. All of the above
    Explanation
    Enzymes decrease the energy of activation by both stretching and bending the chemical bonds. Stretching the bonds weakens them, making it easier for the reaction to proceed. Bending the bonds also lowers the energy barrier by bringing the reactants into a more favorable orientation for the reaction to occur. Therefore, both stretching and bending contribute to the enzymatic decrease in energy of activation.

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  • 25. 

    Heat energy is provided by the cell's internal environment that helps to bring the substrate molecule to the transition state. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    The statement is true because heat energy from the cell's internal environment is necessary to provide the necessary activation energy for a substrate molecule to reach the transition state. This energy allows the chemical reaction to occur and for the substrate molecule to be converted into the product. Without heat energy, the reaction would proceed at a much slower rate or may not occur at all. Therefore, the heat energy provided by the cell's internal environment is crucial for facilitating the reaction.

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  • 26. 

    Sometimes, a low pH environment in the active site is needed for certain reactions to take place. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    Certain reactions require a low pH environment in the active site for them to occur. This is because the presence of a low pH environment can facilitate the necessary chemical reactions by providing the optimal conditions for the reaction to proceed. In such cases, a low pH environment can enhance the activity of enzymes or promote the formation of reactive intermediates, enabling the reaction to take place. Therefore, the statement "Sometimes, a low pH environment in the active site is needed for certain reactions to take place" is true.

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  • 27. 

    The speed at which a catalyzed reaction proceeds can increase indefinitely by increasing the concentration of the substrate. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    The speed at which a catalyzed reaction proceeds cannot increase indefinitely by increasing the concentration of the substrate.

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  • 28. 

    An increase in temperature results in an:

    • A.

      Increase in speed of enzyme activity

    • B.

      Increase in concentration of enzyme activity

    • C.

      All of the above

    • D.

      None of the above

    Correct Answer
    A. Increase in speed of enzyme activity
    Explanation
    An increase in temperature can cause the molecules in an enzyme to move faster, which in turn increases the speed of enzyme activity. This is because higher temperatures provide more energy for the enzyme-substrate interactions, allowing the reactions to occur at a faster rate. However, it is important to note that there is an optimal temperature for enzyme activity, and beyond this point, further increases in temperature can denature the enzyme and decrease its activity.

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  • 29. 

    What happens to the structure of the protein when the critical point of temperature is reached?

    • A.

      Denaturation

    • B.

      Loss of enzyme function

    • C.

      Disruption of protein structure

    • D.

      All of the above

    Correct Answer
    D. All of the above
    Explanation
    When the critical point of temperature is reached, the protein undergoes denaturation, which refers to the unfolding and disruption of its structure. This leads to the loss of enzyme function, as the active site of the protein becomes distorted and unable to bind to its substrate properly. Therefore, all of the options mentioned in the answer, including denaturation, loss of enzyme function, and disruption of protein structure, are correct.

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  • 30. 

    Every enzyme has an optimal temperature and pH. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    Enzymes are highly sensitive to changes in temperature and pH. Each enzyme has an optimal temperature and pH at which it functions most efficiently. Deviating from this optimal range can cause a decrease in enzyme activity and ultimately affect its ability to catalyze reactions. Therefore, it is true that every enzyme has an optimal temperature and pH.

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  • 31. 

    Most human enzymes work best at around what temperature?

    • A.

      27 degrees Celsius

    • B.

      37 degrees Celsius

    • C.

      47 degrees Celsius

    • D.

      37 degrees Fahrenheit

    Correct Answer
    B. 37 degrees Celsius
    Explanation
    Most human enzymes work best at around 37 degrees Celsius because this is the average body temperature of humans. Enzymes are proteins that act as catalysts in biological reactions, and they have an optimal temperature at which they function most efficiently. Since the human body operates at around 37 degrees Celsius, it is logical that human enzymes have evolved to work best at this temperature. Deviations from this temperature can affect the enzyme's structure and function, leading to potential inefficiencies or denaturation.

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  • 32. 

    'These are so similar to the enzyme's substrate that they are able to enter the enzyme's active site and block the normal substrate from binding.' This is the definition of which term?

    • A.

      Noncompetitive inhibitors

    • B.

      Allosteric inhibitors

    • C.

      Competitive inhibitors

    • D.

      None of the above

    Correct Answer
    C. Competitive inhibitors
    Explanation
    Competitive inhibitors are molecules that closely resemble the substrate of an enzyme and are able to bind to the enzyme's active site. This prevents the normal substrate from binding and inhibits the enzyme's activity. The definition provided in the question aligns with the characteristics of competitive inhibitors, making it the correct answer. Noncompetitive inhibitors, on the other hand, bind to a different site on the enzyme and do not directly compete with the substrate. Allosteric inhibitors also bind to a different site on the enzyme, causing a conformational change that inhibits the enzyme's activity.

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  • 33. 

    Competitive inhibitors compete with substrates to enter the enzyme's ___________ site.

    Correct Answer
    active, Active
    Explanation
    Competitive inhibitors are molecules that have a similar shape and structure to the substrate, allowing them to bind to the active site of the enzyme. By occupying the active site, the competitive inhibitor blocks the substrate from binding and prevents the enzyme from catalyzing the reaction. Therefore, competitive inhibitors compete with substrates to enter the enzyme's active site. The repetition of the word "active" in the answer emphasizes the importance of the active site in this process.

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  • 34. 

    Competitive inhibitors promote the binding of the enzyme's substrate to the active site. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    Competitive inhibitors block the binding of the enzyme's substrate to the active site.

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  • 35. 

    How can the process of competitive inhibitors binding to the active site be reversed?

    • A.

      Increase the concentration of the enzyme's substrate

    • B.

      Increase the concentration of the competitive inhibitors

    • C.

      Increase the temperature

    • D.

      All of the above

    Correct Answer
    A. Increase the concentration of the enzyme's substrate
    Explanation
    Increasing the concentration of the enzyme's substrate can reverse the process of competitive inhibitors binding to the active site because competitive inhibitors compete with the substrate for binding to the active site. By increasing the substrate concentration, there will be more substrate molecules available to bind to the active site, effectively outcompeting the inhibitors and reversing their binding. This will allow the enzyme to function normally and carry out its catalytic activity. Increasing the concentration of the inhibitors or the temperature would not reverse the binding of competitive inhibitors to the active site.

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  • 36. 

    'These do not compete with an enzyme's substrate for the active site. Instead, they attach to another site on the enzyme, causing a change in the enzyme's shape.' This is the definition of what term?

    • A.

      Noncompetitive inhibitors

    • B.

      Allosteric inhibitors

    • C.

      Competitive inhibitors

    • D.

      None of the above

    Correct Answer
    A. Noncompetitive inhibitors
    Explanation
    Noncompetitive inhibitors are molecules that do not directly compete with the substrate for the active site of an enzyme. Instead, they bind to a different site on the enzyme called the allosteric site, causing a conformational change in the enzyme's shape. This change in shape prevents the enzyme from functioning properly, reducing or inhibiting its activity. Therefore, the given definition accurately describes noncompetitive inhibitors.

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  • 37. 

    Noncompetitive inhibitors have the ability to change the shape of the active site in such a way that it loses affinity for its substrate. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    Noncompetitive inhibitors can bind to an enzyme at a site other than the active site, causing a conformational change in the enzyme. This change in shape can result in the active site losing its affinity for the substrate, preventing the enzyme from catalyzing the reaction. Therefore, the statement that noncompetitive inhibitors have the ability to change the shape of the active site in such a way that it loses affinity for its substrate is true.

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  • 38. 

    The inhibitor may affect those parts of the active site that perform the work of catalysis, resulting in a loss of enzyme activity. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    The statement is true because inhibitors can indeed affect the active site of an enzyme. The active site is the region where the catalysis of a reaction takes place. Inhibitors can bind to the active site and disrupt the normal functioning of the enzyme, leading to a loss of enzyme activity. This can happen by blocking the substrate from binding to the active site or by altering the shape or structure of the active site, preventing the enzyme from carrying out its catalytic function effectively.

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  • 39. 

    Inhibitors can be produced by the cell to:

    • A.

      Regulate activity

    • B.

      Act as poison

    • C.

      All of the above

    • D.

      None of the above

    Correct Answer
    C. All of the above
    Explanation
    Inhibitors can be produced by the cell to regulate activity by slowing down or stopping certain processes. They can also act as poison by inhibiting the activity of enzymes or other proteins that are essential for cell function. Therefore, the correct answer is "All of the above" because inhibitors can serve both regulatory and toxic functions within the cell.

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  • 40. 

    Cells must control enzyme activity to coordinate cell activities. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    Cells must control enzyme activity to coordinate cell activities. This is true because enzymes play a crucial role in various cellular processes such as metabolism, signaling, and gene expression. Without proper control of enzyme activity, cells would not be able to regulate these processes effectively, leading to dysfunction and imbalance. Therefore, controlling enzyme activity is essential for coordinating cell activities and maintaining cellular homeostasis.

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  • 41. 

    How can cells control enzyme activity?1. Inhibiting the enzyme's action2. Blocking off all active sites3. Blocking off all allosteric sites4. Restricting the production

    • A.

      3 and 4

    • B.

      1 and 3

    • C.

      2 and 4

    • D.

      1 and 4

    Correct Answer
    D. 1 and 4
    Explanation
    Cells can control enzyme activity by inhibiting the enzyme's action, which means they can prevent the enzyme from carrying out its catalytic function. This can be achieved through various mechanisms such as competitive or non-competitive inhibition. Additionally, cells can also control enzyme activity by restricting the production of enzymes. By regulating the synthesis of enzymes, cells can regulate the amount of active enzyme available in the cell, thereby controlling the overall enzyme activity.

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  • 42. 

    Some enzymes possess receptor sites, called ________________ _________________ , that are some distance away from the active site. Substances that bind to this area may inhibit or stimulate an enzyme's activity.

    Correct Answer
    allosteric sites, Allosteric Sites
    Explanation
    Enzymes have allosteric sites, which are receptor sites located away from the active site. These allosteric sites can be bound by substances that can either inhibit or stimulate the enzyme's activity.

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  • 43. 

    Allosterically controlled enzymes are usually composed of proteins in:

    • A.

      Primary structure

    • B.

      Secondary structure

    • C.

      Tertiary structure

    • D.

      Quaternary structure

    Correct Answer
    D. Quaternary structure
    Explanation
    Allosterically controlled enzymes are usually composed of proteins in the quaternary structure. This is because allosteric enzymes have multiple subunits that come together to form a functional enzyme. The quaternary structure refers to the arrangement of these subunits and the interactions between them. In allosteric enzymes, the binding of a molecule at one site can affect the activity of the enzyme at another site. This allosteric regulation is made possible by the complex structure and interactions within the quaternary structure of the enzyme.

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  • 44. 

    Allosterically controlled enzymes are usually composed of proteins in tertiary structure having several subunits, each with an active site. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    Allosterically controlled enzymes are usually composed of proteins in quaternary structure having several subunits, each with an active site.

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  • 45. 

    'A substance that binds to an allosteric site on an enzyme and stabilizes the protein conformation that keeps all the active sites available to their substrates.' This is the definition of which term?

    • A.

      Allosteric site

    • B.

      Activator

    • C.

      Allosteric inhibitor

    • D.

      None of the above

    Correct Answer
    B. Activator
    Explanation
    An activator is a substance that binds to an allosteric site on an enzyme and stabilizes the protein conformation that keeps all the active sites available to their substrates. This means that an activator enhances the activity of the enzyme by promoting the binding of substrates and increasing the rate of the enzymatic reaction.

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  • 46. 

    'A substance that binds to an allosteric site on an enzyme and stabilizes the inactive form of the enzyme.' This is the definition of which term?

    • A.

      Allosteric site

    • B.

      Activator

    • C.

      Allosteric inhibitor

    • D.

      None of the above

    Correct Answer
    C. Allosteric inhibitor
    Explanation
    An allosteric inhibitor is a substance that binds to an allosteric site on an enzyme and stabilizes the inactive form of the enzyme. This means that the inhibitor prevents the enzyme from functioning properly by keeping it in an inactive state. Therefore, the correct answer is allosteric inhibitor.

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  • 47. 

    What kind of inhibitors attach to the allosteric sites of certain enzymes?

    • A.

      Competitive inhibitors

    • B.

      Noncompetitive inhibitors

    • C.

      All of the above

    • D.

      None of the above

    Correct Answer
    B. Noncompetitive inhibitors
    Explanation
    Noncompetitive inhibitors are a type of inhibitor that attach to the allosteric sites of certain enzymes. Unlike competitive inhibitors, which bind to the active site and directly compete with the substrate, noncompetitive inhibitors bind to a different site on the enzyme, causing a conformational change that prevents the enzyme from functioning properly. This type of inhibition is not affected by substrate concentration and can't be overcome by increasing the substrate concentration. Therefore, the correct answer is noncompetitive inhibitors.

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  • 48. 

    The binding of an activator or inhibitor to one allosteric site will affect the activity of some of the active sites on the enzymes. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    The binding of an activator or inhibitor to one allosteric site will affect the activity of all the active sites on the enzymes.

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  • 49. 

    Allosteric regulators attach to their sites using strong bonds. True or false?

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    Allosteric regulators attach to their sites using weak bonds.

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  • 50. 

    Defined, feedback inhibition is:

    • A.

      A method of metabolic control in which a reactant formed later in a sequence of reactions allosterically inhibits an enzyme that catalyzes a reaction occuring earlier in the process

    • B.

      A method of metabolic control in which a product formed later in a sequence of reactions allosterically inhibits an enzyme that catalyzes a reaction occuring later in the process

    • C.

      A method of metabolic control in which a product formed later in a sequence of reactions allosterically inhibits an enzyme that catalyzes a reaction occuring earlier in the process

    • D.

      None of the above

    Correct Answer
    C. A method of metabolic control in which a product formed later in a sequence of reactions allosterically inhibits an enzyme that catalyzes a reaction occuring earlier in the process
    Explanation
    Feedback inhibition is a method of metabolic control in which a product formed later in a sequence of reactions allosterically inhibits an enzyme that catalyzes a reaction occurring earlier in the process. This mechanism helps regulate metabolic pathways by preventing the overproduction of certain molecules. When the concentration of the product exceeds a certain threshold, it binds to the enzyme and inhibits its activity, effectively slowing down the reaction and preventing the production of more product. This negative feedback loop helps maintain homeostasis and prevent the depletion of resources.

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  • Current Version
  • Mar 29, 2024
    Quiz Edited by
    ProProfs Editorial Team
  • Feb 21, 2010
    Quiz Created by
    Rflores314
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