Tag: proteins and enzymes

Questions Related to proteins and enzymes

The temperature at which the catalytic activity of the catalyst is maximum, is called: 

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. critical temperature

  2. room temperature

  3. absolute temperature

  4. optimum temperature

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Correct Option: D
Explanation:

Some catalysts are, however, physically altered by a rise in temperature and hence their catalytic activity may be decreased. This is particularly true with colloidal solutions like that of platinum, since a rise in the temperature may cause their coagulation. In such a case, the rate of reaction increases up to a certain point and then gradually decreases. The rate of reaction is maximum at a particular temperature; that is Optimum temperature.

Which one of the following statements is false?

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. Enzymes arc highly specific

  2. Enzymes increase activation energy

  3. Enzymes require optimum temperature

  4. None of the above

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Correct Option: A,C
Explanation:
  • Enzymes serve as a biological catalyst by accelerating the rate of chemical reaction occurring inside the cells of living organisms, thus decreasing the activation energy required for the reaction to occur. 
  • Enzymes are very specific in nature, implying that, a particular enzyme can catalyze only a specific reaction and not all the reactions. 
  • The optimum temperature for an enzyme to function effectively is $37.5^o C$ which is also the normal human body temperature. At a temperature above this, enzymes undergo denaturation, thus, showing a reduced performance

Which of the following catalysts is sensitive to temperature changes?

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. Enzymes

  2. $Pt, Fe$

  3. $Ni, Fe$

  4. All of the above

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Correct Option: A
Explanation:

Enzymes are specific in their action and catalyze reactions at lower temperature. At high temperature, they lose their specific nature and get denatured.

The function of zymase is to: 

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. change starch into sugar

  2. ferment glucose to alcohol and carbon dioxide

  3. change malt sugar into glucose

  4. change starch into malt sugar and dextrin

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Correct Option: B
Explanation:

Zymase is an enzyme complex that catalyzes the fermentation of sugar into ethanol and carbon dioxide.
Hence option B is correct.

The enzyme ptyalin used for digestion of food is present in: 

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. saliva

  2. blood

  3. intestine

  4. adrenal glands

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Correct Option: A
Explanation:

The enzyme ptyalin, also known as amylase is present in saliva and is responsible for breaking down starch into simple sugars such as dextrin and maltose which are further broken down in the intestine

The function of enzymes in the living system is to________.

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. Transport oxygen

  2. Provide immunity

  3. Catalyse biochemical reaction

  4. Provide energy

Show answer
Correct Option: C
Explanation:

The function of enzymes in the living system is to catalyse biochemical reaction.
Enzymes are highly substrate specific and catalyze reactions by providing an alternate pathway of lower activation energy.

A catalyst increases the rate of reaction by_________.

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. Decreasing enthalpy

  2. Decreasing internal energy

  3. Decreasing activation energy

  4. Increasing activation energy

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Correct Option: C
Explanation:

A catalyst increases the rate of reaction by decreasing activation energy.
Note: The function of enzymes in the living system is to catalyse biochemical reaction.
Enzymes are highly substrate specific and catalyze reactions by providing an alternate pathway of lower activation energy.

 Identify the correct statement regarding enzymes:

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. Enzymes are specific biological catalysts that can normally function at very high temperature

  2. Enzymes are normally heterogeneous catalysts that are very specific in action.

  3. Enzymes are specific biological catalysts that cannot be poisoned

  4. Enzymes are specific biological catalysts that possess well defined active site

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Correct Option: D
Explanation:

Enzymes are specific biological catalysts that possess well defined active site.
Enzymes function at physiological temperature $ \displaystyle \simeq (37 : ^oC)$


Enzymes can be poisoned using suitable inhibitors.

Hence, the correct option is $\text{D}$

Select the correct statements about enzymes.
chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. Enzymes arc biological catalysts found in organisms

  2. All enzymes are proteins

  3. Enzymes can catalyse any reaction

  4. Enzymes activity is optimum at $37^o C $

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Correct Option: A,D

Which of the following statements regarding enzyme inhibition is correct -

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. Competitive inhibition is seen when a substrate competes with an enzyme for
    binding to an inhibitor protein

  2. Non-competitive inhibitors often bind to the
    enzyme irreversibly

  3. Competitive inhibition is seen when the substrate and the inhibitor compete for the active site on the enzyme

  4. Non-competitive inhibition of an enzyme can be overcome by adding large amount of substrate

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Correct Option: C
Explanation:
Competitive inhibition is seen when the substrate and the inhibitor compete for the active site on the enzyme because competitive inhibitor has a similar structure as that of a substrate, so it blocks the active site of an enzyme thereby reducing the production formation.