Tag: chemistry

Questions Related to chemistry

The efficiency of an enzyme to catalyse a reaction is due to its capacity to:

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. Reduce the activation energy of the reaction

  2. Form strong enzyme-substrate complex

  3. Decrease the bond energies of all substrate molecules

  4. Alter the substrate geometry to fit into the shape of the enzyme molecule

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Correct Option: A
Explanation:

Enzymes are catalysts for biological reactions. Catalysts have the ability to lower the activation energy barrier of the reaction. The more it reduces the activation energy barrier the more efficient it will be.

Hence, option A is correct.

The temperature at which the enzyme shows maximum activity is known as _____________ temperature.

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. critical

  2. supportive

  3. optimum

  4. none of the above

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Correct Option: C
Explanation:

Each enzyme has a temperature range in which a maximal rate of reaction is achieved. This maximum is known as the optimum temperature of the enzyme. The optimum temperature of each enzyme is different

The effectiveness of a catalyst is minimum at its optimum temperature.

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

A catalyzed reaction rate is much faster at the optimum temperature of an enzyme. This is a result of increased catalyst activity due to its maximum effectiveness at the optimum temperature

Select the incorrect statement(s).

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. Enzyme catalysed reactions are usually hydrolytic in nature

  2. Enzyme catalysed reactions takes place with evolutions of gases

  3. The rate of reaction does not depend upon enzyme concentration

  4. Enzymes are colloidal in nature

Show answer
Correct Option: C
Explanation:

The rate of enzyme catalysed reaction depends upon enzyme concentration.

Which of the following is true?

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. Enzymes are non - proteinaceous nitrogen containing compounds.

  2. Amylase convert starch into amylose.

  3. Biocatalysts, catalyse the reaction occurring in living beings.

  4. Enzymes are not found in plants.

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Correct Option: A

Enzyme activity is highest in the temperature range of:

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. $0-15^o$C

  2. $15-25^o$C

  3. $25-45^o$C

  4. remain same in all

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Correct Option: C

In conversion of sucrose to glucose, the enzyme is: 

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. zymase

  2. lipase

  3. invertase

  4. diastase

Show answer
Correct Option: C
Explanation:

The Enzyme Invertase is used for the conversion of Sucrose to Glucose.

It helps in dissociation of sucrose to glucose and fructose.

Incorrect statement about a catalyst is?

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. It does not alter Gibbs energy, $\Delta G$ of a reaction

  2. it catalyses both spontaneous and non-spontaneous reactions

  3. A small amount of catalyst can catalyse a large amount of reaction

  4. It does not affect equilibrium constant of a reaction

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Correct Option: A

How do enzymes increase the rate of reaction?

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. By lowering activation energy

  2. By increasing activation energy

  3. By changing equilibrium constant

  4. By forming enzyme substrate complex

Show answer
Correct Option: A
Explanation:
A Catalyst is a substance which acclerates the rate of a chemical reaction without undergoing any change in its chemical composition or massduring the reaction. A catalyst acclerates the rate of a reaction by lowering the activation energy.
Enzyme Catalysis - These are catalysts in the living system. Enzymes are substances which by their their presence, alter the rate of anybiological event. These are mainly proteins, and enzyme action is structure specific.

Enzyme catalysis is the increase in the rate of a chemical reaction by the active site of a protein. The protein catalyst (enzyme) may be part of a multi-subunit complex, and/or may transiently or permanently associate with a Cofactor (e.g. adenosine triphosphate). Catalysis of biochemical reactions in the cell is vital due to the very low reaction rates of the uncatalysed reactions. A key driver of protein evolution is the optimization of such catalytic activities via protein dynamics.


Enzymes are macromolecular biological catalysts. These are highly selective catalysts greatly accelerating both the rate and specificity of metabolic reactions. All enzymes are insoluble since they exist in the colloidal state. Urease is an enzyme that catalyzes the hydrolysis of urea, forming ammonia and carbon dioxide.
They decrease activation energy by providing alternate pathway for process and hence, increase the rate of reaction.

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 gland

Show answer
Correct Option: A
Explanation:
Enzymes are macromolecular biological catalysts. These are highly selective catalysts greatly accelerating both the rate and specificity of metabolic reactions. All enzymes are insoluble since they exist in the colloidal state. Urease is an enzyme that catalyzes the hydrolysis of urea, forming ammonia and carbon dioxide.
They decrease the activation energy by providing alternate pathway (enzyme reacts with the substrate to form an intermediate ES complex, which would be impossible in the absence of the enzyme) for the process.
Enzyme + Substrate → Complex → Product + Enzyme
Saliva is a watery substance located in the mouths of animals, secreted by the salivary glands. Human saliva is $99.5\%$ water, while the other $0.5\%$ consists of electrolytes, mucus, glycoproteins, enzymes and antibacterial compounds.
Digestive functions of saliva include moistening food and helping to create a food bolus. This lubricative function of saliva allows the food bolus to be passed easily from the mouth into the esophagus. Saliva contains the enzyme amylase, also called ptyalin, which is capable of breaking down starch into simpler sugars such as maltose and dextrin that can be further broken down in the small intestine. Only about $30\%$ starch digestion takes place in the mouth cavity.