Tag: surface chemistry

Quizzes (6) Questions (144)

Questions Related to surface chemistry

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

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

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

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

  1. critical

  2. supportive

  3. optimum

  4. none of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
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

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

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

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
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

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

Select the incorrect statement(s).

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The rate of enzyme catalysed reaction depends upon enzyme concentration.

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

Which of the following is true?

  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.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Enzymes are biological catalysts that speed up biochemical reactions occurring in living organisms. Most enzymes are proteinaceous in nature (though some are RNA ribozymes), and they are widely found in both plants and animals. Option C accurately describes their fundamental role as biocatalysts.

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

Enzyme activity is highest in the temperature range of:

  1. $0-15^o$C
  2. $15-25^o$C
  3. $25-45^o$C

  4. remain same in all
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Enzymes in the human body and most organisms function optimally within a moderate temperature range, typically 25-45 degrees Celsius, before denaturation occurs at higher temperatures.

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

Incorrect statement about a catalyst is?

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

How do enzymes increase the rate of reaction?

  1. By lowering activation energy

  2. By increasing activation energy

  3. By changing equilibrium constant

  4. By forming enzyme substrate complex
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

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

  1. saliva

  2. blood

  3. intestine

  4. adrenal gland
Reveal answer Fill a bubble to check yourself
A Correct answer
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.