Tag: chemistry

Questions Related to chemistry

Which statement about enzymes is not correct?

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. Enzymes are in colloidal state.

  2. Enzymes are catalysts.

  3. Enzymes can catalyse any reaction.

  4. Urease is an enzymes.

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Correct Option: C
Explanation:

Enzymes are proteins and are giant molecules making them colloidal particles. They are shape selective and catalyzes a specific reaction in which they are suitable.  But they cannot catalyze any reaction.

Urease is an enzyme and catalyzes the hydrolysis of urea to ammonia and carbon dioxide.

Bacterial infection on eye surface is protected by the enzyme :

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. urease

  2. carbonic anhydrase

  3. lysozyme

  4. xymase

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Correct Option: C
Explanation:
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.
They decrease 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.

Urease is an enzyme that catalyzes the hydrolysis of urea forming ammonia and carbon dioxide.
Conjunctiva (membrane covering the eye) is protected by lysozyme and defensin enzymes. However, when these protective barriers fall, conjunctivitis results.

Identify the correct statement regarding enzymes.

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. Enzymes are specific biological catalyst that possess well defined active state.

  2. Enzymes are normally heterogeneous catalyst that are very specific in their action.

  3. Enzymes are specific biological that cannot be poisoned.

  4. Enzymes are specific biological catalyst that can normally function at very high temperature $ ( T \simeq 1000 K).$

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Correct Option: A
Explanation:
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.
They decrease 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.

Enzymes in the human body function as a catalyst.

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. True

  2. False

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Correct Option: A
Explanation:

Catalysts increase the rate of a reaction by providing an intermediate to be formed, although the catalyst is left unchanged at the end of the reaction. Catalysts speed up reactions, and without them these reactions might be too slow to sustain life processes.

An enzyme is a protein which has a highly specific amino acid sequence as well as 3D structure allowing it to catalyse reactions. In this sense, they are biological catalysts.

Examples of enzymes are DNA Polymerases (which replicate our DNA to allow our cells to divide) and Kinases (which add phosphate groups to other proteins that might be part of a signalling pathway).

Which requires catalyst

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. $S+O _2 \rightarrow SO _2$

  2. $2SO _2+O _2 \rightarrow 2SO _3$

  3. $C+O _2 \rightarrow CO _2$

  4. All

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Correct Option: A

Catalyst makes the reaction more exothermic.

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. True

  2. False

  3. Ambiguous

  4. Data insufficient

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Correct Option: B
Explanation:

The statement is false.
Catalyst does not makes the reaction more exothermic.
A catalyst can lower the activation energy required for the reaction to take place and allows the reaction to reach equilibrium faster, but as the catalyst is unchanged at the end of the reaction, the total energy absorbed or released during the reaction will be the same.

Enzyme catalysed reactions are highly specific.
chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. True

  2. False

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Correct Option: A
Explanation:

Enzyme catalysed reactions are highly specific. Just as a key is used or a particular lock, each enzyme is used for specific reaction. 

Transition metals are more efficient catalyst.

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. True

  2. False

  3. Ambiguous

  4. Data insufficient

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Correct Option: A
Explanation:

Transition metals are more efficient catalyst as they have vacant d- orbitals. The ability of transition metals to form more than one stable oxidation state means that they can accept and lose electrons easily. This enables them to catalyze certain redox reactions. They can be readily oxidized and reduced again, or reduced and then oxidized again, as a consequence of having a number of different oxidation states of similar stability. They can behave either as homogeneous catalysts or as heterogeneous catalysts.

Zymase is used to catalyse the hydrolysis of glucose.
chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. True

  2. False

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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 catalyses the hydrolysis of urea, forming ammonia and carbon dioxide.
Zymase is used to catalyse the hydrolysis of glucose.
Zymase is an enzyme complex that catalyses the fermentation of glucose into ethanol and carbon dioxide. It occurs naturally in yeasts.

Enzymes also act as a catalyst in biological process.
chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. True

  2. False

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Correct Option: A
Explanation:

Enzymes also act as catalyst in biological process. Enzymes are biological molecules that act as catalysts and help complex reactions to proceed faster without altering the rate of reaction.