Enzyme catalysis - class-XI

Adsorption theory of Heterogeneous catalysis involves five steps-

• Enzymes are macromolecular biological catalysts. Enzymes accelerate chemical reactions. The molecules upon which enzymes may act are called substrates and the enzyme converts the substrates into different molecules known as products. 

• Enzymes are macromolecular biological catalysts. Enzymes accelerate chemical reactions. The molecules upon which enzymes may act are called substrates and the enzyme converts the substrates into different molecules known as products. 

• Enzymes are macromolecular biological catalysts. Enzymes accelerate chemical reactions. The molecules upon which enzymes may act are called substrates and the enzyme converts the substrates into different molecules known as products. 

• Enzyme catalysis is unique in its efficiency and a high degree of specificity.
  

• Most highly efficient: One molecule of an enzyme may transform one million molecules of the reactant per minute.
  

• Highly specific nature: Each enzyme is specific for a given reaction, i.e., one catalyst cannot catalyse more than one reaction. 
  

• Highly active under optimum temperature: The rate of an enzyme reaction becomes maximum at a definite temperature, called the optimum temperature.
  

• Highly active under optimum pH: The rate of an enzyme-catalysed reaction is maximum at a particular pH called optimum pH, which is between pH values 5-7.
  

• Enzymes are normally homogeneous catalysts.

A substance produced by a living organism which acts as a catalyst to bring about a specific biochemical reaction.

Volume of N2 gas = 10^3 cm^3 = 1000 cm^3 at STP. Number of moles = 1000 / 22400 = 0.0446 mol. Number of molecules = 0.0446 * 6.022 * 10^23 = 2.686 * 10^22 molecules. Total surface area = (Number of molecules) * (Area per molecule) = 2.686 * 10^22 * 0.1602 * 10^-14 cm^2 = 4.303 * 10^7 cm^2 = 4303 m^2, which does not match any of the provided numerical options (579 m^2, 449 m^2, 579 cm^2), making none of these correct.

Enzymes in the living systems catalyse biological reactions. 

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.

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

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

The rate of enzyme catalysed reaction depends upon enzyme concentration.

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.

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.

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

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.

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).

The oxidation of sulfur dioxide to sulfur trioxide (2SO2 + O2 -> 2SO3) is a slow reaction that industrially requires a catalyst, specifically vanadium pentoxide (V2O5) or platinum, to proceed at a practical rate in the Contact process. In contrast, combustion reactions like sulfur or carbon burning in oxygen occur readily without a specialized catalyst.

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. Just as a key is used or a particular lock, each enzyme is used for specific reaction. 

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.

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.

Enzymes are highly specific in action.
Almost every biochemical reaction is controlled by its own specific enzymes.
Thus, the enzyme urease catalyzes the hydrolysis of urea. No other enzyme catalyzes this reaction.

A fundamental task of proteins is to act as enzymes catalysts that increase the rate of virtually all the chemical reactions within cells. Although RNAs are capable of catalyzing some reactions, most biological reactions are catalyzed by proteins. In the absence of enzymatic catalysis, most biochemical reactions are so slow that they would not occur under the mild conditions of temperature and pressure that are compatible with life. Enzymes accelerate the rates of such reactions by well over a million-fold, so reactions that would take years in the absence of catalysis can occur in fractions of seconds if catalyzed by the appropriate enzyme.

The maximum concentration of alcohol possible through a natural fermentation is about $12%$ ethanol,

Streptokinase is used to dissolve blood clots that have formed in the blood vessels. It is used immediately after symptoms of a heart attack occur to improve patient survival. This medicine may also be used to treat blood clots in the lungs (pulmonary embolism) and in the legs (deep venous thrombosis).

Ptyalin is the starch hydrolyzing enzyme secreted by salivary glands in human beings. It is also called as salivary amylase. Ptyalin secreted in the mouth brings about digestion of starch in the mouth itself.

True, Holoenzymes are complete and active enzymes.

Yes, Metals ion can active enzymes.

$Cl^{-}$ ions act as activators for amylase enzyme.

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.

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

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

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 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 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.

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

Enzymes are very specific in nature. Only those substrates that can fit into the active site of an enzyme can be bound within it. This specific action is similar to a lock and key where a key(reacting biochemicals) can only be used to actuate a specific lock(enzyme) and not all of them. 

A catalyst works by providing an alternative reaction pathway to the reaction product. The rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.