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Classification of enzyme - class-XI

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Which of the following is not a co-enzyme?

  1. NAD

  2. NADP

  3. FAD

  4. ATP


Correct Option: D
Explanation:

ATP or adenosine triphosphate is a nucleotide. It is not a co-enzyme.

Select the type of enzyme involved in the above reaction.

$\boxed{S - G + S' \rightarrow S + S' - G}$

  1. Dehydrogenase

  2. Transferase

  3. Hydrolase

  4. Lyase

  5. Isomerase


Correct Option: B
Explanation:

Transferases are the enzymes that catalyze group transfer reactions. In the figure, one group G has been transferred to another group S'. It is a classical example of a group transfer reaction.

Who proposed the principle of "Induced fit"?

  1. Jacob

  2. Fischer

  3. Koshland

  4. Laderberg


Correct Option: C
Explanation:

The induced-fit model is proposed by Daniel Koshland in 1958. It is the most accepted model for enzyme-substrate complex. It describes the formation of the Enzyme substrate as a result of the interaction between the substrate and a flexible active site which means exposure of an enzyme to a substrate causes the active site of the enzyme to change shape in order to allow the enzyme and substrate to bind. Hence option C is correct.

NADP is

  1. A coenzyme

  2. A part of tRNA

  3. An enzyme

  4. A part of rRNA


Correct Option: A
Explanation:

Coenzymes are organic cofactors which are required for enzymatic action of certain enzymes. NADP is a coenzyme form of vitamin nicotinamide or niacin.

DNA polymerase enzyme is responsible for the synthesis of

  1. DNA from RNA

  2. DNA from DNA

  3. RNA from DNA

  4. RNA from RNA


Correct Option: B
Explanation:

DNA polymerase is an enzyme used in DNA replication. It synthesizes DNA on a DNA template. Bacteria have three different DNA polymerases, i.e., DNA pol I, DNA pol II and DNA pol III; while eukaryotes have several DNA polymerase enzymes.

Which of the following enzyme can form RNA from DNA?

  1. Restriction enzyme

  2. DNA polymerase

  3. RNA polymerase

  4. Reverse transcriptase


Correct Option: C
Explanation:

RNA polymerase participates in RNA synthesis during transcription process. It synthesizes RNA on DNA template.

Basically how many types of enzymes have been recognised by International Union of Biochemistry?

  1. 4

  2. 5

  3. 6

  4. 8


Correct Option: C
Explanation:

According to the modern classification system given by International Union of Biochemistry, enzymes have been classified into six classes as follows :
Class First is Oxidoreductase.
Class Second is Transferase.
Class Third is Hydrolase.
Class Fourth is Lyase.
Class Fifth is Isomerase.
Class Sixth is Ligase.

Esterase enzyme belongs to which of the following class?

  1. Oxidoreductase

  2. Carboxylase

  3. Hydrolases

  4. Transferases


Correct Option: C
Explanation:

Esterases are the enzyme which hydrolyse ester linkage. Hence, esterases belong to class Hydrolase. Hydrolases are the enzymes catalysing hydrolysis.

Enzymes concerned with transfer of electrons are

  1. Hydrolase

  2. Dehydrogenase

  3. Transaminase

  4. Deoxygenase


Correct Option: B
Explanation:

Dehydrogenases catalyze dehydrogenation reactions, which involve addition or removal of electrons. Addition or removal of electrons will lead to reduction or oxidation of substrates. Dehydrogenases are a type of oxidoreductases.

Which one of the following pair is wrongly matched?

  1. Detergents - lipase

  2. Alcohol - nitrogenase

  3. Fruit juice - pectinase

  4. Textile - amylase


Correct Option: B
Explanation:

This question relates to the industrial applications of enzymes. Alcohol is not produced by the use of nitrogenase. Nitrogenase performs complex functions of nitrogen fixation by bacteria. Alcohol is produced by the fermentation process of sugars carried out by Yeast.

Which one is not an example for hydrolases?

  1. Dehydrogenase

  2. Protease

  3. Amylase

  4. Esterase

  5. Sucrase


Correct Option: A
Explanation:

Dehydrogenases catalyze dehydrogenation reactions which involve addition or removal of electrons. The addition or removal of electrons will lead to reduction or oxidation of substrates. Dehydrogenases are a type of oxidoreductases. Some of the important hydrolases includes amylases, sucrase, lactase, maltase, protease, esterase etc.

Most of the biochemical reactions differ from those occurring in the non-living world in ________________.

  1. Requiring energy

  2. Releasing energy

  3. Being enzymatic

  4. Being spontaneous


Correct Option: C

Lactic dehydrogenase (LDH) which catalyzes pyruvate to lactate is an example of

  1. Apoenzyme

  2. Antienzyme

  3. Isoenzyme

  4. Coenzyme


Correct Option: C
Explanation:

Some enzymes have several molecular forms, example: 16 for $\alpha$-amylase and 5 for lactate dehydrogenase (LDH). They are called as isoenzymes or isozymes. They differ in substrate affinity, maximum activity and regulatory properties.

IUBMB has divided enzymes into classes

  1. 4

  2. 5

  3. 6

  4. 7


Correct Option: C
Explanation:

The International Union of Biochemistry and Molecular Biology (IUBMB) divided enzymes into 6 classes. 

1) Oxidoreductases
2)Transferase
3)Hydrolases
4)Lyases
5)Isomerases
6)Ligases
Thus, the answer is C.

Enzymes which act similarly are called as

  1. Isoenzyme

  2. Cofactor

  3. Coenzymes

  4. All of the above


Correct Option: A
Explanation:

Isoenzymes are enzymes that catalyze identical chemical reactions but are composed of different amino acid sequences. They are sometimes referred to as isozymes. Isoenzymes are produced by different genes. They occur in many tissues throughout the body and are important for different developmental and metabolic processes. Alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) are examples of isoenzymes.

Hexokinase (Glucose $+$ ATP $\longrightarrow$ Glucose 6-P $+$ ADP) belongs to the category

  1. Transferases

  2. Lysases

  3. Oxidoreductases

  4. Isomerases


Correct Option: A
Explanation:

Transferase is an enzyme which transfers a group from one molecule to another molecule. Hexokinase is the enzyme which transfers one phosphate from ATP to glucose and forms glucose 6-phosphate.

(Glucose ++ ATP  Glucose 6-P ++ ADP)
Thus, the correct answer is A.

Enzymes functional in cells are called

  1. Endoenzymes

  2. Exoenzymes

  3. Apoenzymes

  4. Isoenzymes


Correct Option: A
Explanation:

Endoenzyme is the cells which function inside the cell. It is also known as intracellular enzymes. It helps in the catalysis of the intracellular metabolic reaction. 

Exoenzymes are the enzymes which function outside the cell.
Isoenzyme is also known as isozyme. When the two enzymes differ in amino acid sequence but catalyze the same chemical reaction they are known as isoenzyme. They are two different molecular form of the enzyme.
Enzymes are proteins which help to catalyze the biochemical reaction. The enzyme has a protein part which is not active is known as apoenzyme.
So, the correct answer is option A.

Which enzyme is concerned with transfer of electrons?

  1. Desmolase

  2. Hydrolase

  3. Dehydrogenase

  4. Transaminase


Correct Option: A
Explanation:
Desmolase catalyzes the formation or destruction of carbon-carbon bonds within a molecule. It is involved in the transfer of electrons.
Hydrolase is the enzyme which catalyzes the splitting of compounds by addition of water.
Dehydrogenase is an enzyme which participates in the oxidoreductase reaction by using an electron acceptor.
Transaminase catalyzes aminotransferase reaction between an amino acid and a α-keto acid.
So, the correct answer is option B.

Enzyme amylase belongs to class 

  1. Transferases

  2. Hydrolases

  3. Isomerases

  4. Oxidoreductases


Correct Option: B
Explanation:

Hydrolases are the enzymes which break large molecules into smaller ones with the help of hydrogen and hydroxyl groups of water molecules, this phenomenon is known as hydrolysis. Amylase is the enzyme produced by the salivary gland and is found in saliva. It breaks starch into glucose. Thus, the correct answer is B.

Ribozyme is

  1. RNA with enzyme activity

  2. RNA without sugar

  3. RNA without phosphate

  4. RNA with extra phosphate


Correct Option: A
Explanation:

Ribozymes are also known as ribonucleic acid enzymes. These are RNA molecules which helps in the catalysis of a particular reaction. It was discovered in the year 1982. The RNA can act as both genetic material and can act as a biocatalyst. It acts as a part of ribosome which attaches to the amino acid during protein synthesis. It increases the rate and specificity of peptide bond synthesis and phosphodiester bond. So, the correct answer is option A.

Nickel is component of

  1. PEP carboxylase

  2. Rubisco

  3. Urease

  4. Nitrate reductase


Correct Option: C
Explanation:

Urease is a nickel-containing metalloprotein which catalyzes the hydrolysis of urea into carbon dioxide and ammonia. Due to the production of ammonia, it increases the production of ammonia. Sumner crystallized an enzyme known as urease and reported that all enzymes are protein. Heliobacter pylori are microbial ureases found in the stomach.

So, the correct answer is option C.

Which is false about prosthetic groups?

  1. Proteins

  2. Non-proteins

  3. Metal compounds

  4. Tightly bound to enzymes


Correct Option: A
Explanation:

Many enzymes show enzymatic activity only in association with certain non protein substances. Such substances are known as cofactors. Cofactors may be simple ions such as magnesium or potassium ions or complex organic compounds. An organic non-protein cofactor which is easily separable from the enzyme is called coenzyme and the non-protein organic cofactor which is tightly bound to and non-dissociable from the enzyme is termed as prosthetic group. The organic cofactors directly reduce the activation energy and thus form a functional part of active site of enzyme. They act as carriers of chemical groups, atoms or electrons removed from the substrates during reactions.

Thus, the correct answer is option A.  

Enzymes with heme as prosthetic group are 
(a) Catalase
(b) Carboxypeptidase
(c) Succinic dehydrogenase
(d) Peroxidase

  1. a and d

  2. a ony

  3. a and b

  4. b and c

  5. c and a


Correct Option: A
Explanation:

Certain enzymes are made up of two parts - a protein part of enzyme called apoenzyme and a non-protein part called cofactor. Such enzymes are called conjugated enzymes. The working combination of apoenzyme and cofactor together form the holoenzyme. Organic cofactors are of two types- coenzymes and prosthetic groups. Coenzymes are easily separable organic cofactors while prosthetic groups are non-protein organic cofactors firmly associated with protein part of enzyme called apoenzyme. Heme is iron containing prosthetic group in hemoglobin, myoglobin, cytochrome, catalase and peroxidase. Catalase and peroxidase cause the breakdown of hydrogen peroxide to oxygen and water. Carboxypeptidase requires zinc for its activity.

Thus, the correct answer is option A.  

Match and find the correct option.

$(a)$ Oxidoreductases $(i)$ Linking of the compounds
$(b)$ Isomerases $(ii)$ Removal of group from substrate
$(c)$ Ligases $(iii)$ Interconversion of isomers
$(d)$ Lyases $(iv)$ Dehydrogenases
$(v)$ Hydrolysis
  1. $a - iv, b - i, c - iii, d - ii$

  2. $a - iv, b - iii, c - i, d - ii$

  3. $a - iii, b - iv, c - ii, d - v$

  4. $a - ii, b - v, c - iii, d - i$


Correct Option: B
Explanation:
Oxidoreductase is a dehydrogenase which acts as an acceptor of hydrogen or electrons. 
Isomerases are class of enzymes that convert a molecule from one isomer to another isomer. 
Ligase is an enzyme that can catalyze the joining of two large molecules by forming a new chemical bond between them. 
An enzyme that forms double bonds by removing groups from a substrate other than by hydrolysis, is called lyases.
So the correct answer is B. 

A simple enzyme is

  1. Succinate dehydrogenase

  2. Urease

  3. Transaminase

  4. Ribozyme


Correct Option: A
Explanation:
Succinate dehydrogenase is a enzyme which is present in the inner mitochondrial membrane. It plays an important role in citric acid cycle and the electron transport chain.
It catalyzes the oxidation of succinate to fumarate. It is a conjugated protein as it has flavo protein which has FMN or FAD molecule as a prosthetic group.
So, the correct answer is option A.

Ribozyme was discovered by

  1. Kuhne

  2. Duclaux

  3. Cech et al

  4. Altman et al


Correct Option: A
Explanation:

Ribozymes are also known as ribonucleic acid enzymes. These are RNA molecules which helps in the catalysis of a particular reaction. It was discovered in the year 1982. The RNA can act as both genetic material and can act as a biocatalyst. It acts as a part of ribosome which attaches to the amino acid during protein synthesis. Thomas R. Cech and Sidney Altman discovered catalytic properties of RNA. So, the correct answer is option D.

Hydrolytic enzymes which act on low pH are called as : -

  1. Protease

  2. -Amylase

  3. Hydrolases

  4. Peroxidase


Correct Option: C
Explanation:
The stomach has low pH due to the secretion of HCl. Protease, an enzyme for digesting protein acts in low pH i.e. in the stomach. Amylase is a starch (carbohydrate) digesting enzyme and carbohydrate digestion does not occur in the stomach. All digestive enzymes are hydrolases. Peroxidase is an iron-containing enzyme, found mainly in plants but also present in leucocytes and milk, that catalyses the dehydrogenation (oxidation) of various substances in the presence of hydrogen peroxide.

So, the correct answer is 'Hydrolases'.

Coenzymes NAD and NADP contain the vitamins

  1. Niacin

  2. Biotin

  3. Thiamine

  4. Vitamin ${B} _{12}$


Correct Option: A
Explanation:
Nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) are derivatives of the B-vitamin i.e., niacin. They act as coenzymes in hundreds of redox reactions.

Enzyme urease, first crystallised by Sumner was obtained from

  1. Human urine

  2. Canavalia

  3. Pancratium

  4. Thalictrum


Correct Option: A
Explanation:
Sumner crystallized an enzyme known as urease from human urine and reported that all enzymes are protein. It catalyzes the hydrolysis of urea into carbon dioxide and ammonia. John Howard Northrop and Wendell Meredith Stanley shared the noble prize with Sumner for their work on the enzyme.
Buchner in 1897, prepared a yeast extract and added sugar solution to it and observed the process of fermentation. 
So, the correct answer is option A.

Match and find the correct option.

           $I$             $II$
$(a)$ Transferases $(i)$ Epimerase
$(b)$ Hydrolases $(ii)$ Kinases
$(c)$ Lyases $(iii)$ Phosphatase
$(d)$ Isomerase $(iv)$ Fumarase
  1. $a - ii, b - iii, c - iv, d - i$

  2. $a - ii, b - iii, c - i, d - iv$

  3. $a - ii, b - i, c - iii, d - iv$

  4. $a - ii, b - iv, c - iii, d - i$


Correct Option: A
Explanation:
A kinase is an enzyme that catalyzes the transfer of phosphate groups.  It belongs to the family of transferase. 
Phosphatase enzyme catalyzes the hydrolysis of its substrate,  it is a subcategory of hydrolases. 
Fumarase enzyme belongs to the family of lyases,  specifically hydro lyases, which cleave carbon-oxygen bonds. 
Epimerases are isomerase enzymes that catalyze the inversion of compounds. So the correct answer is A. 

Which of the following is not corretly matched for the organism and its cell wall degrading enzyme ?

  1. Bacteria - Lysozyme

  2. Plant cells - Cellulase

  3. Algae - Methylase

  4. Fungi - Chitinase


Correct Option: C
Explanation:
In algae, the cell wall is made up of cellulose degraded by cellulase enzyme. Bacteria have lysozyme, plants cells have cell wall degraded by cellulose and fungi have chitinase.

So, the correct answer is 'Algae - Methylase'.

Which class of enzyme catalyzes following reaction?
$\overset { X }{ \underset { C }{ | }  } \overset { Y }{ \underset { C\longrightarrow \quad X-Y+C=C }{ | }  } $

  1. Hydrolases

  2. Lyases

  3. Ligases

  4. Isomerases


Correct Option: A
Explanation:

Hydrolases are biological enzymes that catalyze the hydrolysis of a chemical reaction. They usually divide larger molecules into two smaller molecules. It is a class containing more than 200 enzymes. Some common hydrolases are esterases, proteases, lipases etc.

So, the correct option is 'Hydrolases'.

An enzyme which brings about conversion of starch into maltose is:

  1. catalase

  2. maltase

  3. invertase

  4. diastase


Correct Option: A

The formation of peptide bonds is catalysed by the enzyme ________.

  1. Peptidyl transferase

  2. Endonuclease

  3. DNA ligase

  4. DNA Polymerase


Correct Option: A

Choose the type of enzyme involved in the following reaction.


$S - G + S' \longrightarrow S + S' - G$

  1. Dehydrogenase

  2. Transferase

  3. Hydrolase

  4. Lyase

  5. Isomerase


Correct Option: B
Explanation:

Based on the type of reaction catalyzed, the international union of biochemist have classified enzymes into six major classes- Oxidoreductase, Transferase, Hydrolase, Lyase, Ligase and Isomerase.
Transferase is the general name for the class of enzymes that enact the transfer of specific functional groups (e.g. a methyl or glycosyl group) from one molecule (called the donor) to another (called the acceptor).

In which one of the following enzymes, is copper necessarily associated as an activator? 

  1. Carbonic anhydrase

  2. Tryptophanase

  3. Lactic dehydrogenase

  4. Tyrosinase


Correct Option: D
Explanation:

Tyrosinase is a copper-containing enzyme present in plant and animal tissues that catalyzes the production of melanin and other pigments from tyrosine by oxidation, as in the blackening of a peeled or sliced potato exposed to air. In animals it is found inside melanosomes which are synthesised in the skin melanocytes.

The cytochromes are 

  1. Peroxidase

  2. Iron protoporphyrin

  3. Pyridine nucleotides

  4. Metal containing flavoproteins


Correct Option: B
Explanation:

Cytochromes are iron-porphyrin or heme proteins discovered by MacCunn. Cytochromes are bound to inner mitochondrial membrane and are primarily responsible for the generation of ATP via mitochondrial electron transport system. Whereas all other cytochromes have iron only, the cytochrome a possesses both iron and copper. With iron it picks up electrons and through copper it hands over electrons to oxygen.

Which of the following is main enzyme of plasma membrane?

  1. TPPase

  2. ATPase

  3. Peptidyl transferase

  4. Catalases


Correct Option: B
Explanation:

ATPase are a class of enzymes that catalyze the dephosphorylation of ATP into ADP and a free phosphate ion. This dephosphorylation reaction releases energy, which the enzyme harnesses to drive other chemical reactions that would not otherwise occur. This process is widely used in all known forms of life. Such enzymes are integral membrane proteins anchored within biological membranes (plasma membrane), and move solutes across the membrane, typically against their concentration gradient.

An enzyme which catalyses the conversion of aldose sugar to ketose would be classified as

  1. Transferases

  2. Isomerases

  3. Hydrolases

  4. Ligases


Correct Option: B
Explanation:

Isomerases are the enzymes which catalyse transfer of groups within molecules to yield isomeric bonds. As aldose and ketose sugars are isomers, their interconversion is catalyzed by isomerases.

Transferases will catalyze group transfer reactions. 
Hydrolases will catalyze hydrolytic reactions and ligases catalyze formation of C-C, C-S, C-O and C-N bonds by condensation reactions coupled to ATP cleavage.

Which one of them catalyzes oxidation-reduction reactions?

  1. Oxidase

  2. Oxidoreductase

  3. Oxygenase

  4. All of the above


Correct Option: D
Explanation:

Certain enzymes carry oxidation reduction reactions. Oxidation is defined as the chemical process which involves loss of electron whereas reduction is the process in which a substrate accepts electron.
An oxygenase is any enzyme that oxidizes a substrate by transferring the oxygen from molecular oxygen O$ _2$ (as in air) to it.

An oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule, the reductant, also called the electron donor, to another, the oxidant, also called the electron acceptor.
An oxidase is any enzyme that catalyzes an oxidation-reduction reaction, especially one involving molecular oxygen (O$ _2$) as the electron acceptor.

J.B. Sumner isolated first enzyme from jack beans as

  1. Amylase

  2. Trypsin

  3. Urease

  4. Renin


Correct Option: C
Explanation:

J.B. Sumner isolated ureases from the jack beans and proved enzymes to be proteins, that could be isolated in crystalline form.

Peptidyl transferase enzyme found on 

  1. Cytoplasm

  2. E.R

  3. Golgi body

  4. Ribosomes


Correct Option: D
Explanation:

The peptidyl transferase is an aminoacyltransferase, it performs the primary enzymatic function of the ribosome, which forms peptide bonds between adjacent amino acids using tRNAs during the translation process of protein biosynthesis. Peptidyl transferase activity is carried out by the ribosome. Peptidyl transferase activity is not mediated by any ribosomal proteins but by ribosomal RNA (rRNA), a ribozyme. 

Carbonic anhydrase is the best known example of 

  1. Hydrolase

  2. Transferase

  3. Lyase

  4. Coagulative


Correct Option: C
Explanation:

Lyase are the enzymes which catalyze breakdown reactions without hydrolysis. Lyases are classified as EC 4 in the EC number classification of enzymes. Lyases can be further classified into several subclasses : EC 4.1 includes lyases that cleave carbon-carbon bonds, such as decarboxylases (EC 4.1.1), aldehyde lyases (EC 4.1.2), oxo acid lyases (EC 4.1.3) and others (EC 4.1.99).

The fastest acting enzyme, in the biological kingdom, is 

  1. Lipase

  2. Amylase

  3. Peptidase

  4. Carbonic anhydrase


Correct Option: D
Explanation:

Enzymes are biological catalysts which catalyze biological reactions. They do not modify the chemical equilibria in any manner but simply make the attainment of equilibrium faster. Carbonic anhydrase catalyzes reversible reaction between carbon dioxide and water to form carbonic acid. This enzyme is one of the fastest enzyme. It is especially abundant in human erythrocytes.

First discovered enzyme was

  1. Isomerase

  2. Transaminase

  3. Zymase

  4. Transferase


Correct Option: C
Explanation:

Enzymes are biological catalysts, which activate various biochemical reactions of a living cell in a highly specific and precise manner. Enzymology is the study of enzymes. The name enzyme was coined by Kuhne in 1878. Pasteur recognised that some microorganisms like yeasts have got a capacity to cause fermentation in wine. In 1897, Buchner discovered that yeast extract could bring about fermentation of grape juice, like the living yeast cells. He also observed that the extract has lost its catalytic activity on boiling. He coined the word zymase for the active principle involved in the fermentation. The substance on which the enzyme acts is called substrate. Enzymes are essentially proteins but all proteins are not enzymes.

Enzymes, vitamins and hormones can be classified into a single category of biological chemicals, because all of these

  1. Are exclusively synthesized in the body of a living organism as at present.

  2. Enhance oxidative metabolism.

  3. Are conjugated proteins.

  4. Help in regulating metabolism.


Correct Option: D
Explanation:
There are more than thousand of biomolecules involve in living organisms in various biological processes. Some are vitamins, hormones, enzymes, ATP, carbohydrates, lipids, nucleic acids and proteins. Out of these main carbohydrates, proteins, lipids and nucleic acid are main biomolecules which play a vital role in living systems and mainly responsible for almost all biochemical processes. The biological molecules or biomolecules are involved in metabolic activities of living bodies such as plants and animals. Most of the biomolecules in the living cell have some broad functions like:
1. They are essential to cellular and body structure.
2. They act as energy-rich fuels during cellular respiration.
3. The molecules are used to carry information of controlling growth and biological characteristics from one generation to another.
4. They are good catalytic agents for the various chemical processes occur in cell and living body.

Ribozymes are 

  1. RNA acting as enzymes.

  2. Antibody acting as enzymes.

  3. Ribosomes acting as enzymes.

  4. None of the above.


Correct Option: A
Explanation:

Enzymes are biological catalysts which speed up the biological reactions. All metabolic reactions in a cell are catalyzed by enzymes. Almost all enzymes are proteins. There are some nucleic acids that behave like enzymes. These are called ribozymes. Ribozymes are molecules of ribonucleic acid with catalytic activity.

Which one of the following hydrolyze internal phosphodiester bonds in a polynucleotide chain?

  1. Lipase

  2. Protease

  3. Exonuclease

  4. Endonuclease


Correct Option: D
Explanation:

Endonucleases hydrolyse internal phosphodiester bonds in a polynucleotide chain. Function of nucleases is to break phosphodiester bond. A nuclease is an enzyme capable of cleaving the phosphodiester bonds between the nucleotide subunits of nucleic acids. Nucleases are usually further divided into endonucleases and exonucleases, although some of the enzymes may fall in both categories. 

Who coined the term enzyme?

  1. Pasteur

  2. Buchner

  3. Kuhne

  4. Sumner


Correct Option: C
Explanation:

Enzymes are biological catalysts, which activate various biochemical reactions of a living cell in a highly specific and precise manner. Enzymology is the study of enzymes. The name enzyme was coined by Kuhne in 1878. Pasteur recognised that some microorganisms like yeasts have got a capacity to cause fermentation in wine. In 1897, Buchner discovered that yeast extract could bring about fermentation of grape juice, like the living yeast cells. He also observed that the extract has lost its catalytic activity on boiling. He coined the word zymase for the active principle involved in the fermentation. The substance on which the enzyme acts is called substrate. Enzymes are essentially proteins but all proteins are not enzymes.

What did Kuhne do?

  1. Discovered parathyroid

  2. Coined the term enzyme

  3. Coined the term gene

  4. Discovered enzyme


Correct Option: B
Explanation:
  • In 1897, Eduard Buchner discovered that yeast extracts could ferment sugar to alcohol, proving that fermentation was promoted by molecules that continued to function when removed from cells. Frederick W. Khne called these molecules like enzymes.
    Hence, the correct option is B.

Enzymes that catalyse endergonic synthesis, coupled with exergonic hydrolysis of ATP are

  1. Ligases

  2. Isomerases

  3. Lyases

  4. Transferases


Correct Option: A
Explanation:
There are six major classes of enzymes, as follows:
(1) Oxidoreductases - Catalyze oxidationreduction reactions.
(2) Transferases - Catalyze the transfer of a functional group from a donor molecule to an acceptor molecule.
(3) Hydrolases - Catalyze hydrolysis reactions. 
(4) Isomerases - Catalyze conversion of a molecule from one isomeric form to another.
(5) Ligases - Ligases or synthetases are enzymes that catalyse endergonic synthesis, coupled with the exergonic hydrolysis of ATP
(6) Lyases - Catalyze certain reactions in which double bonds form or break.

Which enzyme act as chromosomal breaks?

  1. DNA polymerase

  2. DNase

  3. DNA ligase

  4. DNA polymerase II


Correct Option: B
Explanation:

The enzyme that cause chromosomal breaks are DNase. A deoxyribonuclease or DNase, is any enzyme that catalyzes the hydrolytic cleavage of phosphodiester linkages in the DNA backbone, thus degrading DNA. Deoxyribonucleases are one type of nuclease, a generic term for enzymes capable of hydrolising phosphodiester bonds that link nucleotides.

Enzyme were discovered for the first time in

  1. Bacteria

  2. Yeast

  3. Algae

  4. Spinach


Correct Option: B
Explanation:

Enzymes are biological catalysts, which activate various biochemical reactions of a living cell in a highly specific and precise manner. Enzymology is the study of enzymes. The name enzyme was coined by Kuhne in 1878. Pasteur recognised that some microorganisms like yeasts have got a capacity to cause fermentation in wine. In 1897, Buchner discovered that yeast extract could bring about fermentation of grape juice, like the living yeast cells. He also observed that the extract has lost its catalytic activity on boiling. He coined the word zymase for the active principle involved in the fermentation. The substance on which the enzyme acts is called substrate. Enzymes are essentially proteins but all proteins are not enzymes.

Who coined the term zymase? 

  1. Pasteur

  2. Buchner

  3. Kuhne

  4. Sumner


Correct Option: B
Explanation:

Buchner coined the term zymase for the complex of biocatalysts extracted from yeast and taking part in alcoholic fermentation. Pasteur is responsible for the process of pasteurization and Kuhne is best known today for coining the word enzyme.

Which of the following set of three items are true, as each set belongs to the category mentioned against them?

  1. Lysine, glycine, thiamine - Amino acids

  2. Myosin, oxytocin and gastrin - Hormones

  3. Rennin, helicase and hyaluronidase - Enzyme

  4. Optic nerve, oculomotor, vagus - Sensory nerves


Correct Option: C
Explanation:

Rennin is a protease found in rennet. It is produced by newborn ruminant animals in the lining of the fourth stomach to curdle the milk they ingest, allowing a longer residence in the bowels and better absorption. It is widely used in the production of cheese.

Helicases are enzymes that bind and may even remodel nucleic acid or nucleic acid protein complexes. There are DNA and RNA helicases. DNA helicases are essential during DNA replication because they separate double-stranded DNA into single strands allowing each strand to be copied.
Hyaluronidase is a protein enzyme. It works by causing rapid spreading of injected fluid into the body, which increases the absorption of injected fluids.
Therefore, the correct answer is option C.

Enzyme concerned with transfer of electrons are

  1. Hydrolase

  2. Dehydrogenase

  3. Transaminase

  4. Protease


Correct Option: B
Explanation:

Dehydrogenases are the enzymes which catalyze oxidation-reduction reactions by addition or removal of electrons. These reactions are used to synthesize reduced coenzymes like NADH$ _2$ and FADH$ _2$. For example phosphoglyceraldehyde dehydrogenase.

So, the correct answer is 'Dehydrogenase'.

Which enzyme shows greatest substrate specificity?

  1. Nuclease

  2. Trypsin

  3. Sucrase

  4. Pepsin


Correct Option: C
Explanation:
Enzymes are highly specific catalysts and show high degree of substrate specificity. Some enzymes names are general and these enzymes act on a type of biomolecules. For example: nucleases means enzymes acting on nucleic acids. Nuclease is a general class of enzyme. Similarly, pepsin and trypsin are protein metabolising enzymes. These enzymes will act on any proteins and not on some specific protein. Sucrase is, however, a specific enzyme which will act on sucrose only.
So, the correct answer 'Sucrase'

Non-proteinaceous enzyme that acts as a catalyst for the formation of peptide bond is
OR
"All enzymes are proteins." This statement is now modified because an apparent exception to this biological truth is

  1. Spliceosome

  2. Ribozyme

  3. RNA polymerase I

  4. RNA polymerase III


Correct Option: B
Explanation:

Ribozymes or RNA enzymes are catalytic RNA molecules. The first ribozyme discovered was self splicing group I intron. The second catalytic RNA was RNAase P which separates tRNA from hn RNA at their 5' ends. Peptidyl transferase involved in translation of proteins is also catalytic RNA. Telomerase is a ribonulceoprotein  enzyme. It is involved in replication of terminal DNA or telomeres.

Molecular scissors which cut DNA at specific site is known as

  1. Pectinase

  2. Polymerase

  3. Restriction endonuclease

  4. Ligase


Correct Option: C
Explanation:

A restriction enzyme or restriction endonuclease or molecular scissors is an enzyme used in genetic engineering that splices DNA at or near specific recognition nucleotide sequences, known as restriction sites. Thus, the correct answer is option C.

Which of the following enzyme is not of protein origin?

  1. Hexokinase

  2. Synthetase

  3. Endonuclease

  4. Ribozyme


Correct Option: D
Explanation:

Enzymes are biological catalysts which catalyse the biochemical reactions in living systems. Majority of enzymes are proteins. A small minority of enzymes are catalytic RNA molecules. These catalytic RNA molecules are called ribozymes. These catalytic RNA molecules catalyze reactions like splicing of introns during processing of RNA in eukaryotic mRNA.

Telomerase is an enzyme which is a

  1. Simple protein

  2. RNA

  3. Ribonucleoprotein

  4. Repetitive DNA


Correct Option: C
Explanation:
Telomerase is a ribonucleoprotein enzyme which adds bases at the 3' end of one strand of telomere as directed by the RNA sequence of RNA component of this enzyme.
So, the correct answer is 'Ribonucleoprotein'

Which of the following enzymes has/have heme as a prosthetic group?
(i) Catalase                            

(ii) Carboxypeptidase
(iii) Succinic dehydrogenase 

(iv) Peroxidase

  1. (i) Only

  2. (i) and (ii)

  3. (ii) and (iii)

  4. (iii) and (iv)

  5. (i) and (iv)


Correct Option: E
Explanation:

Co-enzymes tightly or covalently bonded to enzymes are called prosthetic groups, e.g., pyridoxal phosphate, heme, biotin. Heme is a prosthetic group containing ferrous ion. It is important for a number of biologically important hemoproteins such as myoglobin, cytochrome oxidase, catalase and peroxidase. Thus, the correct answer is option E.

Which one of the following enzyme contains 'Mn' metallic ion as the prosthetic group?

  1. Phosphatase

  2. Dehydrogenase

  3. Peptidase

  4. Catalase


Correct Option: C
Explanation:

Prosthetic groups are tightly bound cofactors. Peptidase enzymes hydrolyze peptide bonds. Peptidase enzymes require manganese ion for their activity as prosthetic group.

In which one of the following enzymes, is copper necessarily associated as an activator?

  1. Lactic dehydrogenase

  2. Tyrosinase

  3. Carbonic anhydrase

  4. Trytophanase


Correct Option: B
Explanation:

Some enzymes require metal ions for their activity. Tyrosinase is a copper containing enzyme that catalyzes the production of melanin and other pigments.

Most of the digestive enzymes belong to the class of

  1. Lyases

  2. Hydrolases

  3. Oxidoreductases

  4. Transferases


Correct Option: B
Explanation:

Hydrolase enzymes break large molecules into small molecules with the help of hydrogen and hydroxyl group of water molecules. The phenomenon is known as hydrolysis. Digestive enzymes in our body help to break down macromolecules of food into smaller molecules by the process of hydrolysis. So, digestive enzymes belong to the class Hydrolases. Thus, the correct option is B.

A simple enzyme is 

  1. Succinate dehydrogenase

  2. Urease

  3. Transaminase

  4. Ribozyme


Correct Option: B
Explanation:

Simple enzymes consist of only proteins and catalyze their substrate specific reactions. Urease is an enzyme which is only made up of protein and it functions to catalyze the hydrolysis of urea which results in the formation of ammonia and carbon dioxide.

Succinate dehydrogenase is an enzyme complex consisting of four polypeptides (SDH A-D) which catalyses the conversion of succinate to fumarate during cellular respiration.
Transaminase signifies a group of enzymes which catalyze transamination reaction.
Ribozymes are also called catalytic RNAs. These are RNA enzymes catalyzing peptide bonding reaction during protein synthesis.
Thus, the correct answer is 'Urease is a simple enzyme'.

Hydrolysis of starch occurs with the help of

  1. Sucrase

  2. Amylase

  3. Peptidase

  4. Lipase


Correct Option: B
Explanation:

Starch is used as food reserves in plants. It is a polymer of glucose. It is formed by the attachment of glucose unit by glycosidic bonds. The basic formula of starch is (C$ _6$H$ _{10}$O$ _5$)n. 

Amylase is an enzyme which helps in the digestion of the starch. It acts on the glycosidic bonds of the starch and converts into simpler compounds. It helps in the hydrolysis of this bond. It is present in the saliva and the pancreas secretion in humans and helps in intracellular digestion of starch.
So, the correct answer is option B.

Enzymes catalysing removal of groups and formation of double bond are

  1. Transferases

  2. Ligases

  3. Lyases

  4. Oxidoreductases


Correct Option: C
Explanation:

Lyase is the enzyme by which the chemical bonds are broken down by the process other than hydrolysis and oxidation. It allows the formation of new bond. 

Ligase are the enzyme which catalyzes the joining of two large molecules by formation of chemical bonds.
Oxoreductase are the enzyme which catalyzes the oxidation and reduction reaction.

Transferase involves the transfer of functional group from one molecule to the other.
So, the correct answer is option C.

Enzymes which catalyse reactions involving changes in structure of a molecule are

  1. Ligases

  2. Isomerases

  3. Hydrolases

  4. Transferases


Correct Option: B
Explanation:
Enzyme catalyzing optical or geometrical rearrangement of atomic groupings without altering molecular weight or number of atom is isomerase. It converts into from one isomer to the other isomer by changing the intramolecular arrangement by forming or breaking the bond. For, example glucose 6 phosphate is changed to fructose 6 phosphate by enzyme isomerase during the process of glycolysis.
Ligase is a enzyme which is used to join two molecules by establishing covalent bonds. Two DNA molecules are joined together by phosphodiester bond in presence of DNA ligase. The enzyme cannot be used for the blunt end of the DNA fragments. The nature of the bond is covalent as it involves the exchange of electrons.
Hydrolase are the enzyme which catalyses the splitting of compounds by addition of water.
Transferases helps to transfer functional group from one molecule to another.
So, the correct answer is option B.

Class of enzymes contained in lysosome

  1. Lyases

  2. Ligases

  3. Hydrolases

  4. Transferases


Correct Option: C
Explanation:
Lysosomes are formed by Golgi bodies. These are membrane-bounded vesicles which contain digestive and hydrolase enzymes like glycosidases, proteases, nucleases, phospholipases, and sulfatases. The enzymes are synthesized in the mRNA transcripts exit the nucleus into the cytosol, where they are translated by rough endoplasmic reticulum. The enzymes leave the Golgi apparatus as a vesicle known as lysosomes. 
So, the correct answer is option C.

Name the type of enzyme involved in the following reaction $S-G+{S}^{'} \longrightarrow S-{S}^{'}+G$.

  1. Dehydrogenase

  2. Transferase

  3. Hydrolase

  4. Lyase


Correct Option: B
Explanation:

Transferase is an enzyme that transfers a specific functional groups from one molecule to another. 

Enzyme catalyzing optical or geometrical rearrangement of atomic groupings without altering molecular weight or number of atom is isomerase. It converts into from one isomer to the other isomer by changing the intramolecular arrangement by forming or breaking the bond. 
Dehydrogenase is an enzyme which participates in the oxidoreductase reaction by using a electron acceptor.
Hydrolase are the enzyme which catalyses the splitting of compounds by addition of water.
Lyase is the process by which the chemical bonds are broken down by the process other than hydrolysis and oxidation. It allows the formation of new bond. 
So, the correct answer is option B.

Arginosuccinase is a .............. enzyme.

  1. Hydrolase

  2. Ligase

  3. Lyase

  4. Oxido-reductase


Correct Option: C
Explanation:

Hydrolase is a class of enzyme which act as biochemical catalysts that use water to break chemical bonds.

Ligase is an enzyme which catalyses the joining of two large molecules by forming a new bond generally accompanied by hydrolysis of a small chemical group.
Lyase is an enzyme which catalyses the breaking of C-C, C-O and C-N bonds by any methods other than hydrolysis or oxidation. Arginosuccinase is an enzyme which catalyses the breakdown of argininosuccinate producing arginine and fumarate.
Oxido-reductase is an enzyme which catalyses the transfer of electrons from the molecule of the reductant which acts as the electron donor to another molecule of the oxidant which accepts the electron.
So, the correct answer is 'Lyase'.

Which one of the following enzymes is added in many detergents that help of remove pertinacious stains from clothes?

  1. Alcalase

  2. Xylanase

  3. Peroxidase

  4. Catalase


Correct Option: A

Enzyme involved in transfer of electrons belongs to 

  1. Hydrolase

  2. Desmolase

  3. Transaminase

  4. Dehydrogenase


Correct Option: D
Explanation:

Dehydrogenase is an enzyme which participates in the oxidoreductase reaction by using an electron acceptor. It is involved in the transfer of electrons because it oxidizes a substrate by reducing it which means it transfers the electron from the substrate to an electron acceptor. Succinate dehydrogenase is an enzyme which is present in the inner mitochondrial membrane. It catalyzes the oxidation of succinate to fumarate.

So, the correct answer is option D.

Lactose metabolising enzyme, produced in the presence of lactose only is

  1. Inducible enzyme

  2. Repressible enzyme

  3. Regulatory enzyme

  4. Constitutive enzyme


Correct Option: A

Consider the following compounds.
a. Pyridoxal phosphate
b. Tetrahydrofdlate
c. Thaimine pyrophosphate
d. Lipoid acid
Which of the above belong to the coenzymes of Pyruvate dehydrogenate complex?

  1. $1$ only

  2. $2$ only

  3. Both $1$ and $2$

  4. Neither $1$ nor $2$


Correct Option: A

Match List I with List II and select the correct answer.

List-I(Enzymes) List-II(Characteristic Activity)
a. Terminal transferees $1$. Stable above $90$ degrees C
b. Polynucleotide kinesis $2$. Cleave the ends of linear DNA
c. Taq DNA polymerases $3$ Adds phosphate to $5$ OH end of DNA or RNA
d. Exonucleases $4$. Adds a number of nucleotides to $3'$ end of DNA or RNA
$5$. Regulate the level of super coiling of DNA molecule
  1. A-$5$, B-$4$, C-$1$, D-$2$

  2. A-$4$, B-$3$, C-$1$, D-$2$

  3. A-$3$, B-$4$, C-$5$, D-$1$

  4. A-$4$, B-$3$, C-$2$, D-$1$


Correct Option: A

Enzymes catalysing removal of group and formation of double bonds are 

  1. Ligases

  2. Lyases

  3. Transferases

  4. Oxidoreductases


Correct Option: B
Explanation:

Lyases is an enzyme which catalyses the joining of specified molecules or groups by a double bond. Lyases catalyze reactions where functional groups are added to break double bonds in molecules or the reverse where double bonds are formed by the removal of functional groups. So, the correct answer is option B.

Which one of the following is not a thenno stable enzyme?

  1. Taq DNA polymerase

  2. RNA polymerase

  3. Pfu DNA polymerase

  4. Vent polymerase


Correct Option: A

The catalytic power of enzyme is represented by _____________.

  1. $V _{max}$

  2. $K _{m}$ constant

  3. Turn over number

  4. Both (2) and (3)


Correct Option: A
Explanation:
The catalytic power of an enzyme is basically the enzyme’s turnover. It is generally denoted by  $V _m$$ _a$$ _x$
So, the correct answer is $V _m$$ _a$$ _x$.

The catalytic efficiency of two different enzyme can be compared by the:

  1. The Kim value

  2. The pH optimum value

  3. Formation of the product

  4. Molecular size of the enzyme


Correct Option: A
Explanation:
The $K _m$ is also known as Michaelis-Menten constant. It represents the substrate concentration at which the rate of a reaction is half the maximum rate. It is an important parameter to compare catalytic efficiency of two enzymes. Lower the $K _m$ , higher will be the catalytic rate and vice-versa.

The fastest acting enzyme in the biological kingdom is

  1. Lipase

  2. Amylase

  3. Carboxypeptidase

  4. Carbonic anhydrase


Correct Option: D
Explanation:

In enzymology, turnover number is the number of substrate molecules converted to products in a given unit of time on a single enzyme molecule when the enzyme is saturated with substrate. The enzyme catalase has highest turnover number value of 40,000,000 (per second per molecule of enzyme), followed by Carbonic anhydrase 400,000 (per second per molecule of enzyme), followed by acetylcholinesterase 140,000 (per second per molecule of enzyme), followed by $\beta$-lactamase 2000 (per second per molecule of enzyme).

Match the scientists and their contribution given in the columns.


Scientists Contribution
A. Pasteur p. Beer and butter milk are products of fermentation by yeast
B. Hansen q. Diastase
C. Payen and Persoz  r. Purified rennet 
D. Waksman s. Streptomycin

  1. A - p, B - q, C - r, D - s

  2. A - p, B - r, C - q, D - s

  3. A - p, B - s, C - r, D - q

  4. A - s, B - r, C - q, D - p


Correct Option: B
Explanation:

The scientists listed in question had made some of the most outstanding contributions.
Pasteur discovered fermentation.  The biochemical process carried out by yeast which results in fermented products like beer and butter milk.
The first commercial standardized rennet was introduced by Chr Hansen in 1874. At that time, rudimentary methods were used to extract animal rennet from calves or adult bovine stomachs.
Diastase was the first enzyme discovered. It was extracted from malt solution in 1833 by Anselme Payen and Jean-Franois Persoz, chemists at a French sugar factory.
Waksman was awarded the Nobel Prize in Physiology or Medicine in recognition for his discovery of streptomycin, the first antibiotic active against tuberculosis.

In 1930, John Northrop crystallized which of the following enzyme as a protein?

  1. Pepsin

  2. Renin

  3. Amylase

  4. Trypsin


Correct Option: A
Explanation:
In 1930, Northrop isolated a crystalline substance from a commercial pepsin preparation, and the crystallized substance appeared to be the enzyme pepsin.

The enzyme which has EC number 4.2.1.7 is assigned to which of the following classes of enzyme?

  1. Hydrolases

  2. Lyases

  3. Isomerases

  4. Ligases


Correct Option: B
Explanation:

The EC number 4.2.1.7 is assigned to the enzyme named altronate dehydratase or D-altronate hydro-lyase. This enzyme catalyses the dehydration of D-altronate and results in the formation of 2-dehydroxy-3-deoxy-D-gluconate and water. 

Thus, the answer is B, i.e., the enzyme which has EC number 4.2.1.7 is assigned to the class of Lyases.

Phosphodiesterases rapidly catalyze hydrolysis of sugar phosphate bond in nucleic acids.
The first digit of their E,C number can be

  1. $1$

  2. $2$

  3. $3$

  4. $6$


Correct Option: C
Explanation:

Phosphodiesterase is a hydrolase enzyme. So, it's EC number is 3.

EC or Enzyme Commission number is numerical classification scheme for enzymes, used to classify them according to reactions they catalyze.
So, the correct  option is '3'.

In recent years, pre-soaked laundry agent (detergent) contains an enzyme

  1. Pepsin

  2. Flavin

  3. Amylase

  4. Subtilin


Correct Option: D
Explanation:

Natural source of subtilin is bacteria Bacillus subtilis. Subtilisins are proteolytic enzymes mainly used in detergents and house hold cleaning products to remove proteinaceous deposits and stains.

Histones associated with the genetic material apart from maintaining its also act as

  1. Modulators

  2. Apozymes

  3. Isozymes

  4. Activators


Correct Option: A
Explanation:

Histone proteins are rich in basic amino acids and form the core around which the DNA is wound giving rise to nucleosome particles. DNA is wound around histones because basic amino acids are positively charged at physiological pH which facilitates winding of acidic or negatively charged DNA. Neutralization of positive charge, on basic amino acids of histone proteins, by chemical processes like reversible acetylation will lead to neutralization of attractive force between nucleosome core and DNA molecule. This will in turn lead to transcriptional activation (histone proteins are acetylated) and after transcription once again the histone proteins will be deacetylated restoring there positive charge, thus facilitating the tight binding between (negatively charged) DNA and (positively charged) histone core. Apart from reversible acetylation, histone proteins also undergo a number of other chemical modifications. Thus, acting as modulators for DNA metabolism.

The first enzyme isolated in crystalline form was 

  1. Catalase

  2. Urease

  3. Peroxidase

  4. Amylase


Correct Option: B
Explanation:

in 1897, Eduard Buchner discovered that yeast extracts could ferment sugar to alcohol, proving that fermentation was promoted by molecules that continued to function when removed from cells. Frederick W. Khne called these molecules as enzymes. The isolation and crystallization of urease by James Sumner, in 1926, provided a breakthrough in early enzyme studies. Sumner found that urease crystals consisted entirely of protein, and he postulated that all enzymes are proteins. In the absence of other examples, this idea remained controversial for some time. Only in the 1930s, was Sumners conclusion widely accepted, after John Northrop and Moses Kunitz crystallized pepsin, trypsin, and other digestive enzymes and found them also to be proteins.

Which one of the following is not true for an iso-enzymes?

  1. Iso enzymes are quartenary proteins.

  2. All forms synthesized by different genes.

  3. Increase activation energy of substrate.

  4. All of the above.


Correct Option: C
Explanation:

Isoenzymes are an unique example in which the same reaction may be catalyzed by two or more different molecular forms of an enzyme. The multiple forms, called isozymes or isoenzymes, may occur in the same species, in the same tissue, or even in the same cell. The different forms of the enzyme generally differ in kinetic or regulatory properties, in the cofactor they use (NADH or NADPH for dehydrogenase isozymes, for example), or in their subcellular distribution (soluble or membrane-bound). Isozymes may have similar, but not identical, amino acid sequences, and in many cases they clearly share a common evolutionary origin. One of the first enzymes found to have isozymes was lactate dehydrogenase (LDH), which, in vertebrate tissues, exists as at least five different isozymes separable by electrophoresis. However, isoenzymes follow the same general mechanism of enzyme action, i.e., decreasing the activation energy of substrates for a reaction.

Name the hormone that stimulate the secretion of gastric juice.

  1. Renin

  2. Enterokinase

  3. Enterogastrone

  4. Gastrin


Correct Option: D
Explanation:

Gastrin is a peptide hormone, which is secreted by the gastric glands in the stomach wall. The gastrin stimulates secretion of gastric juice rich in pepsin and hydrochloric acid. The stimulation for secretion of gastrin is presence of peptides derived from dietary proteins.

Proteinaceous nature of enzyme was suggested by

  1. T. Cech

  2. Kuhne

  3. E. Buchner

  4. Northrop


Correct Option: D
Explanation:

Enzymes are biological catalysts. The multitude of biochemical reactions that make cellular metabolism possible are due to enzymes. The isolation and crystallization of urease by James Sumner in 1926 provided a breakthrough in early enzyme studies. Sumner found that urease crystals consisted entirely of protein, and he postulated that all enzymes are proteins. In the absence of other examples, this idea remained controversial for some time. Only in the1930s, was Sumners conclusion widely accepted, after John Northrop and Moses Kunitz crystallized pepsin, trypsin, and other digestive enzymes and found them also to be proteins.

Enzyme amylase belongs to category 

  1. Oxidoreductases

  2. Transferases

  3. Hydrolases

  4. Isomerases


Correct Option: C
Explanation:

An amylase is an enzyme that catalyses the hydrolysis of starch into sugars. A hydrolase or hydrolytic enzyme is an enzyme that catalyzes the hydrolysis of a chemical bond. So, the correct answer is option C.

The enzyme which combines with a nonprotein prosthetic group to form a functional enzyme is called

  1. Apoenzyme

  2. Holoenzyme

  3. Coenzyme

  4. Proenzyme.


Correct Option: B
Explanation:

The non-protein component or prosthetic group along with the protein component or apoenzyme is called the holoenzyme. The prosthetic group may be metal ion or a co-enzyme that may be firmly or losely bound to the enzyme.
So, the correct answer is option B.

Enzymes generally have

  1. Same pH and temperature optima

  2. Same pH but different temperature optima

  3. Different pH but same temperature optima

  4. Different pH and different temperature optima


Correct Option: A
Explanation:

Enzymes are biocatalyst that affects the rate of biochemical reactions they generally have the same pH and temperature Optima at which they work efficiently. 

So, the correct option is 'Same pH and temperature optima'. 

Class of enzymes contained in lysosomes is 

  1. Lyases

  2. Ligases

  3. Hydrolases

  4. Transferases


Correct Option: C
Explanation:

A lysosome is a membrane-bound organelle found in nearly all animal cells. They are spherical vesicles which contain hydrolytic enzymes that can break down many kinds of biomolecules. So, the correct answer is option C.

Which is not a hydrolase?

  1. Protease

  2. Dehydrogenase

  3. Sucrase

  4. Amylase

  5. Esterase


Correct Option: B
Explanation:


A dehydrogenase is an enzyme that oxidizes a substrate by reducing an electron acceptor, usually a flavin coenzyme known as FMN.
While all other are hydrolases because they take part in the hydrolysis. 
So the correct answer is C.

Ribozyme is

  1. RNA with additional phosphate.

  2. RNA without sugar.

  3. RNA without uracil.

  4. RNA acting as enzyme.


Correct Option: D
Explanation:

Most of the enzymes are large protein molecules except for a small category of catalytic RNA molecules. The catalytic RNA molecules are called Ribozymes. Ribozymes play an important role in intron splicing and other reactions during processing of RNA. The ribozymes are an important example of self catalytic (RNA) molecules, i.e., one type of RNA (ribozyme) acting on another type of RNA (like mRNA). Some of the introns are self splicing which catalyze their own splicing.

Digestive enzymes are found in

  1. Lysosomes

  2. Mitochondria

  3. Chloroplast

  4. All of the above


Correct Option: A
Explanation:

Lysosomes are membrane-bound vesicles that contain digestive enzymes, such as glycosidases, proteases and sulfatases. Lysosomal enzymes are synthesized in the endoplasmic reticulum (ER), are transported to the Golgi apparatus, and are tagged for lysosomes by the addition of mannose-6-phosphate label. Digestive enzymes are not found in chloroplast and mitochondria. 

Therefore, the correct answer is option A.

Enzymes that catalyse inter-conversion of optical, geometrical or positional isomers are

  1. Ligases

  2. Lyases

  3. Hydrolases

  4. Isomerases


Correct Option: D
Explanation:

Ligases are the enzymes which catalyze joining together of two DNA segments. Lyases catalyze the breaking of chemical bonds without hydrolysis while hydrolases catalyze hydrolytic cleavage of bonds. Isomerases catalyze interconversion of optical, geometrical or positional isomers of a particular enzyme.

Endopeptidase of plant kingdom is

  1. Trypsin

  2. Pepsin

  3. Papain

  4. Urease


Correct Option: C
Explanation:

Endopeptidase are the proteolytic enzymes which cleave the peptide chain at internal locations. They break peptide bonds of non terminal amino acids (i.e. within the molecule), in contrast to exopeptidases, which break peptide bonds from their end-pieces. One example is papain obtained from unripe papaya.

One of the following enzyme is used to cut genes at specific sites, therefore, useful in recombinant technology

  1. Ligase

  2. Topoisomerase

  3. Pepsin

  4. Restriction endonuclease


Correct Option: D
Explanation:

Restriction endonuclease are a part of cellular defense system in bacteria. These enzymes cleave or restrict external or exogenous DNA. A type of these enzymes act on specific palindromic sequences which they recognize.

An organic substance bound to an enzyme and essential for its activity is called as

  1. Apoenzyme

  2. lsoenzyme

  3. Coenzyme

  4. Holoenzyme


Correct Option: C
Explanation:

Enzymes are simple if they are made up of only proteins, e.g., pepsin, amylase, etc., while conjugate enzymes have an additional non-protein cofactor, e.g., dehydrogenase enzymes. The cofactor can be organic or inorganic. Loosely attached organic cofactor are called coenzymes, e.g., NAD, FAD etc., while firmly attached one is prosthetic group, e.g., haeme, biotin etc.

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