Enzymes Questions in English

(B) $Papain$ is a proteolytic enzyme (endopeptidase) extracted from the latex of the papaya plant $(Carica\,papaya)$. It is a plant-derived proteinase. In contrast, $Pepsin$ and $Trypsin$ are animal-derived digestive enzymes, and $Urease$ is an enzyme that catalyzes the hydrolysis of urea.

(D) During the germination of cotton seeds,the stored food reserves (primarily starch) are broken down to provide energy for the developing embryo.
$Amylase$ is the enzyme responsible for the hydrolysis of starch into simpler sugars,which are then utilized by the seedling for growth and development.

(B) Lipase is an enzyme that catalyzes the hydrolysis of fats (triglycerides) into their constituent components.
During the process of digestion,lipase breaks down a triglyceride molecule into one molecule of glycerol and three molecules of fatty acids.
Therefore,the correct products of fat hydrolysis by lipase are glycerol and fatty acids.

(C) Amylase is an enzyme that catalyzes the hydrolysis of starch into sugars.
Starch is a polysaccharide composed of glucose units,and amylase specifically breaks the glycosidic bonds within the starch molecule.
Therefore,the substrate for amylase is starch.

(D) Amylase is an enzyme that catalyzes the hydrolysis of starch into sugars such as maltose.
$1.$ Lactase breaks down lactose into glucose and galactose.
$2.$ Protease breaks down proteins into peptides or amino acids.
$3.$ Maltase breaks down maltose into glucose.
$4.$ Amylase specifically acts on starch to produce maltose.

(A) Hydrolases are enzymes that catalyze the hydrolysis of chemical bonds.
$Protease$, $Amylase$, and $Esterase$ are all examples of hydrolases because they break down substrates by adding water.
$Dehydrogenase$ is an enzyme that belongs to the class of oxidoreductases, as it catalyzes the removal of hydrogen atoms from a substrate.
Therefore, $Dehydrogenase$ is not an example of a hydrolase.

(A) Castor seeds $(Ricinus communis)$ store food primarily in the form of lipids (fats/oils) within their endosperm.
Lipase is the enzyme responsible for the hydrolysis of these stored lipids into fatty acids and glycerol during seed germination.
Therefore, the correct enzyme is Lipase.

(B) Enzymes are classified into six major classes based on the type of reaction they catalyze.
$1$. Oxidoreductases/Dehydrogenases: These enzymes catalyze oxidoreduction between two substrates by the transfer of electrons or hydrogen atoms.
$2$. Hydrolases: These catalyze the hydrolysis of ester,ether,peptide,or glycosidic bonds.
$3$. Transaminases (Transferases): These catalyze the transfer of a group other than hydrogen between a pair of substrates.
$4$. Desmolases: These are enzymes that catalyze the breaking of carbon-carbon bonds.
Therefore,enzymes concerned with the transfer of electrons are Dehydrogenases.

(B) Enzymes are classified into six major groups based on the type of reaction they catalyze.
Transferases are enzymes that catalyze the transfer of a functional group (e.g.,methyl,amino,or phosphate group) from one molecule (the donor) to another (the acceptor).
Transaminase is a classic example of a transferase,as it catalyzes the transfer of an amino group from an amino acid to an $\alpha$-keto acid.
Amylase is a hydrolase,Citrate synthetase is a ligase,and Enolase is a lyase.

(C) Enzymes are classified into six main classes based on the type of reaction they catalyze.
Esterase is an enzyme that catalyzes the hydrolysis of ester bonds into an acid and an alcohol.
Since it involves the addition of water to break a chemical bond,it is classified under the class of Hydrolases.

(A) Hydrolases are enzymes that catalyze the hydrolysis of chemical bonds,typically by adding water across the bond.
Amylase is a hydrolase that catalyzes the hydrolysis of starch into sugars.
Transaminase belongs to the transferase group.
Citrate synthetase belongs to the ligase group.
Enolase belongs to the lyase group.
Therefore,the correct option is $A$.

(C) Enzymes are proteins composed of amino acids linked by peptide bonds.
Peptidases are enzymes that catalyze the hydrolysis of peptide bonds in proteins.
Since other enzymes are also proteins,they can be broken down or digested by peptidases (proteases).
Dehydrogenases,lipases,and aldolases have specific substrates like alcohols,lipids,and sugars/intermediates respectively,and do not primarily digest proteins.

(B) Nucleic acids are polymers of nucleotides. The enzymes that specifically act on nucleic acids to break them down into their constituent nucleotides are known as nucleases. Amylases break down carbohydrates,lipases break down lipids,and proteases break down proteins.

(A) Enzymes are proteinaceous in nature. At high temperatures, such as boiling temperature $(100^{\circ}C)$, the weak hydrogen bonds and other interactions that maintain the tertiary and secondary structure of the protein are broken. This leads to the loss of the specific three-dimensional shape of the enzyme, a process known as denaturation. Since the active site of the enzyme is dependent on this specific shape, the enzyme loses its catalytic activity permanently.

(B) Digestion in seeds involves the breakdown of stored food materials (like starch,proteins,and fats) into simpler,absorbable forms to support germination.
This process is catalyzed by biological catalysts known as enzymes.
Enzymes lower the activation energy required for these biochemical reactions,allowing them to occur efficiently at relatively low temperatures found in the environment.

(C) Zymogens are inactive precursors of enzymes. They are synthesized and secreted in an inactive form to prevent premature digestion of the tissues that produce them. They are converted into their active enzymatic forms through specific biochemical modifications,such as proteolytic cleavage,when they reach their site of action.

(A) $Isoenzymes$ are different forms of an enzyme that catalyze the same chemical reaction.
They may differ in their amino acid sequences, molecular structure, and physical properties, but they perform the same catalytic function.
For example, $Lactate$ $dehydrogenase$ $(LDH)$ exists in multiple isoenzyme forms.

(A) Isoenzymes (or isozymes) are enzymes that differ in amino acid sequence and molecular structure but catalyze the same chemical reaction.
For example,Lactic dehydrogenase $(LDH)$ exists in $5$ different isoenzyme forms in humans,all of which catalyze the conversion of pyruvate to lactate.

(C) Lactic dehydrogenase $(LDH)$ is an enzyme that exists in multiple molecular forms within the same species,all of which catalyze the same chemical reaction (the interconversion of pyruvate and lactate).
Such enzymes,which differ in their amino acid sequences and physical properties but perform the same catalytic function,are known as isoenzymes (or isozymes).
Therefore,$LDH$ is a classic example of an isoenzyme.

(C) Isoenzymes (or isozymes) are enzymes that differ in amino acid sequence and physical properties (such as electrophoretic mobility or thermal stability) but catalyze the same chemical reaction. Therefore,they are physically and chemically different but perform the same biological function. Option $C$ is the most accurate description of this phenomenon.

(A) Ribozyme is a non-protein enzyme, which is an $RNA$ molecule capable of catalyzing specific biochemical reactions.
It was first discovered in $Tetrahymena$ (a protozoan) by $Thomas Cech$.
Unlike most enzymes which are proteins, ribozymes are composed of ribonucleic acid $(RNA)$.

(B) $J.B. Sumner$ $(1926)$ was the first to isolate and crystallize an enzyme,which was $Urease$ from jack bean.

(C) Enzymes are highly specific biological catalysts that function optimally under specific environmental conditions.
Each enzyme has a specific $pH$ range at which it exhibits maximum activity,known as its $pH$ optimum,which varies significantly depending on the enzyme's structure and its site of action (e.g.,pepsin in the stomach vs. trypsin in the small intestine).
However,most enzymes found within the same organism typically share a similar temperature optimum,which is generally close to the body temperature of that organism,as they have evolved to function efficiently at that specific thermal range.
Therefore,enzymes generally have different $pH$ optima but the same temperature optima.

(C) Biochemical reactions in living organisms are distinct from those in the non-living world primarily because they are catalyzed by enzymes.
In the non-living world,chemical reactions often require inorganic catalysts or high temperatures/pressures to proceed at a significant rate.
In contrast,living systems utilize enzymes,which are biological catalysts (mostly proteins),to lower the activation energy and facilitate reactions under physiological conditions.

(C) The most important property of an enzyme is its specificity.
This is because each enzyme is designed to catalyze only a specific type of chemical reaction or act on a specific substrate,ensuring metabolic precision within the cell.

(C) Enzymes are biocatalysts that accelerate chemical reactions by lowering the activation energy,often by more than $50\%$.
They function extremely efficiently,and in many biological systems,the ratio of enzyme molecules to substrate molecules can be as high as $1 : 10,00,000$.
This high efficiency allows cells to carry out complex metabolic processes at very high speeds.

(A) The template theory,also known as the $Lock$ and $Key$ hypothesis,suggests that an enzyme has a specific active site that fits a specific substrate perfectly,much like a key fits a lock.
Competitive inhibition provides the best evidence for this theory.
When a compound that is structurally similar to the substrate (a competitive inhibitor) binds to the active site,it prevents the actual substrate from binding.
This demonstrates that the enzyme's active site is specific to a particular molecular shape,which is the core principle of the template theory.

(A) Competitive inhibition occurs when the inhibitor closely resembles the substrate in its molecular structure and competes for the active site of the enzyme.
Because the inhibitor and the substrate compete for the same active site,the inhibition can be overcome by significantly increasing the concentration of the substrate.
By increasing the substrate concentration,the probability of the substrate binding to the active site increases,effectively outcompeting the inhibitor.

(A) According to the International Union of Biochemistry and Molecular Biology $(IUBMB)$,enzymes are classified into $6$ main classes based on the type of reaction they catalyze.
The $6$ classes are:
$1$. Oxidoreductases
$2$. Transferases
$3$. Hydrolases
$4$. Lyases
$5$. Isomerases
$6$. Ligases
Therefore,Ligases occupy the $6^{th}$ position.

(D) Simple proteins are those that consist only of amino acids without any non-protein prosthetic groups.
Amylase is a simple protein enzyme that catalyzes the hydrolysis of starch into sugars.
In contrast,enzymes like peroxidase often require non-protein cofactors (like heme) to function,making them conjugated proteins.

(A) Enzymes are classified based on the type of reaction they catalyze.
Arginase is an enzyme that catalyzes the hydrolysis of $L$-arginine to $L$-ornithine and urea.
Since urea contains an amide group and the reaction involves the hydrolysis of a carbon-nitrogen bond (specifically in the guanidino group of arginine),Arginase is classified as an amidase (a subclass of hydrolases).
Therefore,Arginase is the correct example of an amide enzyme.

(C) Cytochrome $P_{450}$ is a large and diverse superfamily of hemoproteins (containing iron) that function as monooxygenases.
They play a crucial role in the metabolism of various endogenous and exogenous substances,including drugs and toxins,primarily through oxidation reactions.
Cytochrome $P_{450}$ is an enzyme,not a cell.
Therefore,the statement that it is a 'coloured cell' is incorrect.

(A) The enzyme $Lipase$ acts on $Lipids$ or $Fats$. It hydrolyzes $Triglycerides$ into $Fatty\,acids$ and $Glycerol$.

(B) Growth is an irreversible increase in size,mass,or volume of an organism. During this process,enzymes act as biological catalysts that facilitate metabolic reactions without being consumed in the reaction themselves. Therefore,enzymes remain chemically unchanged at the end of the growth process,whereas hormones,vitamins,and nucleotides are often consumed,modified,or utilized in the synthesis of new cellular components.

(D) The enzyme arginase is primarily found in the liver. It plays a crucial role in the urea cycle (also known as the ornithine cycle),where it catalyzes the hydrolysis of arginine into ornithine and urea.

(C) $1, 4$ Glycosidic bonds are the primary linkages found in the polysaccharide starch (amylose and amylopectin).
Amylase is an enzyme that specifically catalyzes the hydrolysis of these internal $\alpha-1, 4$ glycosidic linkages in starch molecules to break them down into smaller sugar units like maltose and dextrins.
Therefore,the correct option is $C$.

(A) Amylase is a digestive enzyme that catalyzes the hydrolysis of starch into sugars.
Starch is a polysaccharide,and amylase breaks it down into smaller carbohydrate units like maltose and dextrins.
Therefore,the substrate for amylase is starch.

(A) The enzyme invertase (also known as sucrase) is responsible for the hydrolysis of the disaccharide sucrose.
It catalyzes the breakdown of sucrose into its constituent monosaccharides,glucose and fructose.
The chemical reaction is: $\text{Sucrose} + \text{H}_2\text{O} \xrightarrow{\text{Invertase}} \text{Glucose} + \text{Fructose}$.

(A) Cathepsins are a class of lysosomal proteases that are active at acidic $pH$ values,typically ranging from $3.0$ to $5.0$. They play a crucial role in the intracellular degradation of proteins and are involved in various physiological processes such as tissue remodeling and protein turnover.

(C) The question describes the dissociation of a prosthetic group from the protein part (apoenzyme) of an enzyme.
In biochemical terminology,when a prosthetic group or cofactor is separated from the enzyme,the process is often referred to as dialysis in experimental setups to separate small molecules from proteins.
However,in the context of enzyme structure,the protein part is called the apoenzyme and the non-protein part is the cofactor.
Given the options provided,'Dialysis' is the standard laboratory technique used to separate small prosthetic groups or cofactors from the proteinaceous apoenzyme based on molecular size.

(C) $Pepsin$ is a proteolytic enzyme produced by the stomach that is responsible for initiating the digestion of proteins.

(D) $Amylase$ is a starch-splitting enzyme similar to ptyalin. It hydrolyzes starch and glycogen into maltose,isomaltose,and limit dextrin.

(A) $Isoenzymes$ are enzymes that exist in more than one form within the same species but catalyze the same chemical reaction. Although they have similar functions,they may differ in their amino acid sequences,physical properties,or regulatory mechanisms.

(B) Chemically, all enzymes are proteins, with the exception of ribozymes (which are $RNA$ molecules). However, in the context of general biological classification, enzymes are primarily composed of amino acids folded into specific three-dimensional structures. Therefore, the statement '$All$ $enzymes$ $are$ $proteins$' is the standard biological principle, although it is important to note that '$all$ $proteins$ $are$ $not$ $enzymes$'.

(A) Biocatalysts are substances,typically enzymes,that increase the rate of chemical reactions in living organisms.
$A$. Peptidase,amylase,and rennin are all enzymes (proteins) that catalyze the breakdown of peptides,starch,and milk proteins,respectively.
$B$. Myosin is a contractile protein,while oxytocin and adrenalin are hormones.
$C$. Rhodopsin is a pigment,while pepsin and steapsin are enzymes.
$D$. Glucose,amino acids,and fatty acids are simple biomolecules (monomers),not catalysts.
Therefore,the correct group is $A$.

(A) All enzymes are biological catalysts that are essentially proteinaceous in nature. Amylase,rennin,and trypsin are all enzymes; therefore,they are all proteins. While they differ in their specific substrates and sites of action,their fundamental chemical composition as proteins is the common factor.

(D) Enzymes,vitamins,and hormones are all essential biological molecules that play a critical role in the regulation of metabolic processes within living organisms.
Enzymes act as biological catalysts that speed up biochemical reactions.
Hormones act as chemical messengers that coordinate various physiological activities.
Vitamins act as co-factors or co-enzymes necessary for the proper functioning of enzymes.
Therefore,they are collectively involved in the regulation of metabolism.

(C) The $Km$ (Michaelis constant) is defined as the substrate concentration at which the reaction rate is half of the maximum velocity $(V_{max}/2)$.
For a specific enzyme-substrate pair under defined conditions (such as temperature and $pH$),the $Km$ value is a characteristic constant.
It reflects the affinity of the enzyme for its substrate; a lower $Km$ indicates higher affinity,while a higher $Km$ indicates lower affinity.

(D) The correct answer is $D$.
$DNA$ ligase is an enzyme that joins $DNA$ fragments together by forming phosphodiester bonds,rather than breaking them.
Option $A$ is correct as Lipase hydrolyzes fats into fatty acids and glycerol.
Option $B$ is correct as Isomerases catalyze the rearrangement of atoms within a molecule.
Option $C$ is correct as Polymerase enzymes are responsible for synthesizing new $DNA$ or $RNA$ strands by adding nucleotides.