Enzymes MCQ Quiz - Objective Question with Answer for Enzymes - Download Free PDF

The correct answer is lysosomes.

Key Points

• Lysosomes
  • These are membrane bound vesicular structures formed by the process of packaging in the golgi apparatus.
  • The isolated lysosomal vesicles have been found to be very rich in almost all types of hydrolytic enzymes (hydrolases – lipases, proteases, carbohydrases) optimally active at the acidic pH.
    • These enzymes are capable of digesting carbohydrates, proteins, lipids, and nucleic acids.

Important Points

• Vacuoles
  • The vacuole is the membrane-bound space found in the cytoplasm.
  • It contains water, sap, excretory product and other materials not useful for the cell.
  • The vacuole is bound by a single membrane called tonoplast.
  • In plant cells, the vacuoles can occupy up to 90% of the volume of the cell.
• Mitochondria
  • It is sausage-shaped or cylindrical having a diameter of 0.2-1.0µm (average 0.5µm) and length 1.0-4.1µm.
  • It is called the powerhouse of the cell.
  • Each mitochondrion is a double membrane-bound structure with the outer membrane and the inner membrane dividing its lumen distinctly into two aqueous compartments.
    • The outer compartment and the inner compartment.
    • The inner compartment is filled with a dense homogeneous substance called the matrix.
    • The outer membrane forms the continuous limiting boundary of the organelle.
• Ribosomes
  • Ribosomes are made up of RNA and proteins. 
  • The ribosomes, which are present in all active cells, are the sites of protein manufacture.
  • In prokaryotes, ribosomes are associated with the plasma membrane of the cell.

Key Points

• Enzymes can be defined as biological polymers that catalyze biochemical reactions.
• Enzymes are biocatalysts, which are high molecular weight proteinaceous compounds.
• The six kinds of enzymes are hydrolases, oxidoreductases, lyases, transferases, ligases, and isomerases.
• Catalysts are the substances which increase the rate of a chemical reaction without changing themselves.
• Biological catalysts, enzymes, are extremely specific and catalyze only a single or some closely associated reactions.

Enzymes are high molecular weight proteins that act as catalysts. So, the correct option is both A and B.

Important Points

Enzyme structure - 

• Enzymes are most commonly made of protein, except in the class of RNA catalysts called ribozymes.
• Enzymes are a linear chain of amino acids, which give rise to a three-dimensional structure.
• The enzyme comprises hollow spaces occupying groups such as -SH, -COOH, etc. called active sites.

​Enzyme action - 

• In a metabolic reaction, two molecules have to collide in the right orientation with sufficient energy for the reaction to occur.
• The energy required by these molecules to overcome the barrier in the reaction is called activation energy.
• The molecule that binds to the enzyme is referred to as the substrate group.
• It binds at the substrate binding site is called the active site of an enzyme (E).
• Enzymes convert the substrates into other distinct molecules, which are known as products.
• Initially, substrates associate themselves by noncovalent interactions with the enzymes which include ionic, hydrogen bonds, and hydrophobic interactions.
• Enzymes reduce the reaction activation energy to progress towards equilibrium quicker than the reactions that are not catalyzed.
• Enzymes are particular about the optimum conditions provided for the reactions such as temperature, pH, alteration in substrate concentration, etc.

Enzyme function - 

• They break down large molecules into smaller substances that can be easily absorbed by the body.
• They help in generating energy in the body. ATP synthase is the enzyme involved in the synthesis of energy.
• Enzymes are responsible for the movement of ions across the plasma membrane.
• Enzymes perform a number of biochemical reactions, including oxidation, reduction, hydrolysis, etc. to eliminate the non-nutritive substances from the body.​

Additional Information

Hormones - 

• Hormones are chemicals synthesized and produced by the specialized glands to control and regulate the activity of certain cells and organs.
• They are signaling molecules in multicellular organisms, that are transported to distant organs to regulate physiology and behavior.
• They are usually composed of proteins and act as chemical messengers.
• They are produced in very small quantities and released into the blood in the human body.

The correct answer is Trypsin and lipase.

Key Points

• Trypsin is a proteolytic enzyme secreted by the pancreas in its inactive form, trypsinogen, which is then activated in the small intestine.
• Lipase is an enzyme responsible for breaking down fats into fatty acids and glycerol, aiding in digestion.
• Both trypsin and lipase are vital components of pancreatic juice, which plays a key role in digestion in the small intestine.
• Pancreatic juice contains digestive enzymes that work on proteins, fats, and carbohydrates, making it essential for nutrient absorption.
• The pancreas also secretes bicarbonate ions in pancreatic juice, which help neutralize stomach acid in the small intestine.

Additional Information

• Pancreatic Juice: It is a clear, alkaline fluid secreted by the pancreas that contains enzymes like trypsin, lipase, and amylase.
• Proteolytic Enzymes: These enzymes, such as trypsin and chymotrypsin, break proteins into smaller peptides and amino acids during digestion.
• Lipase: Essential for fat digestion, lipase hydrolyzes triglycerides into free fatty acids and glycerol in the presence of bile salts.
• Amylase: Another enzyme in pancreatic juice, amylase aids in the breakdown of carbohydrates into simpler sugars like maltose and glucose.
• Activation of Enzymes: Pancreatic enzymes like trypsinogen are activated in the small intestine to prevent self-digestion of pancreatic tissues.

The correct answer is salivary amylase.

Key Points

• Salivary amylase is an enzyme produced by the salivary glands in the mouth.
• It is responsible for breaking down carbohydrates into simpler sugars during the process of digestion.
• The enzyme initiates the digestion of starches in the mouth, converting them into maltose and dextrin.
• Salivary amylase works best at a slightly alkaline pH, which is maintained in the mouth.

Additional Information

• Isomerase: An enzyme that catalyzes the conversion of a molecule from one isomer to another.
• Sucrase: An enzyme that catalyzes the hydrolysis of sucrose into glucose and fructose.
• Kinase: An enzyme that catalyzes the transfer of phosphate groups from high-energy donor molecules, such as ATP, to specific substrates.
• Salivary amylase is also known as ptyalin.
• Digestion begins in the mouth with the mechanical action of chewing and the chemical action of salivary amylase.

The Correct answer is Enzymes.

Key Points

• Enzymes are biological molecules that act as catalysts in living organisms.
• They speed up biochemical reactions by lowering the activation energy required for the reaction to occur.
• Enzymes are typically made up of proteins, though some RNA molecules can also function as enzymes (e.g., ribozymes).
• Each enzyme is highly specific to the substrate it acts upon due to the unique structure of its active site.
• They play a crucial role in various processes such as digestion, respiration, and DNA replication.
• Examples of enzymes include amylase (breaks down starch), lipase (breaks down fats), and protease (breaks down proteins).
• Enzymes are sensitive to environmental factors such as temperature and pH, which can affect their activity.

 Additional Information

• Hydrochloric acid
  • Hydrochloric acid (HCl) is a component of gastric juice in the stomach.
  • It helps in the digestion process by creating an acidic environment, which activates the enzyme pepsin for protein breakdown.
  • HCl also kills bacteria and other pathogens in the food.
• Mucus
  • Mucus is a slippery secretion produced by mucous membranes in the body.
  • It plays a role in protecting tissues, such as the lining of the stomach, from damage caused by digestive acids and enzymes.
  • Mucus also helps in lubricating food for easier swallowing and movement through the digestive system.
• Digestive juices
  • Digestive juices are fluids secreted by the digestive organs, including the stomach, pancreas, and intestines.
  • They contain enzymes, such as amylase, lipase, and protease, which help in breaking down carbohydrates, fats, and proteins, respectively.
  • While digestive juices aid digestion, they are not catalysts themselves; instead, they carry enzymes which perform catalytic functions.

The correct answer is Lipase.

Key Points

• Lipase enzymes are used in the stabilization of rice bran oil.
• Rice bran oil is known as wonder oil and it is the most important vegetable oil in Asia.
• Rice bran oil is extracted from bran which is the outer hard layer of rice.
• It is an emerging category in edible oil with a lot of nutritional properties and health benefits.
• Rice bran oil is heart-friendly, immunity, and prevents other diseases.
• The current study aimed to stabilize rice bran oil through different probiotic isolates and to assess the nutritional content of rice bran oil after stabilization.
• The study was aimed to inactivate naturally occurring lipases that can hydrolyze oil into glycerol and free fatty acid which is a serious problem that gives it a rancid taste and smell.

Additional Information

• Hydrolases are the group of enzymes that catalyze bond cleavages by reaction with water. The natural function of most hydrolases is digestion to break down nutrients into smaller units for digestion.
• Catalase is a key enzyme that uses hydrogen peroxide, a non-radical ROS, as its substrate. This enzyme is responsible for neutralization through the decomposition of hydrogen peroxide, thereby maintaining an optimum level of the molecule in the cell which is also essential for cellular signaling processes.
• Cellulase is any of several enzymes produced chiefly by fungi, bacteria, and protozoans that catalyze cellulolysis, the decomposition of cellulose and of some related polysaccharides. The name is also used for any naturally occurring mixture or complex of various such enzymes, that act serially or synergistically to decompose cellulosic material.

The correct answer is lysosomes.

Key Points

• Lysosomes
  • These are membrane bound vesicular structures formed by the process of packaging in the golgi apparatus.
  • The isolated lysosomal vesicles have been found to be very rich in almost all types of hydrolytic enzymes (hydrolases – lipases, proteases, carbohydrases) optimally active at the acidic pH.
    • These enzymes are capable of digesting carbohydrates, proteins, lipids, and nucleic acids.

Important Points

• Vacuoles
  • The vacuole is the membrane-bound space found in the cytoplasm.
  • It contains water, sap, excretory product and other materials not useful for the cell.
  • The vacuole is bound by a single membrane called tonoplast.
  • In plant cells, the vacuoles can occupy up to 90% of the volume of the cell.
• Mitochondria
  • It is sausage-shaped or cylindrical having a diameter of 0.2-1.0µm (average 0.5µm) and length 1.0-4.1µm.
  • It is called the powerhouse of the cell.
  • Each mitochondrion is a double membrane-bound structure with the outer membrane and the inner membrane dividing its lumen distinctly into two aqueous compartments.
    • The outer compartment and the inner compartment.
    • The inner compartment is filled with a dense homogeneous substance called the matrix.
    • The outer membrane forms the continuous limiting boundary of the organelle.
• Ribosomes
  • Ribosomes are made up of RNA and proteins. 
  • The ribosomes, which are present in all active cells, are the sites of protein manufacture.
  • In prokaryotes, ribosomes are associated with the plasma membrane of the cell.

The correct answer is Pepsin.

Key Points

• Pepsin is a protein-digesting enzyme.
• So, if the acid-secreting cells of the stomach wall get damaged due to some reasons, the digestion of protein would be affected to a large extent.
• Pepsin activation would be reduced resulting in low to no protein digestion.
• This may also lead to increased bacterial growth as a result of the non-production of HCl.

Important Points

• The Gastric Glands secrete the enzyme Pepsin.
• Gastric glands are found in the stomach. They secrete enzymes like Pepsin, Rennin which act upon the Proteins.
• Glands in the mucous membrane which line the stomach make and store an inactive protein known as pepsinogen. When pepsinogen is released into the stomach and mixed with gastric juice, it is converted into pepsin.
• Pepsin partially degrades proteins into smaller units called peptides.

Additional Information

• Salivary amylase is a digestive enzyme that helps in the breakdown of carbohydrates (starch) into simpler molecules.
• Collagen fiber is a type of connective tissue fiber.
  • It is made up of collagen protein.
  • It provides strength to the body in various ways.
• Lipase is an enzyme that splits fats so the intestines can absorb them.
  • Lipase hydrolyses fats like triglycerides into their component fatty acid and glycerol molecules.
  • It is secreted by Pancreas.

The correct answer is enzymes.

Key Points

• Enzymes are proteins that help speed up metabolism or the chemical reactions in our bodies.
• Enzymes present in our body help in digesting complex substances by breaking them down into simpler forms.
• They are produced naturally in the body and help with important tasks, including building muscle.
• Our bodies naturally produce both digestive and metabolic enzymes, according to the requirement.

Additional Information

• There are approximately 1300 different enzymes found in the human cell.
• Digestive enzymes can be obtained from supplements or naturally through foods like pineapples, papayas, mangoes, honey, bananas, and avocados.
• Different parts of our body contain and produce different enzymes like

The correct answer is Saliva.

Key Points

• Saliva contains an enzyme called Lingual Lipase, which helps in breaking down fats.
• Our saliva plays a significant role in our digestive system.
• It also contains enzymes like Amylase and Isozyme.
• Amylase breaks down starches (complex carbohydrates) into sugars, which can be absorbed more easily by our body.

Additional Information

• Saliva is an aqueous fluid found in the oral cavity playing a fundamental role in the preservation and maintenance of oral health. Saliva acts in relation to taste, mastication, bolus formation, enzymatic digestion, and swallowing.
• Enzymes are proteins that help speed up metabolism, or the chemical reactions in our bodies.
• These are some important enzymes needed for our digestion

The correct answer is Valine is a non-essential amino acid, and it is synthesized in the human body.

Key Points

• The amino acids which the body cannot synthesize are called essential amino acids.
• Essential amino acids are those amino acids that are not produced by our body, they have to be taken through the food we eat.
• Valine is an essential amino acid. Therefore Statement 3 is false.
• Essential amino acids cannot be made by the body so you must get them from your diet.
• Histidine is an essential amino acid, which means it is necessary for growth and tissue repair.
• Histidine is involved in the production of histamine, a neurotransmitter that is important for immune response and digestion.
• Lysine is also an essential amino acid that plays a role in protein synthesis, collagen formation, and the absorption of calcium. 

Additional Information

• There are 9 essential amino acids valine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, and tryptophan.

The correct answer is Fatty acids and Glycerol.

Key Points

• Enzymes are proteinaceous.
• It breaks down the biomolecules into a simple absorbable form.
• The pancreatic gland releases lipase.
• Fatty acid and glycerol are obtained by the aqueous decomposition of fat by lipase.
• In the small intestinal, it helps break the bonds and release fatty acid and glycerol.
• Fat molecules consist of 3 fatty acid and glycerol molecules.
• Fat is stored in adipocytes.
• Adipocytes are cells found in adipose tissue.
• The fat is used as body fuel and provides energy for the body's metabolic reactions.

Additional Information 

Glucose:

• Glucose is the main type of sugar present in human blood.
• Glucose came to the human body through food and provides energy to the body
• It is aldose sugar.
• It is 6-carbon sugar.
• It provides energy to the cell.

Amino acids:

• Amino acids are the building blocks of proteins.
• Proteins and amino acids are the components of life.
• Amino acids are the byproducts of the digestion or breakdown of proteins.
• Essential amino acids are those that our body cannot make on its own and must be obtained from our diet.
• The 9 essential amino acids are:
  • Histidine.
  • Isoleucine.
  • Leucine.
  • Lysine.
  • Methionine.
  • Phenylalanine.
  • Threonine.
  • Tryptophan.
  • Valine.

Alkaloid:

• An alkaloid is a class of naturally occurring organic nitrogen-containing compounds that are frequently found in the plant kingdom.
• Many alkaloids are valuable medicinal agents that can be utilized to treat various diseases including malaria, diabetes, cancer, cardiac dysfunction, etc.

The correct answer is option 2, i.e. Pancreas.

• Lipase is an enzyme that splits fats so the intestines can absorb them.
• Lipase hydrolyses fats like triglycerides into their component fatty acid and glycerol molecules.
• It is secreted by Pancreas.
• Pancreas is a composite gland which acts as both exocrine glands (contains exocrine cells ) and endocrine gland(contains endocrine cells).
  • Endocrine glands secrete chemical substances into the bloodstream or tissues of the body.
  • Exocrine glands secrete substances onto an epithelial surface by way of a duct.

The correct answer is saliva.

Key Points

• Amylase:
  • Amylase is defined as a digestive enzyme that breaks starch into small carbohydrate molecules.
  • Amylase is found in the saliva of humans.
  • This enzyme is produced in two areas. Firstly, salivary glands in our mouth generate salivary amylase that starts the process of digestion by breaking down starch and converting it into maltose and smaller carbohydrate.
  • Cells in the pancreas also produce a different type of amylase, known as pancreatic amylase that travels via a duct to reach the small intestine.
  • Pancreatic amylase finishes the digestion of carbohydrates, producing glucose.
  • Amylase is found to be stable over a wide range of pH values (5.0 to 10.5) with an optimal pH for the enzymatic activity of 7.0.

Additional Information

• Enzymes:​
  • Enzymes are proteins made from amino acids.
  • It is made up of hundreds and thousands of amino acids stringed together in a very specific and unique order. 
  • Digestive enzymes are the enzymes that break down polymeric macromolecules into smaller building blocks to facilitate their absorption by the body.

The correct answer is Amino acids.

• Enzymes are made up of Amino acids.

Key Points

• Enzymes are made of chains of amino acids chemically bonded to one another.
  • These bonds give the enzyme a unique structure, which determines its function. 
• Enzymes help in processes like digestion, blood clotting, and hormone production. 
• They either catalyze or speed up chemical reactions that take place in the bodies of living things.
• Types of enzymes in the human body:
  • Lactase
  • Pectinase.
  • Bromelain
  • Papain
  • Catalase

Additional Information

• Carbohydrates are organic compounds in which the ratio of Carbon, Hydrogen and Oxygen is 1: 2: 1.
  • ​Carbohydrate works as fuel during the process of respiration, glucose break into CO₂ and H₂O with the release of energy.
  • One gram of glucose gives 4.2 kilocalories energy.
• Nucleic acids are polymers of nucleosides and nucleotides and contain pentose sugar.
• Fat is an ester of glycerol and fatty acid.
  • Normally fat remains as solid at 20°C temperature, but if it is in liquid form at this temperature, this is called oil.
  • 9.3 kilocalorie energy is liberated from 1 gram fat.