Enzymes
PYQ-Based Questions (Q1–10)
-
Enzymes are: (BPSC 64th Prelims)
a) Fats
b) Proteins
c) Carbohydrates
d) Vitamins
Answer: b
Explanation: Most enzymes are proteins that catalyze biochemical reactions. -
The function of enzymes in the human body is: (BPSC 63rd Prelims)
a) Hormone production
b) Increase body temperature
c) Catalyze chemical reactions
d) Destroy harmful bacteria
Answer: c
Explanation: Enzymes act as biological catalysts that speed up chemical reactions. -
Which enzyme converts starch into sugar? (BPSC 66th Prelims)
a) Pepsin
b) Maltase
c) Amylase
d) Lipase
Answer: c
Explanation: Amylase breaks down starch into simple sugars like maltose and glucose. -
Which of the following enzymes is present in saliva? (UPSC Prelims 2012)
a) Lipase
b) Trypsin
c) Amylase
d) Pepsin
Answer: c
Explanation: Saliva contains salivary amylase (ptyalin), which digests starch. -
Which of the following is not an enzyme? (BPSC 67th Prelims)
a) Rennin
b) Insulin
c) Trypsin
d) Pepsin
Answer: b
Explanation: Insulin is a hormone, not an enzyme. -
Which enzyme is secreted by the stomach? (BPSC 68th Prelims)
a) Amylase
b) Trypsin
c) Pepsin
d) Lipase
Answer: c
Explanation: Pepsin is a proteolytic enzyme secreted in the stomach for protein digestion. -
The enzyme lipase acts on: (UPSC Prelims 2014)
a) Proteins
b) Carbohydrates
c) Fats
d) Vitamins
Answer: c
Explanation: Lipase helps break down fats into fatty acids and glycerol. -
Enzymes are destroyed at: (BPSC 65th Prelims)
a) High pressure
b) Low temperature
c) Very high temperature
d) pH 7
Answer: c
Explanation: High temperatures can denature enzymes and destroy their catalytic activity. -
Which of the following enzymes is involved in digestion of proteins? (UPPSC 2016)
a) Lipase
b) Pepsin
c) Amylase
d) Lactase
Answer: b
Explanation: Pepsin is a protease enzyme that breaks proteins into smaller peptides. -
The activity of enzymes is affected by: (BPSC 60–62nd Prelims)
a) Temperature
b) pH
c) Concentration
d) All of the above
Answer: d
Explanation: Enzyme activity is influenced by temperature, pH, and substrate concentration.
NCERT-Based Questions (Q11–30)
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Enzymes increase the rate of a reaction by:
a) Raising the temperature
b) Lowering activation energy
c) Increasing product concentration
d) Providing energy
Answer: b
Explanation: Enzymes lower the activation energy needed for a reaction to occur. -
Which of the following is an example of a coenzyme?
a) NaCl
b) HCl
c) NAD⁺
d) O₂
Answer: c
Explanation: NAD⁺ is a coenzyme that helps dehydrogenase enzymes in redox reactions. -
The substrate binds to the enzyme at the:
a) Active site
b) Allosteric site
c) Reaction site
d) Receptor site
Answer: a
Explanation: Substrates fit into the enzyme's active site like a key in a lock. -
Enzymes are specific because of their:
a) Size
b) Shape
c) pH
d) Ionic nature
Answer: b
Explanation: The three-dimensional shape of an enzyme determines its specificity. -
Which enzyme breaks down milk sugar (lactose)?
a) Amylase
b) Lactase
c) Maltase
d) Lipase
Answer: b
Explanation: Lactase digests lactose into glucose and galactose. -
Which enzyme is found in gastric juice?
a) Amylase
b) Pepsin
c) Trypsin
d) Lipase
Answer: b
Explanation: Gastric juice contains pepsin for protein digestion. -
Enzymes act as:
a) Substrates
b) Products
c) Catalysts
d) Inhibitors
Answer: c
Explanation: Enzymes are biological catalysts that speed up reactions without being consumed. -
Which enzyme helps in the digestion of fat?
a) Pepsin
b) Amylase
c) Lipase
d) Rennin
Answer: c
Explanation: Lipase breaks fats into fatty acids and glycerol. -
The optimal temperature for most human enzymes is around:
a) 10°C
b) 25°C
c) 37°C
d) 100°C
Answer: c
Explanation: Human enzymes work best at body temperature, about 37°C. -
Which of the following is a characteristic of enzymes?
a) They are used up in reactions
b) They work slowly
c) They are highly specific
d) They are inorganic
Answer: c
Explanation: Enzymes are highly specific to the reactions they catalyze. -
Pepsin functions best at:
a) Neutral pH
b) Alkaline pH
c) Acidic pH
d) pH 7.8
Answer: c
Explanation: Pepsin works in the acidic environment of the stomach (around pH 2). -
Enzyme activity stops when the enzyme:
a) Denatures
b) Activates
c) Is diluted
d) Replicates
Answer: a
Explanation: Denaturation changes the enzyme's shape and renders it inactive. -
Which vitamin is part of the coenzyme NAD?
a) Vitamin A
b) Vitamin B3
c) Vitamin C
d) Vitamin D
Answer: b
Explanation: Vitamin B3 (niacin) is a component of NAD. -
Enzymes are produced by:
a) Golgi bodies
b) Ribosomes
c) Lysosomes
d) Vacuoles
Answer: b
Explanation: Ribosomes synthesize proteins, including enzymes. -
The enzyme trypsin acts in:
a) Stomach
b) Mouth
c) Small intestine
d) Large intestine
Answer: c
Explanation: Trypsin is active in the small intestine and digests proteins. -
Inhibitors that bind to the active site are called:
a) Non-competitive inhibitors
b) Catalysts
c) Competitive inhibitors
d) Substrates
Answer: c
Explanation: Competitive inhibitors compete with the substrate for the enzyme’s active site. -
Which of the following enzymes is secreted in an inactive form?
a) Trypsin
b) Amylase
c) Maltase
d) Lactase
Answer: a
Explanation: Trypsin is secreted as trypsinogen to avoid damage to the pancreas. -
Zymogen is another term for:
a) Substrate
b) Active enzyme
c) Inactive enzyme
d) Product
Answer: c
Explanation: Zymogens are inactive precursors of enzymes. -
Catalase breaks down:
a) Oxygen
b) Water
c) Hydrogen peroxide
d) Carbon dioxide
Answer: c
Explanation: Catalase decomposes hydrogen peroxide into water and oxygen. -
Which enzyme is deficient in lactose intolerance?
a) Maltase
b) Sucrase
c) Lactase
d) Pepsin
Answer: c
Explanation: Lactose-intolerant individuals lack sufficient lactase enzyme.
Predicted/Reference Book-Based Questions (Q31–50)
-
The term "enzyme" was coined by:
a) Pasteur
b) Buchner
c) Kuhne
d) Tswett
Answer: c
Explanation: Wilhelm Kuhne coined the term "enzyme" in 1878. -
Enzymes are chemically:
a) Fats
b) Vitamins
c) Proteins
d) Carbohydrates
Answer: c
Explanation: All enzymes are proteins, although some RNA molecules also have catalytic properties. -
The enzyme used in the breakdown of urea is:
a) Urease
b) Maltase
c) Amylase
d) Pepsin
Answer: a
Explanation: Urease catalyzes the conversion of urea to ammonia and carbon dioxide. -
Which organ secretes most digestive enzymes?
a) Liver
b) Pancreas
c) Gallbladder
d) Kidney
Answer: b
Explanation: The pancreas secretes enzymes for digestion of carbohydrates, fats, and proteins. -
The enzyme that acts in the acidic medium is:
a) Amylase
b) Pepsin
c) Trypsin
d) Lipase
Answer: b
Explanation: Pepsin functions in the acidic pH of the stomach. -
Lysozyme is found in:
a) Blood
b) Liver
c) Saliva
d) Tears
Answer: d
Explanation: Lysozyme is an antibacterial enzyme found in tears and saliva. -
Enzymes catalyze reactions by forming a:
a) Complex with DNA
b) Substrate-enzyme complex
c) Product chain
d) Catalyst-substrate mixture
Answer: b
Explanation: Enzymes temporarily bind substrates to form an enzyme-substrate complex. -
The enzyme that converts glucose to glucose-6-phosphate is:
a) Hexokinase
b) Amylase
c) Maltase
d) Lipase
Answer: a
Explanation: Hexokinase phosphorylates glucose during glycolysis. -
Which of these is a digestive enzyme?
a) Hemoglobin
b) Amylase
c) Insulin
d) Myosin
Answer: b
Explanation: Amylase digests starch in the mouth and small intestine. -
Enzyme activity is measured in terms of:
a) pH
b) Molecular weight
c) Turnover number
d) Viscosity
Answer: c
Explanation: Turnover number refers to the number of substrate molecules converted per second. -
Which enzyme digests milk proteins in infants?
a) Lipase
b) Pepsin
c) Rennin
d) Amylase
Answer: c
Explanation: Rennin (chymosin) curdles milk proteins in infants. -
Enzyme used in making alcohol from sugar is:
a) Amylase
b) Zymase
c) Pepsin
d) Maltase
Answer: b
Explanation: Zymase is a complex of enzymes that ferments sugar to alcohol. -
Which enzyme is used in the manufacture of cheese?
a) Amylase
b) Pepsin
c) Lipase
d) Rennin
Answer: d
Explanation: Rennin is used to coagulate milk in cheese-making. -
Which enzyme converts glucose to alcohol?
a) Invertase
b) Zymase
c) Diastase
d) Lipase
Answer: b
Explanation: Zymase catalyzes fermentation of glucose to ethanol and carbon dioxide. -
Which of the following is a hydrolytic enzyme?
a) Dehydrogenase
b) Ligase
c) Lipase
d) Synthase
Answer: c
Explanation: Lipase catalyzes hydrolysis of fats into glycerol and fatty acids. -
The enzyme invertase acts on:
a) Lactose
b) Maltose
c) Sucrose
d) Glucose
Answer: c
Explanation: Invertase splits sucrose into glucose and fructose. -
Thermolabile enzymes are:
a) Stable at high temperature
b) Inactive at low temperature
c) Destroyed at high temperature
d) Activated at freezing point
Answer: c
Explanation: Thermolabile enzymes are heat-sensitive and become inactive at high temperatures. -
Which enzyme is used in DNA replication?
a) Pepsin
b) DNA polymerase
c) Lipase
d) Urease
Answer: b
Explanation: DNA polymerase synthesizes new DNA strands during replication. -
Which of the following affects enzyme action?
a) Temperature
b) pH
c) Substrate concentration
d) All of these
Answer: d
Explanation: Enzyme activity is influenced by several factors including pH, temperature, and substrate levels. -
Enzymes remain unchanged:
a) Before the reaction
b) During the reaction
c) After the reaction
d) All of the above
Answer: c
Explanation: Enzymes are not consumed or permanently altered in the reactions they catalyze.