MCQ on Carbohydrates - Biology Ease

🟢 Easy Level (1–20)

Which of the following is a carbohydrate?
A) Starch ✅
B) Protein
C) Fat
D) DNA
Explanation: Starch is a polysaccharide and a storage form of carbohydrate in plants.
What are the building blocks of carbohydrates?
A) Amino acids
B) Fatty acids
C) Monosaccharides ✅
D) Nucleotides
Explanation: Monosaccharides like glucose are the basic units of carbohydrates.
Which of these is a monosaccharide?
A) Lactose
B) Sucrose
C) Glucose ✅
D) Starch
Explanation: Glucose is a single sugar unit, a monosaccharide.
What is the main function of carbohydrates?
A) Enzyme production
B) Genetic coding
C) Energy supply ✅
D) Hormone synthesis
Explanation: Carbohydrates are the body’s primary energy source.
Which carbohydrate is commonly called “blood sugar”?
A) Fructose
B) Galactose
C) Glucose ✅
D) Maltose
Explanation: Glucose circulates in the blood and is used for energy.
Sucrose is made of which two sugars?
A) Glucose + Galactose
B) Glucose + Fructose ✅
C) Glucose + Glucose
D) Fructose + Galactose
Explanation: Sucrose is a disaccharide of glucose and fructose.
Which of the following is a polysaccharide?
A) Glucose
B) Fructose
C) Cellulose ✅
D) Sucrose
Explanation: Cellulose is a complex carbohydrate made of many glucose units.
Which sugar is found in milk?
A) Fructose
B) Lactose ✅
C) Sucrose
D) Maltose
Explanation: Lactose is a disaccharide found in milk.
Which carbohydrate cannot be digested by humans?
A) Starch
B) Cellulose ✅
C) Glycogen
D) Maltose
Explanation: Humans lack enzymes to digest cellulose.
Which of the following is a storage carbohydrate in animals?
A) Glycogen ✅
B) Cellulose
C) Starch
D) Maltose
Explanation: Glycogen is stored in liver and muscles for energy.
Which organ stores the most glycogen?
A) Brain
B) Liver ✅
C) Kidney
D) Stomach
Explanation: The liver stores glycogen to maintain blood sugar levels.
Which enzyme breaks down starch in the mouth?
A) Lipase
B) Maltase
C) Amylase ✅
D) Lactase
Explanation: Salivary amylase starts starch digestion in the mouth.
The general formula for carbohydrates is:
A) CnH2nOn ✅
B) CnH2n+2
C) CH3COOH
D) CnH2n-1On
Explanation: Carbohydrates follow the general formula CnH2nOn.
Which of these is a reducing sugar?
A) Sucrose
B) Glucose ✅
C) Starch
D) Cellulose
Explanation: Glucose contains a free aldehyde group making it reducing.
Which test is used to detect reducing sugars?
A) Benedict’s test ✅
B) Biuret test
C) Sudan III test
D) Iodine test
Explanation: Benedict’s solution detects reducing sugars like glucose.
Which disaccharide is non-reducing?
A) Maltose
B) Lactose
C) Sucrose ✅
D) Glucose
Explanation: Sucrose does not have a free aldehyde or ketone group.
Fructose is commonly found in:
A) Dairy
B) Vegetables
C) Fruits ✅
D) Grains
Explanation: Fructose is the main sugar in fruits.
Carbohydrates are mainly absorbed in:
A) Mouth
B) Stomach
C) Small intestine ✅
D) Large intestine
Explanation: The small intestine absorbs most digested carbohydrates.
Which of the following is a hexose sugar?
A) Ribose
B) Glucose ✅
C) Deoxyribose
D) Fructose
Explanation: Glucose has six carbon atoms, making it a hexose.
Which is the sweetest natural sugar?
A) Glucose
B) Fructose ✅
C) Sucrose
D) Lactose
Explanation: Fructose is sweeter than other natural sugars.

🟡 Moderate Level (21–40)

Which enzyme breaks down lactose?
A) Maltase
B) Sucrase
C) Lactase ✅
D) Amylase
Explanation: Lactase breaks lactose into glucose and galactose.
Which of these carbohydrates is found in plant cell walls?
A) Glycogen
B) Cellulose ✅
C) Sucrose
D) Glucose
Explanation: Cellulose forms structural support in plant cell walls.
Which of the following has alpha-1,4 glycosidic bonds?
A) Cellulose
B) Starch ✅
C) Chitin
D) Lactose
Explanation: Starch consists of alpha-1,4 linked glucose units.
Chitin is a structural carbohydrate found in:
A) Fungi and arthropods ✅
B) Plants
C) Bacteria
D) Mammals
Explanation: Chitin forms exoskeletons in arthropods and walls in fungi.
Which is an example of a ketose sugar?
A) Glucose
B) Fructose ✅
C) Galactose
D) Maltose
Explanation: Fructose contains a ketone group.
Which bond connects two monosaccharides?
A) Peptide bond
B) Ester bond
C) Glycosidic bond ✅
D) Hydrogen bond
Explanation: Glycosidic bonds form between sugar molecules.
Which carbohydrate gives a positive iodine test?
A) Cellulose
B) Starch ✅
C) Glucose
D) Fructose
Explanation: Iodine turns blue-black in presence of starch.
Which form of starch is highly branched?
A) Amylose
B) Amylopectin ✅
C) Cellulose
D) Glycogen
Explanation: Amylopectin has branched chains of glucose.
What is the main difference between cellulose and starch?
A) Type of sugar
B) Glycosidic bond ✅
C) Molecular weight
D) Number of units
Explanation: Starch has alpha bonds, cellulose has beta bonds.
The storage form of carbohydrates in plants is:
A) Glycogen
B) Sucrose
C) Cellulose
D) Starch ✅
Explanation: Plants store glucose as starch.
The term “saccharide” refers to:
A) Proteins
B) Sugars ✅
C) Fats
D) Hormones
Explanation: Saccharides are sugar molecules—mono-, di-, or polysaccharides.
Which of the following is a trisaccharide?
A) Raffinose ✅
B) Glucose
C) Lactose
D) Sucrose
Explanation: Raffinose is composed of three monosaccharides.
The glycemic index measures:
A) Fat content
B) Vitamin level
C) Effect of carbohydrate on blood glucose ✅
D) Fiber content
Explanation: It ranks carbs based on their impact on blood sugar.
Which carbohydrate helps in cell signaling?
A) Glycogen
B) Glycoproteins ✅
C) Cellulose
D) Maltose
Explanation: Glycoproteins play roles in cell recognition and communication.
In humans, excess glucose is stored as:
A) Starch
B) Glycogen ✅
C) Lactose
D) Sucrose
Explanation: Glucose is converted to glycogen for storage.
Which polysaccharide is used in bacterial cell walls?
A) Glycogen
B) Peptidoglycan ✅
C) Cellulose
D) Chitin
Explanation: Peptidoglycan is a structural component in bacteria.
Which of the following carbohydrates is found in DNA?
A) Ribose
B) Deoxyribose ✅
C) Glucose
D) Fructose
Explanation: DNA contains deoxyribose sugar.
Which sugar is the sweetest?
A) Maltose
B) Fructose ✅
C) Glucose
D) Sucrose
Explanation: Fructose is naturally the sweetest carbohydrate.
Which sugar is used in intravenous therapy?
A) Lactose
B) Fructose
C) Glucose ✅
D) Sucrose
Explanation: Glucose is administered in IV fluids for energy.
The functional group in glucose includes:
A) Ketone
B) Aldehyde ✅
C) Amine
D) Carboxyl
Explanation: Glucose contains an aldehyde group, making it an aldose.

🔴 Hard Level (41–50)

Which of the following is a non-reducing sugar?
A) Glucose
B) Fructose
C) Sucrose ✅
D) Maltose
Explanation: Sucrose lacks a free aldehyde/ketone group.
Beta-glycosidic bonds are found in:
A) Glycogen
B) Amylose
C) Cellulose ✅
D) Maltose
Explanation: Cellulose consists of β-1,4 glycosidic bonds.
Which sugar alcohol is used in sugar-free products?
A) Lactose
B) Sorbitol ✅
C) Sucrose
D) Glucose
Explanation: Sorbitol is a sugar alcohol used in low-calorie foods.
Glycogen is structurally similar to:
A) Amylose
B) Cellulose
C) Amylopectin ✅
D) Raffinose
Explanation: Both glycogen and amylopectin are branched polymers.
Which test identifies starch?
A) Fehling’s test
B) Iodine test ✅
C) Benedict’s test
D) Biuret test
Explanation: Iodine binds with starch, giving a blue-black color.
Lactose intolerance results from lack of:
A) Glucose
B) Lactase ✅
C) Amylase
D) Sucrase
Explanation: Lactase deficiency causes lactose intolerance.
The cyclic form of glucose is called:
A) Hemiketal
B) Hemiacetal ✅
C) Ketose
D) Anomer
Explanation: The cyclic glucose forms a hemiacetal structure.
Which enzyme catalyzes glycogen breakdown?
A) Glycogen synthase
B) Amylase
C) Glycogen phosphorylase ✅
D) Maltase
Explanation: Glycogen phosphorylase breaks glycogen into glucose-1-phosphate.
What is the carbon number in fructose?
A) 4
B) 5
C) 6 ✅
D) 7
Explanation: Fructose is a 6-carbon ketose sugar.
Which vitamin is required for carbohydrate metabolism?
A) Vitamin C
B) Vitamin D
C) Thiamine (B1) ✅
D) Vitamin K
Explanation: Thiamine is essential for carbohydrate enzymatic reactions.

🟢 Easy Level (1–20)

🟡 Moderate Level (21–40)

🔴 Hard Level (41–50)

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