MCQ 1
Statement: What is the primary function of carbohydrates?
Options:
a) Provide energy
b) Act as enzymes
c) Regulate processes
d) Make membranes
Answer: a) Provide energy
Explanation: Carbohydrates are the body’s main source of energy. They are broken down into glucose, which is used by cells for metabolic activities.
Tips and Tricks:
- Remember: “Carbs = Energy.”
- Enzymes are proteins, not carbohydrates.
MCQ 2
Statement: How will you differentiate between monosaccharides and polysaccharides?
Options:
a) Monosaccharides are single sugars.
b) Polysaccharides are sweet in taste.
c) Monosaccharides are present in plant cell walls.
d) Polysaccharides dissolve easily.
Answer: a) Monosaccharides are single sugars.
Explanation: Monosaccharides (like glucose) are simple sugars, while polysaccharides (like starch) are complex carbohydrates made of many monosaccharide units.
Tips and Tricks:
- Mono = one (single sugar); Poly = many (complex sugars).
- Polysaccharides are not usually sweet.
MCQ 3
Statement: What is true about cellulose?
Options:
a) It is sweet in taste.
b) It is digestible by the human digestive system.
c) It provides structural support in plants.
d) It is soluble in water.
Answer: c) It provides structural support in plants.
Explanation: Cellulose is a polysaccharide that forms the cell walls in plants, providing structural strength. Humans cannot digest cellulose due to a lack of the enzyme cellulase.
Tips and Tricks:
- Remember cellulose as the “building block” of plant cell walls.
- It is insoluble in water and not sweet.
MCQ 4
Statement: Which of the following proteins is involved in oxygen transport?
Options:
a) Collagen
b) Hemoglobin
c) Keratin
d) Myosin
Answer: b) Hemoglobin
Explanation: Hemoglobin is a protein found in red blood cells responsible for transporting oxygen from the lungs to body tissues and carrying carbon dioxide back to the lungs.
Tips and Tricks:
- Think of “Hemoglobin = Oxygen transporter.”
- Collagen supports structure, keratin strengthens skin and hair, and myosin aids in muscle contraction.
MCQ 5
Statement: Which component of an amino acid determines its unique properties?
Options:
a) Amino group
b) Carboxyl group
c) R group (side chain)
d) Hydrogen group
Answer: c) R group (side chain)
Explanation: The R group (side chain) varies among amino acids and determines their unique chemical properties, such as polarity, charge, and hydrophobicity.
Tips and Tricks:
- Remember: “R group = unique.” The amino and carboxyl groups are the same in all amino acids.
MCQ 6
Statement: Which proteins are involved in defense against pathogens?
Options:
a) Myosin
b) Hemoglobin
c) Antibodies
d) Fibrinogen
Answer: c) Antibodies
Explanation: Antibodies are proteins produced by the immune system that recognize and neutralize pathogens like bacteria and viruses.
Tips and Tricks:
- Antibodies = “Defenders” in the immune system.
- Myosin aids in movement, hemoglobin in oxygen transport, and fibrinogen in blood clotting.
MCQ 7
Statement: Which of the following is the basic structural unit of most lipids?
Options:
a) Nucleotides
b) Fatty acids and glycerol
c) Simple sugars
d) Amino acids
Answer: b) Fatty acids and glycerol
Explanation: Lipids are composed of glycerol and fatty acids. Glycerol serves as the backbone, while fatty acids provide hydrophobic tails.
Tips and Tricks:
- Lipids = “Fatty acids + Glycerol.”
- Nucleotides form DNA/RNA, amino acids make proteins, and simple sugars form carbohydrates.
MCQ 8
Statement: How do unsaturated fatty acids differ from saturated fatty acids?
Options:
a) They have more hydrogen atoms.
b) They contain double bonds in their hydrocarbon chains.
c) They are solid at room temperature.
d) They are found only in animal fats.
Answer: b) They contain double bonds in their hydrocarbon chains.
Explanation: Unsaturated fatty acids have one or more double bonds in their carbon chain, making them liquid at room temperature (e.g., oils). Saturated fatty acids lack double bonds and are solid at room temperature (e.g., butter).
Tips and Tricks:
- Unsaturated = Double bonds = Liquid (Oils).
- Saturated = Single bonds = Solid (Butter).
MCQ 9:
Statement: Which of the following is NOT a function of proteins?
Options:
a) Transport oxygen in the blood
b) Carry genetic information
c) Help in digesting food
d) Fight against infections
Answer: b) Carry genetic information
Explanation: Proteins are responsible for functions like oxygen transport (e.g., hemoglobin), digestion (e.g., enzymes), and immunity (e.g., antibodies). Genetic information is carried by nucleic acids (DNA and RNA), not proteins.
Tips and Tricks:
- Remember: “Proteins = Functional workers” and “DNA/RNA = Genetic storage.”
MCQ 10:
Statement: Which component makes up a nucleotide?
Options:
a) Amino acid, phosphate, nitrogenous base
b) Sugar, phosphate, nitrogenous base
c) Fatty acid, nitrogenous base, sugar
d) Protein, sugar, phosphate
Answer: b) Sugar, phosphate, nitrogenous base
Explanation: A nucleotide, the building block of DNA/RNA, consists of a pentose sugar (deoxyribose or ribose), a phosphate group, and a nitrogenous base (A, T, C, G, or U).
Tips and Tricks:
- Remember the “S-P-B” structure: Sugar-Phosphate-Base.
MCQ 11:
Statement: Which nitrogenous base is found in RNA but not in DNA?
Options:
a) Adenine
b) Uracil
c) Thymine
d) Guanine
Answer: b) Uracil
Explanation: RNA contains uracil instead of thymine, which is found in DNA. Both uracil and thymine pair with adenine during transcription or replication.
Tips and Tricks:
- Remember: “DNA = Thymine (T),” “RNA = Uracil (U).”
Short Questions with Answers
- What are the main functions of carbohydrates in the body?
Answer:- Provide energy (e.g., glucose for cellular respiration).
- Serve as storage (e.g., glycogen in animals, starch in plants).
- Form structural components (e.g., cellulose in plants).
- Write the general formula of carbohydrates and give two examples of monosaccharides.
Answer:- General formula: Cn(H2O)nC_n(H_2O)_n
- Examples: Glucose and fructose.
- Name one polysaccharide found in plants and one in animals.
Answer:- Plants: Starch
- Animals: Glycogen
- What is the difference between a nucleotide and a nucleoside?
Answer:- Nucleotide: Composed of a sugar, phosphate, and nitrogenous base.
- Nucleoside: Composed of a sugar and nitrogenous base only (no phosphate).
- Name the two types of nucleic acids and describe their functions.
Answer:- DNA (Deoxyribonucleic acid): Stores genetic information.
- RNA (Ribonucleic acid): Assists in protein synthesis and carries genetic messages.
- Differentiate between saturated and unsaturated fatty acids.
Answer:- Saturated fatty acids: Contain no double bonds, solid at room temperature (e.g., butter).
- Unsaturated fatty acids: Contain one or more double bonds, liquid at room temperature (e.g., olive oil).
Long Questions with Answers
1. Discuss the levels of molecular biology.
Answer:
- Nucleotides and nucleic acids:
- Nucleotides form nucleic acids like DNA and RNA, which store and transmit genetic information.
- Proteins:
- Made up of amino acids, proteins perform diverse biological functions like catalysis (enzymes), structure (collagen), and transport (hemoglobin).
- Carbohydrates and lipids:
- Carbohydrates provide energy, while lipids are essential for energy storage, insulation, and forming cell membranes.
2. Differentiate between DNA and RNA.
Answer:
| Feature | DNA | RNA |
|---|---|---|
| Sugar | Deoxyribose | Ribose |
| Strands | Double-stranded | Single-stranded |
| Bases | A, T, G, C | A, U, G, C |
| Function | Stores genetic information | Helps in protein synthesis |
3. What are saturated and unsaturated fatty acids? Give their functions.
Answer:
- Saturated fatty acids:
- No double bonds between carbon atoms.
- Solid at room temperature (e.g., animal fats).
- Function: Provide long-term energy storage.
- Unsaturated fatty acids:
- Contain one or more double bonds.
- Liquid at room temperature (e.g., vegetable oils).
- Function: Maintain membrane fluidity and support heart health.
4. Write a note on lipids.
Answer:
- Definition: Lipids are hydrophobic molecules that include fats, oils, and steroids.
- Structure: Composed of glycerol and fatty acids.
- Functions:
- Long-term energy storage.
- Insulation and protection.
- Forming cell membranes (phospholipids).
5. Explain the double-helix structure of DNA and discuss the base pairing in DNA.
Answer:
- Double-helix structure: DNA is a spiral-shaped molecule made of two strands twisted around each other, held together by hydrogen bonds.
- Base pairing:
- Adenine (A) pairs with Thymine (T).
- Cytosine (C) pairs with Guanine (G).
- Base pairing follows the complementary rule (A-T, C-G).
- Significance: Base pairing ensures accurate replication and transcription of genetic information.
