Q.1 What is the basic building block of proteins?
Monosaccharides
Amino acids
Fatty acids
Nucleotides
Explanation - Proteins are polymers made of amino acids linked together by peptide bonds.
Correct answer is: Amino acids
Q.2 Which of the following is a monosaccharide?
Sucrose
Glucose
Starch
Cellulose
Explanation - Glucose is a simple sugar, a monosaccharide, whereas sucrose, starch, and cellulose are polysaccharides or disaccharides.
Correct answer is: Glucose
Q.3 Which bond connects nucleotides in DNA?
Peptide bond
Glycosidic bond
Phosphodiester bond
Hydrogen bond
Explanation - Nucleotides in DNA are linked via phosphodiester bonds between the phosphate group of one nucleotide and the sugar of the next.
Correct answer is: Phosphodiester bond
Q.4 Which macromolecule serves as the primary energy source for cells?
Proteins
Lipids
Carbohydrates
Nucleic acids
Explanation - Carbohydrates are the main energy source for cells because they are easily metabolized to release energy.
Correct answer is: Carbohydrates
Q.5 Which vitamin is water-soluble?
Vitamin A
Vitamin D
Vitamin C
Vitamin E
Explanation - Vitamin C is water-soluble, whereas vitamins A, D, and E are fat-soluble.
Correct answer is: Vitamin C
Q.6 Which element is central to organic molecules?
Oxygen
Carbon
Nitrogen
Hydrogen
Explanation - Carbon is the central element of organic molecules due to its ability to form four covalent bonds.
Correct answer is: Carbon
Q.7 What is the storage form of glucose in animals?
Cellulose
Starch
Glycogen
Chitin
Explanation - Glycogen is the polysaccharide used for energy storage in animals, primarily in liver and muscles.
Correct answer is: Glycogen
Q.8 Which functional group is found in all amino acids?
Hydroxyl group
Carboxyl group
Aldehyde group
Ketone group
Explanation - All amino acids contain a carboxyl (-COOH) group and an amino (-NH2) group.
Correct answer is: Carboxyl group
Q.9 Enzymes are primarily made of which macromolecule?
Lipids
Proteins
Carbohydrates
Nucleic acids
Explanation - Most enzymes are proteins that act as biological catalysts, increasing reaction rates.
Correct answer is: Proteins
Q.10 Which lipid is most abundant in the plasma membrane?
Triglycerides
Phospholipids
Steroids
Waxes
Explanation - Phospholipids form the bilayer of plasma membranes, providing structural integrity and fluidity.
Correct answer is: Phospholipids
Q.11 Which nucleic acid is responsible for protein synthesis?
DNA
mRNA
tRNA
Both mRNA and tRNA
Explanation - mRNA carries the genetic code, and tRNA brings amino acids during translation, both essential for protein synthesis.
Correct answer is: Both mRNA and tRNA
Q.12 Which type of bond stabilizes the secondary structure of proteins?
Hydrogen bond
Ionic bond
Peptide bond
Disulfide bond
Explanation - Hydrogen bonds between backbone atoms stabilize α-helices and β-sheets in proteins.
Correct answer is: Hydrogen bond
Q.13 Which sugar is found in RNA but not DNA?
Ribose
Deoxyribose
Glucose
Fructose
Explanation - RNA contains ribose sugar, whereas DNA contains deoxyribose.
Correct answer is: Ribose
Q.14 Which of the following is a purine base?
Cytosine
Thymine
Adenine
Uracil
Explanation - Adenine and guanine are purines, while cytosine, thymine, and uracil are pyrimidines.
Correct answer is: Adenine
Q.15 Which biomolecule has the highest energy content per gram?
Carbohydrates
Proteins
Lipids
Nucleic acids
Explanation - Lipids provide about 9 kcal/g, more than carbohydrates and proteins, which provide 4 kcal/g each.
Correct answer is: Lipids
Q.16 Which of the following is NOT a function of proteins?
Catalysis
Structural support
Information storage
Transport
Explanation - Proteins do not store genetic information; this is the role of nucleic acids.
Correct answer is: Information storage
Q.17 Which vitamin is essential for blood clotting?
Vitamin K
Vitamin B12
Vitamin C
Vitamin D
Explanation - Vitamin K is required for the synthesis of clotting factors in the liver.
Correct answer is: Vitamin K
Q.18 Which bond is responsible for tertiary protein structure?
Hydrogen bond
Ionic bond
Disulfide bond
All of the above
Explanation - Tertiary protein structure is stabilized by hydrogen bonds, ionic bonds, hydrophobic interactions, and disulfide bonds.
Correct answer is: All of the above
Q.19 Which coenzyme is derived from vitamin B3?
FAD
NAD+
CoA
Biotin
Explanation - NAD+ (Nicotinamide adenine dinucleotide) is derived from niacin (vitamin B3) and functions as an electron carrier.
Correct answer is: NAD+
Q.20 Which of the following is a disaccharide?
Glucose
Sucrose
Fructose
Galactose
Explanation - Sucrose is a disaccharide composed of glucose and fructose.
Correct answer is: Sucrose
Q.21 Which amino acid is sulfur-containing?
Serine
Cysteine
Leucine
Glycine
Explanation - Cysteine contains a thiol (-SH) group, making it a sulfur-containing amino acid.
Correct answer is: Cysteine
Q.22 Which type of RNA carries amino acids to ribosomes?
mRNA
tRNA
rRNA
snRNA
Explanation - Transfer RNA (tRNA) carries specific amino acids to the ribosome during protein synthesis.
Correct answer is: tRNA
Q.23 Which macromolecule can act as an enzyme?
Protein
Lipid
Carbohydrate
None of the above
Explanation - Most enzymes are proteins, although some RNA molecules (ribozymes) also have catalytic activity.
Correct answer is: Protein
Q.24 Which polysaccharide forms the exoskeleton of insects?
Cellulose
Chitin
Glycogen
Starch
Explanation - Chitin is a structural polysaccharide found in insect exoskeletons and fungal cell walls.
Correct answer is: Chitin
Q.25 Which is NOT a nitrogenous base in DNA?
Adenine
Guanine
Uracil
Cytosine
Explanation - Uracil is found in RNA, not DNA. DNA contains adenine, guanine, cytosine, and thymine.
Correct answer is: Uracil