Q.1 Which of the following is the primary building block of proteins?
Amino acids
Nucleotides
Monosaccharides
Fatty acids
Explanation - Proteins are polymers made up of amino acids linked by peptide bonds.
Correct answer is: Amino acids
Q.2 Which sugar is the main energy source in human cells?
Fructose
Glucose
Galactose
Sucrose
Explanation - Glucose is the primary energy source used in cellular respiration to produce ATP.
Correct answer is: Glucose
Q.3 DNA is made up of repeating units called:
Amino acids
Nucleotides
Peptides
Fatty acids
Explanation - DNA is a polymer of nucleotides, each containing a sugar, phosphate, and nitrogenous base.
Correct answer is: Nucleotides
Q.4 Which vitamin is essential for blood clotting?
Vitamin A
Vitamin C
Vitamin K
Vitamin D
Explanation - Vitamin K is necessary for the synthesis of clotting factors in blood.
Correct answer is: Vitamin K
Q.5 Which biomolecule is the main component of cell membranes?
Proteins
Lipids
Carbohydrates
Nucleic acids
Explanation - Phospholipids form the bilayer structure of cell membranes.
Correct answer is: Lipids
Q.6 Which of the following is a disaccharide?
Glucose
Fructose
Sucrose
Galactose
Explanation - Sucrose is a disaccharide composed of glucose and fructose.
Correct answer is: Sucrose
Q.7 What type of bond connects amino acids in a protein?
Ionic bond
Peptide bond
Hydrogen bond
Glycosidic bond
Explanation - Peptide bonds form between the amino group of one amino acid and the carboxyl group of another.
Correct answer is: Peptide bond
Q.8 Which molecule carries genetic information in most living organisms?
RNA
DNA
Protein
Lipid
Explanation - DNA stores genetic information and transmits it during cell division.
Correct answer is: DNA
Q.9 Enzymes act as:
Energy sources
Catalysts
Hormones
Transporters
Explanation - Enzymes speed up biochemical reactions by lowering activation energy.
Correct answer is: Catalysts
Q.10 Which element is present in all amino acids?
Sulfur
Nitrogen
Phosphorus
Chlorine
Explanation - Amino acids contain nitrogen in their amino (-NH2) group.
Correct answer is: Nitrogen
Q.11 Which of the following lipids is the main storage form of energy in humans?
Phospholipids
Triglycerides
Cholesterol
Steroids
Explanation - Triglycerides store energy in fat tissue for long-term use.
Correct answer is: Triglycerides
Q.12 The double-helix structure of DNA was discovered by:
Darwin and Mendel
Watson and Crick
Franklin and Wilkins
Pauling and Sanger
Explanation - James Watson and Francis Crick proposed the double-helix model in 1953.
Correct answer is: Watson and Crick
Q.13 Which nitrogenous base is found in RNA but not in DNA?
Adenine
Thymine
Uracil
Cytosine
Explanation - RNA uses uracil instead of thymine found in DNA.
Correct answer is: Uracil
Q.14 Hemoglobin is a:
Lipid
Protein
Carbohydrate
Nucleic acid
Explanation - Hemoglobin is a protein that carries oxygen in red blood cells.
Correct answer is: Protein
Q.15 Which of these is an essential amino acid?
Glycine
Valine
Alanine
Serine
Explanation - Valine is essential because it cannot be synthesized by the human body.
Correct answer is: Valine
Q.16 ATP stores energy in which type of bond?
Glycosidic bonds
Peptide bonds
Phosphoanhydride bonds
Ionic bonds
Explanation - The high-energy phosphate bonds in ATP release energy when broken.
Correct answer is: Phosphoanhydride bonds
Q.17 Which organelle is the site of cellular respiration?
Nucleus
Mitochondria
Ribosome
Golgi apparatus
Explanation - Mitochondria are known as the powerhouse of the cell because they produce ATP.
Correct answer is: Mitochondria
Q.18 Insulin is primarily responsible for:
Breaking down fats
Storing glycogen
Regulating blood glucose
Transporting oxygen
Explanation - Insulin lowers blood glucose by facilitating its uptake into cells.
Correct answer is: Regulating blood glucose
Q.19 Which of the following is a polysaccharide?
Glucose
Sucrose
Starch
Fructose
Explanation - Starch is a storage polysaccharide found in plants.
Correct answer is: Starch
Q.20 The genetic code is carried by:
tRNA
mRNA
rRNA
snRNA
Explanation - mRNA carries the genetic code from DNA to ribosomes for protein synthesis.
Correct answer is: mRNA
Q.21 Which vitamin deficiency causes scurvy?
Vitamin A
Vitamin B12
Vitamin C
Vitamin D
Explanation - Vitamin C deficiency leads to scurvy, characterized by weak connective tissues.
Correct answer is: Vitamin C
Q.22 Which macromolecule is most directly involved in heredity?
Proteins
Carbohydrates
Lipids
Nucleic acids
Explanation - Nucleic acids like DNA and RNA are responsible for genetic information transfer.
Correct answer is: Nucleic acids
Q.23 Which enzyme breaks down starch into maltose?
Amylase
Lipase
Pepsin
Trypsin
Explanation - Amylase, found in saliva, hydrolyzes starch into maltose.
Correct answer is: Amylase
Q.24 Which of the following is not a lipid?
Cholesterol
Phospholipid
Glycogen
Triglyceride
Explanation - Glycogen is a carbohydrate used for energy storage in animals.
Correct answer is: Glycogen
Q.25 What type of sugar is found in DNA?
Ribose
Deoxyribose
Glucose
Fructose
Explanation - DNA contains deoxyribose sugar, while RNA contains ribose.
Correct answer is: Deoxyribose