Biomolecules Quiz - ICSE Class 12 Chemistry

Free practice quiz: Biomolecules (ICSE Class 12 Chemistry). 48 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

This ICSE Class 12 Chemistry practice quiz has 48 multiple-choice questions on Biomolecules, and 48 of them come with an explanation. Try the 5 sample questions below (tap an option to check yourself), then play the full quiz online. No sign-up needed.

Sample questions

1. The Zwitterionic form of an amino acid is characterized by:

   1. Presence of a free amino group and a free carboxyl group.
   2. Presence of a negatively charged amino group and a positively charged carboxyl group.
   3. Presence of a positively charged amino group and a negatively charged carboxyl group.
   4. Presence of a neutral amino group and a neutral carboxyl group.
   Show answer

   Answer: C. Presence of a positively charged amino group and a negatively charged carboxyl group.

   A Zwitterion is an internal salt formed by an amino acid where the amino group is protonated (positively charged, -NH3+) and the carboxyl group is deprotonated (negatively charged, -COO-) at physiological pH. This makes the overall molecule electrically neutral.

2. The complete hydrolysis of a complex carbohydrate (polysaccharide) like starch would yield which of the following monosaccharides?

   1. Fructose
   2. Galactose
   3. Glucose
   4. Sucrose
   Show answer

   Answer: C. Glucose

   Starch is a polymer of glucose units linked by glycosidic bonds. Complete hydrolysis breaks all these bonds, yielding individual glucose molecules.

3. A competitive inhibitor of an enzyme typically:

   1. Binds to the allosteric site of the enzyme.
   2. Decreases the Vmax of the reaction.
   3. Binds to the active site of the enzyme, competing with the substrate.
   4. Is permanently bound to the enzyme.
   Show answer

   Answer: C. Binds to the active site of the enzyme, competing with the substrate.

   Competitive inhibitors are molecules that resemble the substrate and bind to the enzyme's active site. This binding prevents the substrate from accessing the active site, thus inhibiting the reaction. Competitive inhibition affects the Km but not the Vmax.

4. The tertiary structure of a protein is stabilized by various types of interactions between amino acid side chains. Which interaction is strongest in stabilizing the tertiary structure of a protein in a physiological environment?

   1. Hydrophobic interactions
   2. Ionic bonds
   3. Hydrogen bonds
   4. Disulfide bonds
   Show answer

   Answer: D. Disulfide bonds

   Disulfide bonds are covalent bonds formed between sulfur atoms of cysteine residues. They are significantly stronger than non-covalent interactions like hydrophobic interactions, ionic bonds, and hydrogen bonds, making them the most potent stabilizers of tertiary protein structure.

5. The process of DNA replication results in the formation of two DNA molecules, each consisting of one original strand and one newly synthesized strand. This is known as:

   1. Conservative replication
   2. Dispersive replication
   3. Semi-conservative replication
   4. Random replication
   Show answer

   Answer: C. Semi-conservative replication

   Semi-conservative replication means that each new DNA molecule consists of one strand from the parent DNA molecule and one newly synthesized strand, ensuring accurate inheritance of genetic information.

More questions in this quiz

Answers and explanations are in the full quiz.

1. Which type of linkage is responsible for maintaining the tertiary structure of a protein by covalent bonding between the sulfhydryl groups of cysteine residues?
2. The secondary structure of a protein refers to the arrangement of the polypeptide chain into alpha-helices and beta-pleated sheets, which are stabilized primarily by:
3. Which of the following statements accurately describes the function of enzymes in biological systems?
4. The process of converting the genetic information encoded in mRNA into a sequence of amino acids in a protein is known as:
5. Which vitamin is synthesized in the skin upon exposure to sunlight and is essential for calcium absorption and bone health?
6. A peptide bond is formed by the reaction between the alpha-amino group of one amino acid and the alpha-carboxyl group of another amino acid. This reaction is a type of:
7. Lipids are a diverse group of hydrophobic molecules. Which of the following is NOT a characteristic feature of lipids?
8. Nucleotides, the building blocks of nucleic acids, consist of three components. Which of the following is NOT one of these components?
9. Which of the following describes the primary structure of a protein?
10. A cofactor is a non-protein chemical compound required for an enzyme's biological activity. If the cofactor is an organic molecule, it is called a(n):
11. During protein denaturation, which level of protein structure is typically disrupted first and most easily?
12. Which of the following lipids is a major component of cell membranes and possesses a hydrophilic head and a hydrophobic tail?
13. The genetic code is degenerate, meaning that:
14. A polysaccharide that serves as a readily available source of glucose for energy in animal cells is:
15. When an enzyme binds to its substrate, it forms an enzyme-substrate complex. This binding is typically described by the Lock and Key model or the Induced Fit model. Which model suggests that the enzyme's active site changes shape upon substrate binding to achieve a tighter fit?
16. Which functional group is characteristic of a fatty acid?
17. The anticodon on a tRNA molecule is complementary to a specific codon on the mRNA molecule. If an mRNA codon is 5'-AUG-3', what is the anticodon on the corresponding tRNA molecule?
18. Which type of biomolecule is primarily responsible for storing genetic information in most living organisms?
19. The specific sequence of amino acids in a protein determines its higher-order structures and ultimately its function. This sequence is dictated by the genetic code carried in:
20. Which monosaccharide is an aldopentose, meaning it is a five-carbon sugar with an aldehyde functional group?
21. The process by which DNA is used as a template to synthesize RNA is called:
22. Which of the following vitamins is water-soluble and acts as an antioxidant, protecting cells from damage by free radicals?
23. A non-competitive inhibitor affects enzyme activity by:
24. The linkage between glycerol and fatty acids in a triglyceride molecule is a(n):
25. Which of the following is a correct representation of the complementary base pairing in DNA?
26. The hydrolysis of a disaccharide like sucrose yields:
27. Which of the following best describes the role of tRNA in protein synthesis?
28. The denaturation of a protein can be caused by factors such as heat, extreme pH, or certain chemicals. Which of the following statements about denaturation is FALSE?
29. When a saturated fatty acid is compared to an unsaturated fatty acid with the same number of carbon atoms, the unsaturated fatty acid will have:
30. Which of the following is a pyrimidine base found in DNA?
31. The overall three-dimensional shape of a protein, including the arrangement of multiple polypeptide subunits, is referred to as its:
32. If the pH of a solution is increased above the isoelectric point (pI) of an amino acid, the amino acid will predominantly exist as:
33. Which of the following enzymes is responsible for catalyzing the formation of peptide bonds between amino acids during protein synthesis?
34. The carbohydrate molecule that serves as the primary energy currency of the cell is:
35. Which class of biomolecules is characterized by long chains of monosaccharides linked by glycosidic bonds?
36. Which vitamin is essential for blood clotting and is synthesized by gut bacteria?
37. The 'lock and key' model of enzyme action suggests that:
38. Which type of lipid is a steroid backbone, consisting of four fused carbon rings, and plays roles in cell membranes and as hormones?
39. If a gene sequence is transcribed into mRNA and then translated into a protein, which molecule directly carries the amino acid to the ribosome for protein synthesis?
40. Which of the following describes the tertiary structure of a protein?
41. The anticodon on a tRNA molecule pairs with the codon on an mRNA molecule. If a tRNA has the anticodon 3'-UAC-5', it will bind to an mRNA codon with the sequence:
42. A catalyst that speeds up a biochemical reaction by lowering the activation energy without being consumed is known as:
43. Which of the following is a disaccharide formed from two glucose units?

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