NEET UG · Biology

Biomolecules

📝 Take Biomolecules Mock Test

Biomolecules Practice Questions

50 questions — tap any to view the full solution.

1. The presence of a specific enzyme allows a reaction to proceed much faster than it would spontaneously. However, the enzyme does not alter the equilibrium constant (Keq) of the reaction. This means the enzyme: 2. In humans, which of the following biomolecules provides the highest energy yield per gram upon complete oxidation? 3. Which of the following is NOT a general function of proteins in living organisms? 4. How does a non-competitive inhibitor affect enzyme kinetics? 5. Which feature distinguishes RNA from DNA? 6. Which of the following statements accurately describes the composition of a nucleoside? 7. In a typical eukaryotic cell, which of the following polysaccharides is primarily used for long-term energy storage? 8. A DNA sample is found to have 20% Adenine. What percentage of the DNA is double-stranded? 9. Which of the following is an example of an allosteric enzyme? 10. Which of the following statements correctly describes the synthesis of a triglyceride? 11. Consider a mutation in a gene that results in the replacement of a nonpolar amino acid with a charged amino acid in the interior of a globular protein. What is the most likely consequence? 12. A deficiency in Vitamin D, which is a steroid hormone precursor, can lead to weakened bones. This indicates a primary role of a specific biomolecule class in bone health. Which class is it? 13. Which of the following is a key difference between fibrous and globular proteins? 14. What is the main reason why DNA is more stable than RNA in aqueous solutions? 15. An enzyme is isolated from a thermophilic bacterium. Compared to an enzyme from a mesophilic bacterium, what would be a key characteristic of the thermophilic enzyme? 16. Which of the following is true regarding saturated vs. unsaturated fatty acids? 17. Which of the following would be least affected by denaturation caused by extreme pH or high temperature? 18. If a person consumes a diet rich in insoluble fiber (like cellulose), which of the following is the most likely physiological outcome? 19. Which of the following is a characteristic of ribosomes, primarily composed of ribosomal RNA (rRNA) and proteins? 20. What happens to an enzyme's activity when its optimal temperature is exceeded significantly? 21. Why are fatty acids with double bonds (unsaturated) generally liquid at room temperature, while saturated fatty acids are solid? 22. A common feature of both ATP and RNA is the presence of: 23. Which of the following bonds are primarily responsible for maintaining the stability of the alpha-helical and beta-pleated sheet structures in proteins? 24. The pK values of an amino acid are pK1 (carboxyl group) = 2.34 and pK2 (amino group) = 9.60. What is the approximate isoelectric point (pI) of this amino acid? 25. What is the primary function of the carbohydrate component of a glycoprotein on the outer surface of a cell membrane? 26. Which of the following scenarios best illustrates the 'induced fit' model of enzyme action? 27. If a double-stranded DNA molecule is heated, the two strands separate (melt). Which DNA molecule would require the highest temperature to melt, given the same length? 28. Which of the following compounds is classified as a derived lipid, known for its role in inflammatory responses and smooth muscle contraction? 29. Assertion: Cellulose is not digestible by humans, while starch is. Reason: Cellulose is made of beta-glucose units, forming straight chains, whereas starch is made of alpha-glucose units, forming helical structures. 30. Which level of protein structure is most directly determined by the sequence of amino acids in the polypeptide chain? 31. In an RNA molecule, which of the following pairs of nitrogenous bases are capable of forming hydrogen bonds with each other? 32. Which class of lipids is the most abundant in cell membranes and forms the lipid bilayer? 33. Which of the following is NOT a characteristic feature of enzyme-catalyzed reactions? 34. The process of forming a glycosidic bond between two monosaccharides involves the removal of which molecule? 35. Which of the following polysaccharides is primarily found in the exoskeletons of arthropods and cell walls of fungi, and is composed of N-acetylglucosamine units? 36. Which characteristic allows amino acids to act as buffers, resisting changes in pH? 37. A long chain of repeated nucleotide units linked by phosphodiester bonds forms a nucleic acid. If a segment of DNA is 100 base pairs long, how many phosphodiester bonds are present in this segment? 38. Which of the following statements about the role of cholesterol in animal cell membranes is accurate? 39. Which of the following is an example of a secondary metabolite in plants that often serves as a defense mechanism against herbivores or pathogens? 40. A drug is developed that binds tightly to the active site of an enzyme but does not undergo catalysis. This binding prevents the natural substrate from interacting with the enzyme. What type of inhibition is described here? 41. Glycogen is often referred to as "animal starch." Which of the following structural features does glycogen share with amylopectin (a component of starch) that makes it an efficient energy storage molecule? 42. A nucleic acid sample from an unknown organism is analyzed. It contains Adenine (A), Guanine (G), Cytosine (C), and Uracil (U). Based on this information, which conclusion is most appropriate? 43. The fluidity of a cell membrane is primarily influenced by the composition of its fatty acids. Which type of fatty acid would tend to increase membrane fluidity? 44. Which amino acid plays a crucial role in forming disulfide bridges, which are covalent bonds critical for stabilizing the tertiary and sometimes quaternary structure of proteins? 45. Which of the following correctly describes a competitive inhibitor of an enzyme? 46. Which of the following statements correctly differentiates between starch and cellulose? 47. If a DNA strand has the sequence 5'-ATGCGTAC-3', what will be the sequence of the complementary strand? 48. An enzyme exhibits optimal activity at pH 7.0 and 37°C. If the pH is lowered to 2.0, what would be the most likely effect on the enzyme's activity and why? 49. Which type of lipid is characterized by a four-ring hydrocarbon structure and serves as a precursor for various hormones and a component of animal cell membranes? 50. Which of the following statements about the secondary structure of proteins is correct?