50 Most Important NEET PYQs of Chapter 9: Biomolecules – Part 1 (Q1–25)

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🧬 50 Most Important NEET PYQs of Chapter 9: Biomolecules – Part 1 (Q1–25)

1. Which of the following is not a carbohydrate?
A) Glucose
B) Fructose
C) Sucrose
D) Urea
✅ Answer: D) Urea
Explanation: Urea is a nitrogenous waste, not a carbohydrate. Glucose, fructose, and sucrose are all carbohydrates.

2. Which of the following is a disaccharide?
A) Glucose
B) Sucrose
C) Fructose
D) Glucagon
✅ Answer: B) Sucrose
Explanation: Sucrose is a disaccharide, made up of glucose and fructose. Glucose and fructose are monosaccharides, and glucagon is a hormone.

3. Which of the following amino acids contains a sulfur atom?
A) Alanine
B) Glycine
C) Cysteine
D) Leucine
✅ Answer: C) Cysteine
Explanation: Cysteine contains a sulfur atom in its side chain, forming a disulfide bond which is important in protein structure.

4. The primary structure of a protein is determined by:
A) The sequence of amino acids
B) The folding of the polypeptide chain
C) The interactions between the side chains
D) The disulfide bonds
✅ Answer: A) The sequence of amino acids
Explanation: The primary structure of a protein refers to the linear sequence of amino acids, which determines the protein's overall shape and function.

5. Which of the following is a polymer of glucose?
A) Cellulose
B) Sucrose
C) Fructose
D) Starch
✅ Answer: A) Cellulose
Explanation: Cellulose is a polymer made of glucose monomers. Starch is also a glucose polymer, but cellulose has a different structure, making it indigestible by humans.

6. What is the bond that links amino acids in a protein?
A) Hydrogen bond
B) Ionic bond
C) Peptide bond
D) Phosphodiester bond
✅ Answer: C) Peptide bond
Explanation: Peptide bonds link amino acids in a protein, forming a polypeptide chain.

7. Which of the following is the main structural component of the cell membrane?
A) Proteins
B) Lipids
C) Carbohydrates
D) Nucleic acids
✅ Answer: B) Lipids
Explanation: Lipids, particularly phospholipids, form the basic structure of the cell membrane, providing fluidity and selective permeability.

8. Which of the following is the characteristic feature of enzymes?
A) They increase the activation energy of a reaction.
B) They are permanently changed after a reaction.
C) They lower the activation energy of a reaction.
D) They are used up during a reaction.
✅ Answer: C) They lower the activation energy of a reaction
Explanation: Enzymes act as biological catalysts by lowering the activation energy required for chemical reactions to occur.

9. What is the function of nucleotides in nucleic acids?
A) They form the genetic code.
B) They store energy.
C) They form structural components of the cell membrane.
D) They carry out enzymatic functions.
✅ Answer: A) They form the genetic code
Explanation: Nucleotides are the building blocks of nucleic acids (DNA and RNA) and form the genetic code that determines the synthesis of proteins.

10. Which of the following is an example of a purine base?
A) Thymine
B) Uracil
C) Cytosine
D) Adenine
✅ Answer: D) Adenine
Explanation: Adenine is a purine base, while thymine, uracil, and cytosine are pyrimidines.

11. The tertiary structure of a protein is stabilized by:
A) Peptide bonds
B) Disulfide bridges
C) Hydrogen bonds
D) Both B and C
✅ Answer: D) Both B and C
Explanation: The tertiary structure of a protein is stabilized by hydrogen bonds and disulfide bridges between the side chains of amino acids.

12. Which of the following is a feature of enzymes?
A) Enzymes are consumed in the reaction.
B) Enzymes work in a specific pH range.
C) Enzymes cannot be reused.
D) Enzymes increase the activation energy.
✅ Answer: B) Enzymes work in a specific pH range
Explanation: Enzymes are highly specific for their substrates and typically function optimally within a specific pH range.

13. Which of the following is not a polysaccharide?
A) Starch
B) Cellulose
C) Glycogen
D) Sucrose
✅ Answer: D) Sucrose
Explanation: Sucrose is a disaccharide, not a polysaccharide. Starch, cellulose, and glycogen are all polysaccharides.

14. The function of lipids in the human body includes all of the following except:
A) Energy storage
B) Insulation
C) Hormone production
D) Enzyme catalysis
✅ Answer: D) Enzyme catalysis
Explanation: Lipids are involved in energy storage, insulation, and hormone production, but they do not function in enzyme catalysis, which is the role of proteins.

15. The building blocks of proteins are:
A) Nucleotides
B) Fatty acids
C) Amino acids
D) Monosaccharides
✅ Answer: C) Amino acids
Explanation: Proteins are made up of amino acids, which are linked together by peptide bonds to form polypeptides.

16. Which of the following is a coenzyme?
A) Vitamin C
B) Nicotinamide
C) NAD+
D) ATP
✅ Answer: C) NAD+
Explanation: NAD+ (Nicotinamide adenine dinucleotide) is a coenzyme that plays a key role in redox reactions in cells.

17. In a double-stranded DNA molecule, the two strands are held together by:
A) Covalent bonds
B) Ionic bonds
C) Hydrogen bonds
D) Disulfide bonds
✅ Answer: C) Hydrogen bonds
Explanation: The two strands of DNA are held together by hydrogen bonds between complementary nitrogenous bases (adenine with thymine, and cytosine with guanine).

18. Which of the following is the primary function of RNA?
A) Energy storage
B) Genetic information storage
C) Protein synthesis
D) Enzyme catalysis
✅ Answer: C) Protein synthesis
Explanation: RNA plays a crucial role in protein synthesis by carrying the genetic code from DNA to ribosomes for translation into proteins.

19. What is the function of peptidoglycan in bacterial cells?
A) To store energy
B) To form the cell wall
C) To help in DNA replication
D) To synthesize proteins
✅ Answer: B) To form the cell wall
Explanation: Peptidoglycan is a polymer that forms the cell wall of bacterial cells, providing structural support and protection.

20. Which of the following proteins is involved in muscle contraction?
A) Collagen
B) Actin
C) Hemoglobin
D) Insulin
✅ Answer: B) Actin
Explanation: Actin is a protein involved in muscle contraction, working in conjunction with myosin.

21. Which of the following is not a feature of enzymes?
A) They speed up chemical reactions
B) They are specific to their substrates
C) They can be reused
D) They are consumed during the reaction
✅ Answer: D) They are consumed during the reaction
Explanation: Enzymes are not consumed during a reaction and can be reused multiple times.

22. Which of the following is a function of DNA?
A) Synthesis of proteins
B) Energy storage
C) Information storage for heredity
D) Structural support
✅ Answer: C) Information storage for heredity
Explanation: DNA stores genetic information that is passed down to offspring, guiding the synthesis of proteins that determine an organism's traits.

23. Which of the following enzymes is involved in DNA replication?
A) Amylase
B) DNA polymerase
C) Pepsin
D) Ligase
✅ Answer: B) DNA polymerase
Explanation: DNA polymerase is the enzyme that synthesizes a new strand of DNA during replication.

24. Which of the following vitamins is water-soluble?
A) Vitamin A
B) Vitamin D
C) Vitamin C
D) Vitamin E
✅ Answer: C) Vitamin C
Explanation: Vitamin C is a water-soluble vitamin, while the others are fat-soluble.

25. The structure of an enzyme is most affected by:
A) The concentration of the substrate
B) The temperature and pH
C) The presence of cofactors
D) The type of substrate
✅ Answer: B) The temperature and pH
Explanation: Enzyme activity is sensitive to changes in temperature and pH, which can alter the enzyme's three-dimensional structure and function.

Stay tuned for Part 2 (Q26–50) coming up soon!

For more detailed explanations and NEET biology preparation, be sure to follow:

🔗 neetpyqall.blogspot.com
🔗 biologyatease1.blogspot.com


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