Biology – Biomolecules MCQ

Biomolecules are the building blocks of life, encompassing a range of organic molecules that are essential for the structure and function of living organisms. Let’s explore the fascinating world of biomolecules with these 25 Multiple Choice Questions (MCQs) tailored for beginners. Each question comes with an answer and a concise explanation to help you understand the core concepts better. So, let’s get started!

1. Which of the following is considered a monomer of proteins?

a) Amino acid
b) Nucleotide
c) Fatty acid
d) Glucose

Answer:

a) Amino acid

Explanation:

Amino acids are the building blocks (monomers) of proteins. They combine to form polymers called polypeptides, which fold into functional proteins.

2. What is the primary function of carbohydrates in the body?

a) Energy storage
b) Insulation
c) Providing structure
d) Quick energy source

Answer:

d) Quick energy source

Explanation:

Carbohydrates primarily serve as a quick source of energy for the body, especially for the brain and muscles.

3. Which biomolecule is responsible for storing genetic information?

a) DNA
b) RNA
c) Protein
d) Lipid

Answer:

a) DNA

Explanation:

DNA (Deoxyribonucleic Acid) stores genetic information in cells and is responsible for hereditary traits.

4. What is the main component of cell membranes?

a) Proteins
b) Nucleic acids
c) Polysaccharides
d) Phospholipids

Answer:

d) Phospholipids

Explanation:

Phospholipids form the basic structure of cell membranes, creating a lipid bilayer that separates the interior of the cell from the external environment.

5. Which of the following is NOT a function of proteins?

a) Catalyzing biochemical reactions
b) Storing genetic information
c) Providing structural support
d) Transporting molecules

Answer:

b) Storing genetic information

Explanation:

Proteins have various functions including catalysis, structural support, and transport, but they do not store genetic information.

6. What is the function of enzymes?

a) Store energy
b) Catalyze biochemical reactions
c) Provide structural support to cells
d) Store genetic information

Answer:

b) Catalyze biochemical reactions

Explanation:

Enzymes are proteins that act as biological catalysts to speed up biochemical reactions in the body.

7. Which of the following biomolecules is hydrophobic?

a) Proteins
b) Carbohydrates
c) Lipids
d) Nucleic acids

Answer:

c) Lipids

Explanation:

Lipids are hydrophobic, meaning they do not mix with water. This property is essential for the formation of cell membranes.

8. What is the function of RNA?

a) Storing energy
b) Building cell membranes
c) Protein synthesis
d) Insulating body organs

Answer:

c) Protein synthesis

Explanation:

RNA (Ribonucleic Acid) plays a crucial role in protein synthesis, acting as a messenger and a builder of proteins.

9. Which type of carbohydrate is cellulose?

a) Monosaccharide
b) Disaccharide
c) Polysaccharide
d) Oligosaccharide

Answer:

c) Polysaccharide

Explanation:

Cellulose is a polysaccharide, consisting of a long chain of glucose molecules, and it provides structural support to plant cell walls.

10. Which of the following bases is found in RNA but not in DNA?

a) Adenine
b) Cytosine
c) Thymine
d) Uracil

Answer:

d) Uracil

Explanation:

Uracil is a nitrogenous base found in RNA, replacing thymine, which is present in DNA.

11. Which type of lipid is cholesterol?

a) Steroid
b) Triglyceride
c) Phospholipid
d) Fatty acid

Answer:

a) Steroid

Explanation:

Cholesterol is a type of steroid lipid, important for cell membrane structure and the synthesis of hormones.

12. What is the primary structure of a protein determined by?

a) Hydrogen bonds
b) The sequence of amino acids
c) Disulfide bridges
d) Hydrophobic interactions

Answer:

b) The sequence of amino acids

Explanation:

The primary structure of a protein is determined by the sequence of amino acids in its polypeptide chain.

13. Which of the following biomolecules can act as hormones?

a) Proteins
b) Lipids
c) Nucleic acids
d) Both a and b

Answer:

d) Both a and b

Explanation:

Both proteins and lipids can act as hormones, serving as chemical messengers in the body.

14. What is glycogen?

a) A protein
b) A nucleic acid
c) A lipid
d) A carbohydrate

Answer:

d) A carbohydrate

Explanation:

Glycogen is a polysaccharide carbohydrate, serving as the primary storage form of glucose in animals.

15. Which of the following is NOT a nucleotide in DNA?

a) Adenine
b) Cytosine
c) Guanine
d) Ribose

Answer:

d) Ribose

Explanation:

Ribose is a sugar, not a nucleotide. The nucleotides in DNA are Adenine, Cytosine, Guanine, and Thymine.

16. Which of the following molecules acts as an energy currency for cells?

a) Glucose
b) ATP
c) DNA
d) Amino acid

Answer:

b) ATP

Explanation:

ATP (Adenosine Triphosphate) acts as the energy currency of the cell, providing energy for various cellular functions.

17. Which of the following is a characteristic of saturated fats?

a) They have double bonds between carbon atoms
b) They are solid at room temperature
c) They are liquid at room temperature
d) They contain less hydrogen atoms

Answer:

b) They are solid at room temperature

Explanation:

Saturated fats have no double bonds between carbon atoms, making them solid at room temperature.

18. Which type of RNA carries amino acids to the ribosome during protein synthesis?

a) mRNA
b) tRNA
c) rRNA
d) snRNA

Answer:

b) tRNA

Explanation:

Transfer RNA (tRNA) carries amino acids to the ribosome during protein synthesis.

19. Which biomolecule serves as a catalyst in metabolic reactions to lower the activation energy?

a) Enzymes
b) Nucleic acids
c) Carbohydrates
d) Lipids

Answer:

a) Enzymes

Explanation:

Enzymes are proteins that act as catalysts in metabolic reactions, lowering the activation energy required for the reaction to proceed.

20. What is the function of a nucleotide in DNA?

a) Provides energy
b) Forms the genetic code
c) Acts as an enzyme
d) Serves as a structural component of the cell membrane

Answer:

b) Forms the genetic code

Explanation:

Nucleotides in DNA form the genetic code, carrying genetic information necessary for the synthesis of proteins and other cellular activities.

21. Which carbohydrate is known as table sugar?

a) Glucose
b) Fructose
c) Lactose
d) Sucrose

Answer:

d) Sucrose

Explanation:

Sucrose is commonly known as table sugar, consisting of one glucose and one fructose molecule.

22. Which type of bond is formed between amino acids to make a protein?

a) Ionic bond
b) Covalent bond
c) Hydrogen bond
d) Peptide bond

Answer:

d) Peptide bond

Explanation:

A peptide bond is a covalent bond formed between the amino group of one amino acid and the carboxyl group of another, linking amino acids to form a protein.

23. What is the function of lipids in the human body?

a) Quick energy source
b) Energy storage and insulation
c) Catalyzing biochemical reactions
d) Providing structural support to the cell membrane

Answer:

b) Energy storage and insulation

Explanation:

Lipids function mainly as a long-term energy storage and insulator in the human body, in addition to other roles like forming cell membranes.

24. Which type of RNA is responsible for bringing the genetic code from the DNA in the nucleus to the ribosomes in the cytoplasm?

a) mRNA
b) tRNA
c) rRNA
d) snRNA

Answer:

a) mRNA

Explanation:

Messenger RNA (mRNA) is responsible for carrying the genetic code from the DNA in the nucleus to the ribosomes in the cytoplasm for protein synthesis.

25. What is the building block of a nucleic acid?

a) Amino acid
b) Fatty acid
c) Monosaccharide
d) Nucleotide

Answer:

d) Nucleotide

Explanation:

Nucleotides are the building blocks of nucleic acids, consisting of a phosphate group, a sugar, and a nitrogenous base.


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