1. Which of the following is NOT a component of a nucleotide?
A) Phosphate group
B) Nitrogenous base
C) Glycerol backbone
D) Sugar molecule
Answer: C) Glycerol backbone
2. The sugar molecule in RNA is:
A) Deoxyribose
B) Ribose
C) Glucose
D) Fructose
Answer: B) Ribose
3. Which nitrogenous base is found in RNA but not in DNA?
A) Thymine
B) Uracil
C) Cytosine
D) Adenine
Answer: B) Uracil
4. Which nitrogenous base pairs with adenine in DNA?
A) Thymine
B) Uracil
C) Guanine
D) Cytosine
Answer: A) Thymine
5. Which nitrogenous base pairs with adenine in RNA?
A) Thymine
B) Uracil
C) Cytosine
D) Guanine
Answer: B) Uracil
6. Nucleotides are the building blocks of which macromolecules?
A) Proteins
B) Lipids
C) DNA and RNA
D) Carbohydrates
Answer: C) DNA and RNA
7. How many phosphate groups are present in a nucleoside triphosphate?
A) One
B) Two
C) Three
D) Four
Answer: C) Three
8. The process by which nucleotides are linked together to form DNA and RNA is called:
A) Replication
B) Translation
C) Transcription
D) Polymerization
Answer: D) Polymerization
9. Which of the following is NOT a purine?
A) Adenine
B) Guanine
C) Cytosine
D) Thymine
Answer: C) Cytosine
10. The complementary base pair to cytosine in DNA is:
A) Thymine
B) Adenine
C) Guanine
D) Uracil
Answer: C) Guanine
11. What is the sugar component of a nucleotide in DNA?
A) Ribose
B) Deoxyribose
C) Glucose
D) Fructose
Answer: B) Deoxyribose
12. In RNA, the base pairing follows A-U and G-C. Which base pairs with thymine in DNA?
A) Uracil
B) Cytosine
C) Adenine
D) Guanine
Answer: A) Uracil
13. Which type of bond holds the nitrogenous bases together in a DNA molecule?
A) Ionic bond
B) Hydrogen bond
C) Covalent bond
D) Peptide bond
Answer: B) Hydrogen bond
14. Which of the following nucleotides is part of both DNA and RNA?
A) Guanine
B) Thymine
C) Uracil
D) Adenine
Answer: A) Guanine
15. The process of DNA replication involves the addition of nucleotides to the growing DNA strand. What enzyme catalyzes this process?
A) Ligase
B) DNA polymerase
C) Helicase
D) RNA polymerase
Answer: B) DNA polymerase
16. Which of the following is the correct base pairing in DNA?
A) A-T, G-C
B) A-G, T-C
C) A-C, G-T
D) A-C, T-G
Answer: A) A-T, G-C
17. Which of the following is a pyrimidine base?
A) Guanine
B) Adenine
C) Thymine
D) Cytosine
Answer: C) Thymine
18. The sugar-phosphate backbone of DNA is held together by:
A) Hydrogen bonds
B) Peptide bonds
C) Phosphodiester bonds
D) Glycosidic bonds
Answer: C) Phosphodiester bonds
19. In RNA, the base guanine pairs with which of the following?
A) Thymine
B) Adenine
C) Uracil
D) Cytosine
Answer: D) Cytosine
20. Which type of bond connects the phosphate group to the sugar in a nucleotide?
A) Hydrogen bond
B) Peptide bond
C) Phosphodiester bond
D) Ionic bond
Answer: C) Phosphodiester bond
21. In a DNA double helix, the two strands are oriented in which direction?
A) Both in the 5′ to 3′ direction
B) Both in the 3′ to 5′ direction
C) Antiparallel, one 5′ to 3′ and the other 3′ to 5′
D) Parallel
Answer: C) Antiparallel, one 5′ to 3′ and the other 3′ to 5′
22. Which of the following is a function of RNA?
A) Protein synthesis
B) Storage of genetic information
C) Enzyme catalysis
D) Energy storage
Answer: A) Protein synthesis
23. Which of the following is true about the structure of DNA?
A) It is a single-stranded molecule
B) It contains thymine, cytosine, adenine, and uracil
C) The strands are complementary and form a double helix
D) It is composed of ribose sugar
Answer: C) The strands are complementary and form a double helix
24. What is the role of the nitrogenous base in a nucleotide?
A) It stores genetic information
B) It catalyzes reactions
C) It provides energy for the cell
D) It forms the sugar-phosphate backbone
Answer: A) It stores genetic information
25. Which of the following nucleotides is a component of DNA?
A) Uracil
B) Thymine
C) Ribose
D) Adenine
Answer: B) Thymine
26. Which of the following best describes the function of ATP, a nucleotide?
A) Energy storage and transfer
B) Genetic material
C) Signal transmission
D) Catalysis of biochemical reactions
Answer: A) Energy storage and transfer
27. In which organelle does the process of protein synthesis primarily occur?
A) Mitochondrion
B) Nucleus
C) Ribosome
D) Endoplasmic reticulum
Answer: C) Ribosome
28. Which of the following describes the bond between the nitrogenous base and sugar in a nucleotide?
A) Phosphodiester bond
B) Hydrogen bond
C) Glycosidic bond
D) Ionic bond
Answer: C) Glycosidic bond
29. What is the correct sequence of nucleotides in RNA transcription from a DNA template strand?
A) A-T, G-C
B) A-U, G-C
C) A-C, G-T
D) A-T, C-G
Answer: B) A-U, G-C
30. Which of the following is the correct sequence of events in transcription?
A) DNA → mRNA → Protein
B) DNA → Protein → mRNA
C) mRNA → DNA → Protein
D) Protein → DNA → mRNA
Answer: A) DNA → mRNA → Protein
These MCQs and answers provide a solid foundation for understanding the structure, function, and role of nucleotides in DNA and RNA.
