1.

Which of the following enzymes is responsible for adding new nucleotides to the growing DNA
strand during DNA replication?
a) RNA polymerase
b) DNA polymerase
c) Ligase
d) Helicase

2. The term “Okazaki fragments” refers to:

a) Small segments of RNA
b) Short DNA fragments synthesized on the lagging strand
c) Long stretches of DNA
d) The loop structure formed during DNA replication

3. The structure of DNA was discovered by:

a) Gregor Mendel
b) Watson and Crick
c) Avery, MacLeod, and McCarty
d) Hershey and Chase

4. In a replication bubble, the area where the strands are being separated is called:
a) Replication fork
b) Origin of replication
c) Okazaki fragment
d) Primer region

5. The central dogma of molecular biology involves the flow of genetic information from:
a) DNA → RNA → Protein
b) RNA → DNA → Protein
c) Protein → RNA → DNA
d) DNA → Protein → RNA

6. Which of the following is the correct sequence for the process of transcription?
a) DNA → mRNA → Protein
b) mRNA → DNA → Protein
c) DNA → tRNA → mRNA
d) mRNA → tRNA → DNA

7. Which type of RNA carries the genetic code from DNA to the ribosome for protein synthesis?
a) rRNA
b) mRNA
c) tRNA
d) hnRNA

8. In a double-stranded DNA molecule, the amount of adenine is always equal to the amount of:
a) Thymine
b) Cytosine
c) Guanine
d) Uracil

9. In a nucleosome, the DNA is wrapped around:

a) Ribosomes
b) Histone proteins
c) mRNA
d) tRNA

10. The replication of DNA is called semi-conservative because:

a) Half of the parental strand is conserved in each new molecule
b) Both strands are conserved
c) Only the newly synthesized strand is conserved
d) None of the above

11. Which of the following is not involved in protein synthesis?

a) Ribosomes
b) tRNA
c) mRNA
d) Telomerase

12. The process by which a single gene produces multiple proteins is known as:
a) Mutation
b) Genetic recombination
c) Alternative splicing
d) Transcription

13. Which of the following is responsible for the termination of transcription in prokaryotes?
a) Rho-dependent termination
b) DNA polymerase
c) Ligase
d) Topoisomerase

14. In a eukaryotic cell, where does transcription occur?

a) Cytoplasm
b) Nucleus
c) Ribosome
d) Mitochondrion

15. Which of the following mutations would most likely result in a nonfunctional protein?
a) Silent mutation
b) Missense mutation
c) Nonsense mutation
d) Frame-shift mutation

16. A segment of DNA coding for a functional RNA or protein is called a:

a) Chromosome
b) Locus
c) Gene
d) Codon

17. Which of the following enzymes unwinds the DNA helix during replication?
a) Helicase
b) Ligase
c) DNA polymerase
d) Topoisomerase
18. The genetic code is said to be universal because:
a) It is identical in all organisms
b) It only applies to bacteria
c) It is identical in human and plant cells
d) It is identical in all prokaryotes

19. Which of the following statements about the promoter is false?

a) It is a sequence of DNA that signals the start of transcription
b) It is recognized by RNA polymerase
c) It is always located at the 5' end of the gene
d) It is part of the intron sequence

20. A codon is composed of how many nucleotides?

a) One
b) Two
c) Three
d) Four

21. In the Hershey-Chase experiment, what was the label used for DNA?
a) Sulfur-35
b) Phosphorus-32
c) Carbon-14
d) Oxygen-18

22. Which of the following correctly describes the function of tRNA?

a) It carries genetic information from the DNA to the ribosome
b) It transfers amino acids to the growing polypeptide chain
c) It catalyzes the formation of peptide bonds
d) It acts as a template for protein synthesis

23. The enzyme that synthesizes RNA during transcription is:

a) DNA polymerase
b) RNA polymerase
c) Ligase
d) Helicase

24. Which one of the following is true about the genetic code?
a) It is degenerate, meaning that several codons can code for the same amino acid
b) It is unambiguous, meaning one codon can code for multiple amino acids
c) It is discontinuous
d) It is identical across all species without any variation

25. The double-helix model of DNA was proposed by:

a) Mendel and Sutton
b) Franklin and Wilkins
c) Watson and Crick
d) Avery and MacLeod

26. A mutation that changes a codon from coding for one amino acid to coding for another amino
acid is called a:
a) Silent mutation
b) Missense mutation
c) Nonsense mutation
d) Frameshift mutation

27. In eukaryotes, the post-transcriptional modifications include all except:

a) Splicing
b) Addition of a 5' cap
c) Addition of a poly-A tail
d) Replication of DNA

28. In the case of the Lac operon, which molecule inhibits transcription when bound to the
operator?
a) cAMP
b) Repressor
c) Activator
d) RNA polymerase

29. In the Hershey-Chase experiment, what was the purpose of using radioactive phosphorus?
a) To label proteins
b) To label DNA
c) To label RNA
d) To label lipids

30. Which of the following enzymes is responsible for proofreading the newly synthesized DNA
strand?
a) DNA polymerase
b) RNA polymerase
c) Ligase
d) Helicase

31. Which of the following best explains the term "genetic recombination" in meiosis?
a) The exchange of genetic material between sister chromatids
b) The process of homologous chromosomes pairing up
c) The exchange of genetic material between non-sister chromatids
d) The splitting of chromosomes during anaphase

32. What is the function of the enzyme topoisomerase during DNA replication?
a) To unwind the DNA strand
b) To relieve the torsional strain caused by unwinding of DNA
c) To synthesize RNA primers
d) To synthesize Okazaki fragments

33. The addition of a methyl group to a DNA molecule, which can alter gene expression, is known
as:
a) Transcriptional regulation
b) Epigenetic modification
c) DNA replication
d) DNA recombination

34. The two strands of DNA are held together by:

a) Hydrogen bonds between complementary bases
b) Ionic bonds between phosphate groups
c) Covalent bonds between sugar molecules
d) Van der Waals forces between nucleotides

35. In prokaryotes, the process of transcription and translation occurs:

a) Simultaneously in the nucleus
b) Simultaneously in the cytoplasm
c) Separately in the nucleus and cytoplasm
d) Simultaneously in the ribosome

36. Which of the following is the key characteristic of the "Hershey-Chase experiment"?
a) Demonstrated that RNA carries genetic material
b) Established that proteins are the genetic material
c) Showed that DNA, not protein, is the genetic material
d) Proved that viruses do not carry genetic information

37. The enzyme responsible for joining the Okazaki fragments on the lagging strand is:
a) Helicase
b) DNA polymerase
c) Ligase
d) Topoisomerase

38. In E. coli, the Lac operon is an example of:

a) Positive gene regulation
b) Negative gene regulation
c) Constitutive gene expression
d) Operon repressor system

39. Which of the following modifications occurs during RNA processing in eukaryotes?
a) Removal of introns
b) Removal of exons
c) Transcription of rRNA
d) Translation of tRNA

40. The sequence of nucleotides on the DNA template strand that specifies the synthesis of a
protein is called the:
a) Exon
b) Intron
c) Gene
d) Anticodon

41. Which of the following mutations will change the reading frame of the genetic message?
a) Missense mutation
b) Nonsense mutation
c) Frame-shift mutation
d) Silent mutation

42. The process of converting mRNA into a functional protein is called:

a) Transcription
b) Translation
c) Replication
d) Translocation

43. The coding sequence of a gene is found in the:

a) Intron
b) Exon
c) Promoter
d) Terminator

44. Which of the following is NOT a type of point mutation?

a) Substitution
b) Insertion
c) Deletion
d) Duplication

45. In prokaryotic transcription, the RNA polymerase binds to the:

a) Operator
b) Promoter
c) Terminator
d) Ribosome

46. The repressor protein in the lac operon of E. coli binds to the:
a) Enhancer region
b) Operator region
c) Promoter region
d) Gene coding region

47. In the synthesis of a protein, which site on the ribosome holds the growing polypeptide chain?
a) A-site
b) P-site
c) E-site
d) T-site

48. Which of the following statements is correct about the genetic code?
a) It is overlapping
b) It is read from 3' to 5' direction
c) It is degenerate, with some amino acids being encoded by more than one codon
d) It is non-universal across all organisms

49. In the double-helix structure of DNA, the two strands are oriented in opposite directions,
which is known as:
a) Antiparallel orientation
b) Complementary pairing
c) Replication fork
d) Semi-conservative replication

50. What is the primary function of ribosomal RNA (rRNA) in protein synthesis?
a) To carry amino acids to the ribosome
b) To provide the template for protein synthesis
c) To form the structure of the ribosome and catalyze peptide bond formation
d) To transcribe the mRNA