NEET UG - Molecular basis of inheritance - DNA structure replication transcription translation genetic code Online Test (MCQ Quiz)

1. What is the fundamental building block of DNA?

A) Amino acid B) Nucleotide C) Monosaccharide D) Fatty acid

2. Which scientist is credited with discovering the double helix structure of DNA?

A) Rosalind Franklin B) Maurice Wilkins C) James Watson and Francis Crick D) Erwin Chargaff

3. In the DNA double helix, which base pairs with Adenine (A)?

A) Guanine (G) B) Cytosine (C) C) Thymine (T) D) Uracil (U)

4. Which of the following is a purine base found in DNA?

A) Thymine B) Cytosine C) Adenine D) Uracil

5. The two strands of DNA are held together by which type of bonds?

A) Covalent bonds B) Peptide bonds C) Hydrogen bonds D) Ionic bonds

6. What is the process by which DNA makes a copy of itself called?

A) Transcription B) Translation C) Replication D) Mutation

7. During DNA replication, which enzyme is primarily responsible for unwinding the DNA double helix?

A) DNA ligase B) Primase C) Helicase D) Topoisomerase

8. Which enzyme synthesizes new DNA strands during replication?

A) RNA polymerase B) DNA polymerase C) Reverse transcriptase D) Telomerase

9. Okazaki fragments are short segments of DNA synthesized on which strand during replication?

A) Leading strand B) Lagging strand C) Template strand D) Coding strand

10. What is the role of DNA ligase in DNA replication?

A) To unwind the DNA helix B) To synthesize new DNA strands C) To join Okazaki fragments D) To remove RNA primers

11. The process of synthesizing RNA from a DNA template is called:

A) Replication B) Translation C) Transcription D) Reverse transcription

12. Which enzyme is responsible for catalyzing transcription?

A) DNA polymerase B) RNA polymerase C) Ribosome D) Peptidyl transferase

13. During transcription, which DNA strand serves as the template for RNA synthesis?

A) Coding strand B) Non-coding strand C) Template strand D) Sense strand

14. In RNA, which base replaces Thymine (T) when pairing with Adenine (A)?

A) Guanine (G) B) Cytosine (C) C) Uracil (U) D) Adenine (A)

15. What is the sequence of events in gene expression?

A) Replication -> Transcription -> Translation B) Transcription -> Translation -> Replication C) Translation -> Transcription -> Replication D) Transcription -> Replication -> Translation

16. The process of synthesizing proteins from an mRNA template is called:

A) Transcription B) Replication C) Translation D) Mutation

17. Where does translation primarily occur in eukaryotic cells?

A) Nucleus B) Ribosomes C) Golgi apparatus D) Endoplasmic reticulum

18. What is the function of transfer RNA (tRNA) in translation?

A) Carries genetic information from DNA B) Carries amino acids to the ribosome C) Forms the structural component of ribosomes D) Catalyzes peptide bond formation

19. What is the role of messenger RNA (mRNA) in translation?

A) Carries amino acids to the ribosome B) Provides the genetic code for protein synthesis C) Forms the ribosomal structure D) Catalyzes peptide bond formation

20. A sequence of three nucleotides on mRNA that specifies an amino acid is called a:

A) Gene B) Codon C) Anticodon D) Intron

21. The genetic code is said to be degenerate because:

A) It is universal B) Multiple codons can specify the same amino acid C) It contains stop codons D) It reads in triplets

22. Which of the following is a 'stop' codon in the genetic code?

A) AUG B) UAA C) GGC D) CUU

23. The start codon, which also codes for Methionine, is typically:

A) UAA B) UAG C) AUG D) UGA

24. Erwin Chargaff's rules state that in DNA, the amount of Adenine is equal to the amount of Thymine, and the amount of Guanine is equal to the amount of Cytosine. This is known as:

A) Central dogma B) Semi-conservative replication C) Base pairing rules D) Chargaff's rules

25. What does the term 'semi-conservative replication' mean?

A) Each new DNA molecule consists of two completely new strands. B) Each new DNA molecule consists of one original strand and one newly synthesized strand. C) The original DNA molecule is completely broken down and rebuilt. D) Replication occurs only once per cell cycle.

26. In eukaryotes, transcription occurs in the:

A) Cytoplasm B) Ribosomes C) Nucleus D) Mitochondria

27. What is the function of the promoter region in a gene?

A) It signals the termination of transcription. B) It is the binding site for RNA polymerase. C) It codes for the protein product. D) It is involved in DNA replication.

28. What is the term for a non-coding sequence within a gene that is removed during RNA processing?

A) Exon B) Intron C) Codon D) Promoter

29. What is the term for a coding sequence within a gene that is retained in the mature mRNA?

A) Intron B) Exon C) Anticodon D) Terminator

30. Which molecule carries the genetic code from the nucleus to the cytoplasm in eukaryotes?

A) DNA B) tRNA C) rRNA D) mRNA

31. Ribosomes are composed of:

A) DNA and proteins B) RNA and proteins C) Only DNA D) Only proteins

32. The anticodon on tRNA is complementary to the:

A) DNA template strand B) DNA coding strand C) mRNA codon D) Antigen

33. How many different types of amino acids are commonly found in proteins?

A) 10 B) 20 C) 30 D) 40

34. The genetic code is nearly universal. Which of the following is an exception?

A) Mitochondrial DNA B) Bacterial DNA C) Viral DNA D) Plant DNA

35. What is the function of telomeres in eukaryotic chromosomes?

A) To initiate DNA replication B) To protect the ends of chromosomes from degradation C) To bind transcription factors D) To form the centromere

36. Which enzyme is responsible for adding nucleotides to the 3' end of a growing DNA strand?

A) Helicase B) Ligase C) DNA polymerase D) Primase

37. What is the term for the region of DNA where replication begins?

A) Origin of replication B) Terminator sequence C) Promoter D) Enhancer

38. In prokaryotes, where does transcription and translation occur?

A) Transcription in nucleus, translation in cytoplasm B) Transcription and translation in nucleus C) Transcription and translation in cytoplasm D) Transcription in cytoplasm, translation in nucleus

39. What is the role of a sigma factor in bacterial transcription?

A) To unwind the DNA double helix B) To terminate transcription C) To recognize and bind to the promoter region D) To ligate DNA fragments

40. The structure of DNA described by Watson and Crick was:

A) Single-stranded helix B) Double-stranded helix C) Triple-stranded helix D) Linear double strand

41. Which of the following is a pyrimidine base found in DNA?

A) Adenine B) Guanine C) Cytosine D) Adenine and Guanine

42. The antiparallel nature of DNA strands refers to:

A) The bases pairing in opposite directions B) The sugar-phosphate backbones running in opposite directions (5' to 3' and 3' to 5') C) The helical twist of the molecule D) The presence of hydrogen bonds

43. What is the primary function of DNA?

A) Protein synthesis B) Energy storage C) Carrying genetic information D) Catalyzing biochemical reactions

44. Which RNA molecule is involved in protein synthesis and has an anticodon loop?

A) mRNA B) rRNA C) tRNA D) snRNA

45. What is the process called when DNA is transcribed into RNA?

A) Translation B) Replication C) Transcription D) Reverse transcription

46. The genetic code specifies the sequence of:

A) Nucleotides in DNA B) Amino acids in proteins C) Bases in RNA D) Sugars in DNA

47. Which enzyme seals the nicks in the sugar-phosphate backbone of DNA during replication?

A) Helicase B) Primase C) DNA polymerase D) DNA ligase

48. What is the 'wobble' hypothesis in translation?

A) The third base of the codon can sometimes mismatch with the anticodon. B) The first base of the anticodon can pair with more than one base on the mRNA. C) The ribosome can move backwards along the mRNA. D) Amino acids can be added in reverse order.

49. The process of DNA replication is essential for:

A) Protein synthesis B) Cell division C) Energy production D) Waste removal

50. Which of the following is NOT a characteristic of the genetic code?

A) Universal B) Ambiguous C) Degenerate D) Non-overlapping

Molecular basis of inheritance - DNA structure replication transcription translation genetic code - Online Test

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