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Molecular Basis of Inheritance: MCQ Test

Test your comprehensive knowledge of DNA structure, replication, transcription, genetic code, translation, gene regulation, the Human Genome Project, and DNA fingerprinting with these challenging multiple-choice questions.

Test Your Knowledge

Showing questions 41 - 60 of 169

41. Which of the following is NOT a criterion for a molecule to act as a genetic material?

It should be able to generate its replica (Replication)
It should be highly reactive
It should provide scope for slow changes (mutation) that are required for evolution
It should be able to express itself in the form of 'Mendelian Characters’

A molecule that can act as a genetic material must fulfill criteria including being able to generate its replica, being stable chemically and structurally, providing scope for slow changes, and being able to express itself. Reactivity is not listed as a positive criterion [29].

42. What chemical feature makes RNA less stable and easily degradable compared to DNA?

Presence of adenine
Absence of thymine
Presence of a 2'-OH group at every nucleotide
Double-stranded structure

Further, 2'-OH group present at every nucleotide in RNA is a reactive group and makes RNA labile and easily degradable. RNA is also now known to be catalytic, hence reactive [30].

43. The presence of thymine at the place of uracil in DNA confers what to DNA?

Increased reactivity
Decreased stability
Additional stability
No significant effect

In fact, the presence of thymine at the place of uracil also confers additional stability to DNA [31].

44. Between DNA and RNA, which mutates at a faster rate, and what is a consequence of this?

DNA, leading to faster evolution in DNA viruses
RNA, leading to faster evolution in RNA viruses
Both mutate at the same rate
Neither mutates

Both DNA and RNA are able to mutate. In fact, RNA being unstable, mutate at a faster rate. Consequently, viruses having RNA genome and having shorter life span mutate and evolve faster [31].

45. Which nucleic acid can directly code for the synthesis of proteins, and which is dependent on the other for protein synthesis?

DNA can directly code; RNA is dependent.
RNA can directly code; DNA is dependent.
Both can directly code.
Neither can directly code.

RNA can directly code for the synthesis of proteins, hence can easily express the characters. DNA, however, is dependent on RNA for synthesis of proteins [32].

46. Which molecule is preferred for the storage of genetic information, and which is better for its transmission?

DNA for storage, RNA for transmission
RNA for storage, DNA for transmission
Both for storage, neither for transmission
Both for transmission, neither for storage

Both RNA and DNA can function as genetic material, but DNA being more stable is preferred for storage of genetic information. For the transmission of genetic information, RNA is better [32].

47. According to the 'RNA World' hypothesis, which was the first genetic material?

Protein
DNA
RNA
Lipid

RNA was the first genetic material [33].

48. RNA used to act as a genetic material and also as a catalyst for important biochemical reactions. What are RNA catalysts called?

Enzymes
Ribozymes
Holoenzymes
Coenzymes

There are some important biochemical reactions in living systems that are catalysed by RNA catalysts and not by protein enzymes [33]. One of the rRNA acts as a catalyst for peptide bond formation, which is an example of RNA enzyme (ribozyme) [34].

49. Why did DNA evolve from RNA?

To become less stable
To become more reactive
Due to chemical modifications that make it more stable
To lose its catalytic activity

DNA has evolved from RNA with chemical modifications that make it more stable [35].

50. Watson and Crick immediately proposed what scheme for DNA replication upon discovering its double helical structure?

Conservative DNA replication
Dispersive DNA replication
Semiconservative DNA replication
Non-conservative DNA replication

Watson and Crick had immediately proposed a scheme for replication of DNA, which was termed as semiconservative DNA replication [35, 36].

51. In semiconservative DNA replication, after replication, each new DNA molecule would have what composition?

Both newly synthesised strands
Both parental strands
One parental and one newly synthesised strand
A mix of parental and new segments on both strands

After the completion of replication, each DNA molecule would have one parental and one newly synthesised strand [36].

52. Who performed the experiment in 1958 that unequivocally proved DNA replicates semiconservatively in *Escherichia coli*?

James Watson and Francis Crick
Matthew Meselson and Franklin Stahl
Alfred Hershey and Martha Chase
Frederick Griffith

Matthew Meselson and Franklin Stahl performed the experiment in 1958 which proved that DNA replicates semiconservatively [37].

53. In Meselson and Stahl's experiment, what heavy isotope of nitrogen was used to label the DNA?

They grew E. coli in a medium containing 15NH4Cl (15N is the heavy isotope of nitrogen) as the only nitrogen source for many generations [37].

54. After one generation of transfer from 15N to 14N medium, what was the density of the extracted DNA in Meselson and Stahl's experiment?

Heavy
Light
Hybrid or intermediate
Very light

The DNA that was extracted from the culture one generation after the transfer from 15N to 14N medium had a hybrid or intermediate density [38].

55. After another generation (second generation) in 14N medium, what was the composition of the DNA extracted in Meselson and Stahl's experiment?

All hybrid DNA
All light DNA
Equal amounts of hybrid DNA and light DNA
Equal amounts of heavy DNA and light DNA

DNA extracted from the culture after another generation was composed of equal amounts of this hybrid DNA and of ‘light’ DNA [39].

56. Which scientists performed similar experiments using radioactive thymidine on *Vicia faba* to prove semiconservative replication in chromosomes of higher organisms?

Watson and Crick
Meselson and Stahl
Taylor and colleagues
Hershey and Chase

Very similar experiments involving use of radioactive thymidine to detect distribution of newly synthesised DNA in the chromosomes was performed on *Vicia faba* (faba beans) by Taylor and colleagues in 1958 [39].

57. What is the main enzyme referred to as that catalyses the polymerisation of deoxynucleotides using a DNA template during replication?

RNA polymerase
DNA ligase
DNA-dependent DNA polymerase
Helicase

The main enzyme is referred to as DNA-dependent DNA polymerase, since it uses a DNA template to catalyse the polymerisation of deoxynucleotides [40].

58. E. coli completes the process of replication within 18 minutes, meaning the average rate of polymerisation is approximately how many base pairs per second?

100 bp per second
500 bp per second
2000 bp per second
10000 bp per second

E. coli that has only 4.6 ×10^6 bp, completes the process of replication within 18 minutes; that means the average rate of polymerisation has to be approximately 2000 bp per second [40, 41].

59. Deoxyribonucleoside triphosphates serve what dual purposes in DNA replication?

Act as templates and provide energy
Act as substrates and provide energy
Act as catalysts and provide energy
Act as primers and provide energy

Deoxyribonucleoside triphosphates serve dual purposes. In addition to acting as substrates, they provide energy for the polymerisation reaction [41].

60. Why does replication occur within a small opening of the DNA helix, referred to as the replication fork?

Due to low energy requirement
Due to the catalytic activity of DNA ligase
Due to very high energy requirement to separate the entire length
Due to the action of RNA polymerase

For long DNA molecules, since the two strands of DNA cannot be separated in its entire length (due to very high energy requirement), the replication occurs within a small opening of the DNA helix, referred to as replication fork [42].

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Genetics: Principles of Inheritance and Variation MCQ Test

Evolution: MCQ Test

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