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NEET • BIOLOGY • MOLECULAR BASIS OF INHERITANCE

Molecular basis of inheritance practice · Hard

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31 Hard

31 of 88

Understanding +4 | -1

The adapter molecules for tryptophan and first amino acid during polypeptide synthesis has anticodon sequence respectively

View answer and explanation

Correct option: B

ACC, UAC

Option B (ACC, UAC) is correct because the anticodon for tryptophan (UGG) is ACC, and the anticodon for methionine (AUG), the first amino acid, is UAC.

32 Hard

32 of 88

Understanding +4 | -1

Radioactive thymidene is fed to cells about to enter S-phase. It will make radioactive

View answer and explanation

Correct option: C

Both (1) and (2)

Option C is correct because radioactive thymidine, a DNA precursor, will be incorporated into both euchromatin and heterochromatin during S-phase replication.

33 Hard

33 of 88

Understanding +4 | -1

Peptidyl transferase activity

View answer and explanation

Correct option: B

Is required for protein synthesis

Option B (Is required for protein synthesis) is correct because peptidyl transferase activity, which is the formation of peptide bonds, is essential for protein synthesis.

34 Hard

34 of 88

Understanding +4 | -1

Assertion (A): Codon for methionine & tryptophan said to be degenerate.

Reason (R): Methionine and tryptophan amino acids coded by more than one codons.

View answer and explanation

Correct option: D

Both (A) and (R) are false

Option D (Both (A) and (R) are false) is correct because methionine and tryptophan are coded by only one codon each, so they are not degenerate.

35 Hard

35 of 88

Understanding +4 | -1

Read the following statements and select the correct ones w.r.t. DNA structure.
A. Two nucleotides are linked through

3^{\prime}-5^{\prime}

phosphodiester linkage.
B. Pyrimidine nucleosides have

1^{\prime}-1^{\prime}

linkage.
C. Base pairing confers stability of DNA helix.
D. Purines are heterocyclic, 6 membered single ring structures.

View answer and explanation

Correct option: C

All except D

Option C is correct because statements A, B, and C accurately describe aspects of DNA structure, while statement D incorrectly describes purines.

36 Hard

36 of 88

Remembering +4 | -1

Assertion (A): The sequencing of chromosome-1 was completed at last in May-2006.

Reason (R): Chromosome-1 in the longest chromosome with maximum number of genes.

View answer and explanation

Correct option: A

Both (A) & (R) are true and the (R) is the correct explanation of the (A)

Option A (Both (A) & (R) are true and the (R) is the correct explanation of the (A)) is correct because chromosome 1 was the last to be sequenced due to its length and high gene count.

37 Hard

37 of 88

Understanding +4 | -1

Assertion (A): Lactose is the substrate for the enzyme

\beta

-galactosidase & it regulates switching on & off the operon.

Reason (R): A very low level of expression of lac operon is always present in cell the time.

View answer and explanation

Correct option: B

Both (A) & (R) are true but the (R) is not the correct explanation of the (A)

Option B (Both (A) & (R) are true but the (R) is not the correct explanation of the (A)) is correct because lactose acts as an inducer and a low level of lac operon expression is always present, but these are independent facts.

38 Hard

38 of 88

Application +4 | -1

If the length of a DNA molecule is 1.1 metres, what will be the approximate number of base pairs?

View answer and explanation

Correct option: B

3.3 \times {10^9}{\kern 1pt} bp

Option B (

3.3 \times {10^9}{\kern 1pt} bp

) is correct because the number of base pairs is calculated by dividing the total length of DNA by the distance between two consecutive base pairs.

39 Hard

39 of 88

Remembering +4 | -1

Which one of the following is the correct statement?

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Correct option: A

\mathrm{CsCl}

is used in Meselson and Stahl experiment

Option A (

\mathrm{CsCl}

is used in Meselson and Stahl experiment) is correct because Cesium chloride (CsCl) density gradient centrifugation was used by Meselson and Stahl to separate DNA molecules of different densities.

40 Hard

40 of 88

Remembering +4 | -1

The concept of transforming principle was first established by _____ using the bacterium ______.

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Correct option: C

Fredrick Griffith, Streptococcus pneumoniae

Option C (Fredrick Griffith, Streptococcus pneumoniae) is correct because Fredrick Griffith first established the concept of the transforming principle using Streptococcus pneumoniae.

41 Hard

41 of 88

Remembering +4 | -1

Which of the following is most abundant in human DNA?

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Correct option: B

Non-coding DNA

Option B (Non-coding DNA) is correct because the majority of human DNA is non-coding, including introns, regulatory sequences, and repetitive sequences.

42 Hard

42 of 88

Remembering +4 | -1

Which of the following have ds DNA?

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Correct option: D

Both (1) and (2)

Option D (Both (1) and (2)) is correct because both bacteriophages and eukaryotes can have double-stranded DNA as their genetic material.

43 Hard

43 of 88

Understanding +4 | -1

In eukaryotes, functioning of which RNA polymerase provides a template for polypeptide synthesis

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Correct option: C

RNA polymerase II

Option C (RNA polymerase II) is correct because in eukaryotes, RNA polymerase II transcribes mRNA, which serves as the template for polypeptide synthesis (translation).

44 Hard

44 of 88

Remembering +4 | -1

In DNA, substitution of purine base with a pyrimidine bas or vice versa is called

View answer and explanation

Correct option: D

Transversion

Option D is correct because transversion is a type of point mutation where a purine base (A or G) is substituted with a pyrimidine base (C or T), or vice versa.

45 Hard

45 of 88

Remembering +4 | -1

RNA which carry amino acid from the cytoplasm to the ribosome is

View answer and explanation

Correct option: B

t-RNA

Option B is correct because tRNA carries amino acids from the cytoplasm to the ribosome.

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46 Hard

46 of 88

Application +4 | -1

How many amino acids will be coded by the mRNA sequence 5'-CCCUCAUAGUCAUAC-3', if one adenosine residue is inserted after every

12^{\text {th }}

nucleotide?

View answer and explanation

Correct option: C

Two amino acids

Option C (Two amino acids) is correct because after inserting adenosine, only two complete codons remain before a stop codon is encountered.

47 Hard

47 of 88

Understanding +4 | -1

DNA is a polymer of nucleotides are linked to each other by

3' - 5'

phosphodiester bond. To prevent polymerisation of nucleotides, which of the following modifications would you choose?

View answer and explanation

Correct option: B

Remove / Replace

3'\mathrm{OH}

group in deoxyribose

Option B is correct because the 3' OH group is essential for forming the phosphodiester bond during nucleotide addition; removing or replacing it would prevent polymerization.

48 Hard

48 of 88

Remembering +4 | -1

A transcription unit in DNA is defined primarily by the three regions in DNA and these are with respect to upstream and down stream end

View answer and explanation

Correct option: C

Promoter, Structural gene, Terminator

Option C (Promoter, Structural gene, Terminator) is correct because a transcription unit is defined by the promoter, structural gene, and terminator regions.

49 Hard

49 of 88

Understanding +4 | -1

Assertion: Enzymes required for DNA replication are efficient enzymes

Reason: They can polymerise large number of nucleotides in very short time.

View answer and explanation

Correct option: A

If both the assertion and the reason are true and the reason is a correct explanation of the assertion

Option A is correct because the enzymes involved in DNA replication are efficient, capable of polymerizing a large number of nucleotides quickly, making both the assertion and reason true, with the reason explaining the assertion.

50 Hard

50 of 88

Application +4 | -1

How many amino acids will be coded by the mRNA sequence –
5’CCCUCAUAGUCAUAC3’ if a adenosine residue is inserted after 12th nucleotide?

View answer and explanation

Correct option: C

2 amino acids

Option C (2 amino acids) is correct because the original sequence codes for 4 amino acids, and the insertion changes the reading frame such that the sequence now codes for 2 amino acids before encountering a stop codon.

51 Hard

51 of 88

Analyzing +4 | -1

Assertion (A): The presence of introns is reminiscent of antiquity & the process of splicing represents the dominance of RNA world.

Reason (R): The split gene arrangement represents an advanced feature of the genome.

View answer and explanation

Correct option: C

(A) is true but (R) is false

Option C ((A) is true but (R) is false) is correct because the presence of introns is considered an ancient feature, but the split gene arrangement is not necessarily an advanced feature.

52 Hard

52 of 88

Remembering +4 | -1

Which of the following is 9-membered double-ring structure?

View answer and explanation

Correct option: B

Guanine

Option B (Guanine) is correct because guanine is a purine, which has a 9-membered double-ring structure.

53 Hard

53 of 88

Analyzing +4 | -1

Assertion (A): Lac operator is present only in lac operon & it interact specifically with lac repressor only.

Reason (R): Each operon has its specific operator & specific repressor.

View answer and explanation

Correct option: A

Both (A) & (R) are true and the (R) is the correct explanation of the (A)

Option A (Both (A) & (R) are true and the (R) is the correct explanation of the (A)) is correct because the lac operator specifically interacts with the lac repressor, and this specificity is a general feature of operons.

54 Hard

54 of 88

Remembering +4 | -1

Okazaki fragments are formed during

View answer and explanation

Correct option: A

Replication of DNA

Option A (Replication of DNA) is correct because Okazaki fragments are formed during the discontinuous synthesis of the lagging strand in DNA replication.

55 Hard

55 of 88

Understanding +4 | -1

Other than DNA polymerase, which of the following enzymes involved in DNA synthesis?

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Correct option: D

All of these

Option D (All of these) is correct because Topoisomerase, Helicase, and RNA polymerase are all involved in DNA synthesis.

56 Hard

56 of 88

Understanding +4 | -1

‘Replication of DNA is semiconservative’
This is evident from

View answer and explanation

Correct option: B

Messelson and Stahl experiment on E.coli

Option B is correct because the Meselson and Stahl experiment on E.coli provided evidence for the semi-conservative nature of DNA replication.

57 Hard

57 of 88

Understanding +4 | -1

lac

operon system, which of the given gene receives the product of regulator gene?

View answer and explanation

Correct option: A

Operator gene

Option A (Operator gene) is correct because the product of the regulator gene (repressor protein) binds to the operator gene in the lac operon.

58 Hard

58 of 88

Understanding +4 | -1

Assertion (A): Gene regulation in prokaryotes is comparatively simple than eukaryotes.

Reason (R): In most of prokaryotic operons the genes present int the operon are needed together to function in the same or related metabolic pathway.

View answer and explanation

Correct option: A

Both (A) & (R) are true and the (R) is the correct explanation of the (A)

Option A (Both (A) & (R) are true and the (R) is the correct explanation of the (A)) is correct because prokaryotic gene regulation is simpler due to the organization of genes into operons that are coordinately regulated for related metabolic pathways.

59 Hard

59 of 88

Understanding +4 | -1

Which of the following would you expect to find in an inducible system?

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Correct option: A

A repressor protein, which is bound to DNA in absence of any other factor

Option A (A repressor protein, which is bound to DNA in absence of any other factor) is correct because in an inducible system, the repressor protein is normally bound to the DNA, preventing transcription, until an inducer binds to it and removes it.

60 Hard

60 of 88

Understanding +4 | -1

Assertion (A): Many non-human model organisms have also been sequenced.

Reason (R): Their sequences can be applied towards solving challenges in health care, agriculture, energy production etc.

View answer and explanation

Correct option: A

Both (A) & (R) are true and the (R) is the correct explanation of the (A)

Option A (Both (A) & (R) are true and the (R) is the correct explanation of the (A)) is correct because sequencing non-human model organisms helps solve health, agriculture, and energy challenges.

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