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Molecular Basis of Inheritance: Class-XII


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MCQs on Molecular Basis of Inheritance: Class-XII for NEET Practice


Match List-I with List-II regarding Nucleosome packaging.

List-I (Component)List-II (Description)
A. Histone OctamerI. Linker protein sealing DNA entry/exit
B. DNAII. Basic amino acids rich in Histones
C. H1 HistoneIII. Negatively charged polymer
D. Lysine and ArginineIV. Core of 8 molecules (H2A, H2B, H3, H4)

[Molecular-Basis-of-Inheritance] [class-xii ]

  • A-IV, B-III, C-I, D-II
  • A-IV, B-I, C-III, D-II
  • A-II, B-III, C-I, D-IV
  • A-III, B-IV, C-II, D-I
  • Correct Option: A  [ A-IV, B-III, C-I, D-II ]

    Remark: The Histone Octamer is the core of the nucleosome, formed by two copies each of H2A, H2B, H3, and H4. DNA is the negatively charged polymer (due to phosphate groups) that wraps around the octamer. H1 Histone is the linker histone that binds to the linker DNA where it enters and leaves the nucleosome. Lysine and Arginine are the positively charged basic amino acids abundant in histones.

Match List-I with List-II regarding Chromatin types.

List-I (Type)List-II (Property)
A. EuchromatinI. Densely packed, Transcriptionally Inactive
B. HeterochromatinII. Loosely packed, Transcriptionally Active
C. NucleosomeIII. Unit of chromatin ("Beads-on-string")
D. Non-histone Chromosomal ProteinsIV. Proteins for higher-level packaging

[Molecular-Basis-of-Inheritance] [class-xii ]

  • A-II, B-I, C-III, D-IV
  • A-I, B-II, C-III, D-IV
  • A-II, B-III, C-I, D-IV
  • A-III, B-I, C-II, D-IV
  • Correct Option: A  [ A-II, B-I, C-III, D-IV ]

    Remark: Euchromatin is loosely packed, stains lightly, and is transcriptionally active. Heterochromatin is densely packed, stains darkly, and is transcriptionally inactive. The Nucleosome is the repeating unit of chromatin, giving the "beads-on-string" appearance. Non-histone Chromosomal (NHC) proteins are required for the packaging of chromatin at higher levels.

Match List-I with List-II regarding the Hershey-Chase Experiment.

List-I (Component)List-II (Label/Role)
A. Radioactive Sulfur (S-35)I. Used to label DNA
B. Radioactive Phosphorus (P-32)II. Removal of viral coats (Agitation)
C. BlendingIII. Used to label Protein coat
D. CentrifugationIV. Separation of virus from bacteria based on density

[Molecular-Basis-of-Inheritance] [class-xii ]

  • A-III, B-I, C-II, D-IV
  • A-I, B-III, C-II, D-IV
  • A-III, B-II, C-I, D-IV
  • A-II, B-IV, C-III, D-I
  • Correct Option: A  [ A-III, B-I, C-II, D-IV ]

    Remark: Radioactive Sulfur (S-35) labels the protein coat because amino acids (Methionine, Cysteine) contain sulfur, but DNA does not. Radioactive Phosphorus (P-32) labels DNA because the backbone contains phosphates. Blending is the agitation step to shear off viral coats. Centrifugation separates the heavier bacterial pellet (containing DNA) from the lighter viral supernatant.

Match List-I with List-II regarding DNA Replication Enzymes.

List-I (Enzyme)List-II (Function)
A. HelicaseI. Relieves supercoiling/tension
B. Topoisomerase (DNA Gyrase)II. Synthesizes RNA primer
C. PrimaseIII. Unzips/Unwinds DNA helix
D. DNA LigaseIV. Joins Okazaki fragments (Molecular Glue)

[Molecular-Basis-of-Inheritance] [class-xii ]

  • A-III, B-I, C-II, D-IV
  • A-III, B-IV, C-I, D-II
  • A-I, B-III, C-II, D-IV
  • A-II, B-I, C-III, D-IV
  • Correct Option: A  [ A-III, B-I, C-II, D-IV ]

    Remark: Helicase unwinds the DNA double helix by breaking hydrogen bonds. Topoisomerase relieves the torsional strain/supercoiling ahead of the replication fork. Primase synthesizes the short RNA primer needed for DNA polymerase to start. DNA Ligase joins the discontinuous Okazaki fragments on the lagging strand.

Match List-I with List-II regarding Transcription Units.

List-I (Part)List-II (Characteristic)
A. PromoterI. Located at 5-prime end (upstream) of coding strand
B. TerminatorII. Strand with 3-prime to 5-prime polarity
C. Coding StrandIII. Located at 3-prime end (downstream) of coding strand
D. Template StrandIV. Sequence same as RNA (except T instead of U)

[Molecular-Basis-of-Inheritance] [class-xii ]

  • A-I, B-III, C-IV, D-II
  • A-III, B-I, C-IV, D-II
  • A-I, B-II, C-III, D-IV
  • A-IV, B-III, C-II, D-I
  • Correct Option: A  [ A-I, B-III, C-IV, D-II ]

    Remark: The Promoter is located upstream at the 5-prime end of the coding strand. The Terminator is downstream at the 3-prime end. The Coding Strand runs 5-prime to 3-prime and has the same sequence as RNA (T replacing U). The Template Strand has 3-prime to 5-prime polarity and guides the synthesis.

Match List-I with List-II regarding Eukaryotic RNA Polymerases.

List-I (Enzyme)List-II (Transcript)
A. RNA Polymerase II. hnRNA (Precursor of mRNA)
B. RNA Polymerase IIII. tRNA, 5S rRNA, snRNA
C. RNA Polymerase IIIIII. rRNAs (28S, 18S, 5.8S)

[Molecular-Basis-of-Inheritance] [class-xii ]

  • A-III, B-I, C-II
  • A-I, B-II, C-III
  • A-III, B-II, C-I
  • A-II, B-III, C-I
  • Correct Option: A  [ A-III, B-I, C-II ]

    Remark: In eukaryotes, RNA Polymerase I transcribes large rRNAs (28S, 18S, 5.8S). RNA Polymerase II transcribes hnRNA, which is processed into mRNA. RNA Polymerase III transcribes tRNA, 5S rRNA, and snRNAs. Mnemonic: I-rRNA, II-mRNA, III-tRNA (RMT).

Match List-I with List-II regarding RNA Processing.

List-I (Process)List-II (Details)
A. CappingI. Removal of Introns and joining of Exons
B. TailingII. Addition of Methyl Guanosine Triphosphate at 5-prime end
C. SplicingIII. Addition of Adenylate residues at 3-prime end
D. ExonsIV. Coding sequences that appear in mature RNA

[Molecular-Basis-of-Inheritance] [class-xii ]

  • A-II, B-III, C-I, D-IV
  • A-III, B-II, C-I, D-IV
  • A-II, B-I, C-III, D-IV
  • A-I, B-II, C-III, D-IV
  • Correct Option: A  [ A-II, B-III, C-I, D-IV ]

    Remark: Capping adds a 7-methylguanosine cap to the 5-prime end. Tailing adds a Poly-A tail (Adenylate residues) to the 3-prime end. Splicing removes non-coding Introns. Exons are the coding sequences retained in the mature mRNA.

Match List-I with List-II regarding Genetic Code properties.

List-I (Property)List-II (Explanation)
A. DegeneracyI. One codon codes for only one amino acid
B. UnambiguousII. Code is read continuously without punctuation
C. UniversalIII. One amino acid can be coded by multiple codons
D. Comma-lessIV. Code is nearly same in all organisms (bacteria to human)

[Molecular-Basis-of-Inheritance] [class-xii ]

  • A-III, B-I, C-IV, D-II
  • A-I, B-III, C-IV, D-II
  • A-III, B-II, C-IV, D-I
  • A-IV, B-I, C-II, D-III
  • Correct Option: A  [ A-III, B-I, C-IV, D-II ]

    Remark: Degeneracy means some amino acids are coded by more than one codon. Unambiguous means a codon codes for one specific amino acid only. Universal means the code is shared by almost all organisms. Comma-less means the code is read contiguously.

Match List-I with List-II regarding Translation.

List-I (Component)List-II (Function)
A. Aminoacyl-tRNA SynthetaseI. Formation of peptide bond (Ribozyme)
B. 23S rRNAII. Termination of translation
C. Release FactorIII. Charging of tRNA (Aminoacylation)
D. UTRIV. Required for efficient translation

[Molecular-Basis-of-Inheritance] [class-xii ]

  • A-III, B-I, C-II, D-IV
  • A-I, B-III, C-II, D-IV
  • A-III, B-II, C-I, D-IV
  • A-II, B-I, C-IV, D-III
  • Correct Option: A  [ A-III, B-I, C-II, D-IV ]

    Remark: Aminoacyl-tRNA synthetase charges tRNA with amino acids. 23S rRNA acts as a ribozyme (peptidyl transferase) in bacteria. Release factors bind to stop codons to end translation. UTRs (Untranslated Regions) improve the efficiency of translation.

Match List-I with List-II regarding Lac Operon genes.

List-I (Gene)List-II (Product)
A. i geneI. Beta-galactosidase
B. z geneII. Repressor Protein
C. y geneIII. Transacetylase
D. a geneIV. Permease

[Molecular-Basis-of-Inheritance] [class-xii ]

  • A-II, B-I, C-IV, D-III
  • A-II, B-IV, C-I, D-III
  • A-I, B-II, C-IV, D-III
  • A-III, B-I, C-II, D-IV
  • Correct Option: A  [ A-II, B-I, C-IV, D-III ]

    Remark: The i gene codes for the Repressor. The z gene codes for Beta-galactosidase (hydrolyzes lactose). The y gene codes for Permease (increases permeability). The a gene codes for Transacetylase.