NEET Biology Molecular Basis of Inheritance MCQs Set 12

Download NEET MCQs for NEET Biology: Molecular Basis of Inheritance

Explore reliable objective questions for Molecular Basis of Inheritance tailored for NEET learners. Utilizing these Biology multiple-choice formats ensures thorough preparation and strengthens problem-solving speed for upcoming school assessments.

Chapter-wise Objective Questions: Molecular Basis of Inheritance

Navigate directly to the 50 objective questions for Molecular Basis of Inheritance using the digital viewer below. Each practice set includes verified answer keys, allowing students to instantly cross-check their work and identify areas requiring further revision.

Multiple Choice Questions

Question 1: In a polynucleotide chain, the end that carries a free phosphate group is the
(a) 3' end
(b) 5' end
(c) both ends
(d) neither end
Show Answer & Explanation

Answer: (b) 5' end

Explanation:
1. The 5' end has a free phosphate on the 5' carbon of the sugar, and the 3' end has a free 3'-OH.

Teacher's Note:
1. Chains are written 5' to 3'.

Question 2: 5-methyl uracil is another chemical name for
(a) thymine
(b) cytosine
(c) adenine
(d) guanine
Show Answer & Explanation

Answer: (a) thymine

Explanation:
1. Thymine is uracil with a methyl group at position 5.

Teacher's Note:
1. Thymine occurs in DNA; uracil in RNA.

Question 3: The approximately uniform distance between the two strands of the DNA double helix is maintained because
(a) two purines pair together
(b) two pyrimidines pair together
(c) phosphates pair with sugars
(d) each purine pairs with a pyrimidine
Show Answer & Explanation

Answer: (d) each purine pairs with a pyrimidine

Explanation:
1. Purine-pyrimidine pairing (A with T, G with C) keeps the helix diameter constant at about 2 nm.

Teacher's Note:
1. Hydrogen bonds hold the pairs.

Question 4: The flow of information from RNA to DNA is called
(a) translation
(b) transcription
(c) reverse transcription
(d) replication
Show Answer & Explanation

Answer: (c) reverse transcription

Explanation:
1. Retroviruses use reverse transcriptase to make DNA from an RNA template (Temin and Baltimore).

Teacher's Note:
1. The central dogma is DNA to RNA to protein, with this exception.

Question 5: Histones are rich in the basic amino acid residues
(a) aspartic acid and glutamic acid
(b) lysine and arginine
(c) glycine and alanine
(d) cysteine and methionine
Show Answer & Explanation

Answer: (b) lysine and arginine

Explanation:
1. Lysine and arginine carry positive charges that bind the negatively charged DNA.

Teacher's Note:
1. Histone octamer: H2A, H2B, H3, H4 (two each).

Question 6: A segment of DNA coding for one polypeptide is called a
(a) cistron
(b) codon
(c) operator
(d) replicon
Show Answer & Explanation

Answer: (a) cistron

Explanation:
1. A cistron is a DNA segment coding for a polypeptide chain.

Teacher's Note:
1. Monocistronic: one cistron per mRNA.

Question 7: In eukaryotes, hnRNA (the primary mRNA transcript) is transcribed by
(a) RNA polymerase I
(b) RNA polymerase III
(c) DNA polymerase
(d) RNA polymerase II
Show Answer & Explanation

Answer: (d) RNA polymerase II

Explanation:
1. RNA pol I makes rRNAs (28S, 18S, 5.8S), pol II makes hnRNA, and pol III makes tRNA, 5S rRNA and snRNAs.

Teacher's Note:
1. Remember I, II, III as rRNA, mRNA, tRNA.

Question 8: The scientist who suggested that the genetic code should be made of three nucleotides was
(a) Har Gobind Khorana
(b) Marshall Nirenberg
(c) George Gamow
(d) Francis Crick
Show Answer & Explanation

Answer: (c) George Gamow

Explanation:
1. Gamow reasoned that 4 bases taken three at a time give 64 codons, enough for 20 amino acids.

Teacher's Note:
1. Crick later gave experimental support with frame-shift mutants.

Question 9: Hershey and Chase labelled DNA and protein of bacteriophage with the radioactive isotopes
(a) 35S and 32P respectively
(b) 32P and 35S respectively
(c) 14C and 15N respectively
(d) 3H and 14C respectively
Show Answer & Explanation

Answer: (b) 32P and 35S respectively

Explanation:
1. DNA contains phosphorus but no sulphur, whereas protein contains sulphur but no phosphorus.

Teacher's Note:
1. Only 32P entered the bacteria, proving DNA is genetic material.

Question 10: Which of the following is NOT an essential property of genetic material?
(a) Complete immutability
(b) Replicability
(c) Stability
(d) Expressibility
Show Answer & Explanation

Answer: (a) Complete immutability

Explanation:
1. Genetic material must replicate, be stable, express itself as phenotype and be capable of mutation for evolution; so it is not absolutely immutable.

Teacher's Note:
1. Mutations provide variation.

Question 11: Meselson and Stahl used which technique to prove semi-conservative DNA replication?
(a) Paper chromatography
(b) X-ray diffraction
(c) Gel electrophoresis
(d) Caesium chloride density gradient centrifugation
Show Answer & Explanation

Answer: (d) Caesium chloride density gradient centrifugation

Explanation:
1. They grew E. coli in 15N medium, then transferred to 14N, and separated heavy and light DNA by CsCl density gradient centrifugation.

Teacher's Note:
1. Hybrid DNA was seen after the first generation.

Question 12: Most prokaryotic genes are
(a) monocistronic and split
(b) monocistronic and non-split
(c) polycistronic and non-split
(d) polycistronic and split
Show Answer & Explanation

Answer: (c) polycistronic and non-split

Explanation:
1. In bacteria genes are often arranged in operons giving polycistronic mRNA, and they lack introns.

Teacher's Note:
1. Most eukaryotic genes are monocistronic and split.

Question 13: The scientist who synthesised copolymers of nucleotides with defined sequences for deciphering the code was
(a) Severo Ochoa
(b) H. G. Khorana
(c) George Gamow
(d) F. Sanger
Show Answer & Explanation

Answer: (b) H. G. Khorana

Explanation:
1. Khorana chemically synthesised RNA with repeating sequences that helped decode the genetic code.

Teacher's Note:
1. Ochoa's enzyme made RNA without a template.

Question 14: Since more than one codon can code for the same amino acid, the genetic code is said to be
(a) degenerate
(b) ambiguous
(c) overlapping
(d) non-universal
Show Answer & Explanation

Answer: (a) degenerate

Explanation:
1. Degeneracy: 61 sense codons for 20 amino acids.

Teacher's Note:
1. Each codon, however, codes for only one amino acid so the code is unambiguous.

Question 15: A classical example of a point mutation is
(a) Down syndrome
(b) Turner syndrome
(c) albinism due to deletion of a chromosome
(d) sickle-cell anaemia
Show Answer & Explanation

Answer: (d) sickle-cell anaemia

Explanation:
1. Replacement of a single base (GAG to GUG) changes glutamic acid to valine in the beta chain of haemoglobin.

Teacher's Note:
1. Down syndrome is a chromosomal aberration.

Question 16: Insertion or deletion of one or two bases that changes the reading frame is called
(a) point mutation
(b) silent mutation
(c) frame-shift mutation
(d) missense mutation
Show Answer & Explanation

Answer: (c) frame-shift mutation

Explanation:
1. The reading frame is disturbed from the point of insertion or deletion, changing all later codons.

Teacher's Note:
1. Insertion of three bases keeps the frame.

Question 17: In three dimensions, tRNA looks like an
(a) clover leaf
(b) inverted L
(c) straight rod
(d) double helix
Show Answer & Explanation

Answer: (b) inverted L

Explanation:
1. The cloverleaf of 2-D diagrams folds into an inverted L-shape.

Teacher's Note:
1. The anticodon loop and the amino acid acceptor end are at opposite ends.

Question 18: Sequences in mRNA that are not translated and lie at the 5' and 3' ends are known as
(a) untranslated regions (UTRs)
(b) introns
(c) exons
(d) operators
Show Answer & Explanation

Answer: (a) untranslated regions (UTRs)

Explanation:
1. UTRs are required for efficient translation.

Teacher's Note:
1. They are present before the start codon and after the stop codon.

Question 19: The operon concept was proposed by
(a) Beadle and Tatum
(b) Hershey and Chase
(c) Meselson and Stahl
(d) Jacob and Monod
Show Answer & Explanation

Answer: (d) Jacob and Monod

Explanation:
1. Francois Jacob and Jacques Monod proposed the lac operon model of regulation in bacteria.

Teacher's Note:
1. They shared the 1965 Nobel prize with Lwoff.

Question 20: The i gene of the lac operon codes for the
(a) beta-galactosidase
(b) permease
(c) repressor
(d) transacetylase
Show Answer & Explanation

Answer: (c) repressor

Explanation:
1. The regulatory i gene produces a repressor protein that binds to the operator.

Teacher's Note:
1. The repressor is made all the time.

Question 21: The a gene of the lac operon codes for
(a) permease
(b) transacetylase
(c) beta-galactosidase
(d) repressor
Show Answer & Explanation

Answer: (b) transacetylase

Explanation:
1. z codes for beta-galactosidase, y for permease and a for transacetylase.

Teacher's Note:
1. Z-Y-A order in the operon.

Question 22: In the lac operon, lactose acts as the
(a) inducer
(b) repressor
(c) operator
(d) promoter
Show Answer & Explanation

Answer: (a) inducer

Explanation:
1. Lactose (allolactose) binds the repressor and inactivates it, permitting transcription.

Teacher's Note:
1. Regulation of lac operon by repressor is negative regulation.

Question 23: The beta-galactosidase enzyme encoded by the z gene mainly hydrolyses
(a) maltose into glucose
(b) sucrose into glucose and fructose
(c) starch into maltose
(d) lactose into galactose and glucose
Show Answer & Explanation

Answer: (d) lactose into galactose and glucose

Explanation:
1. Beta-galactosidase breaks the beta-galactoside lactose into its monosaccharides.

Teacher's Note:
1. Permease increases permeability of cell to lactose.

Question 24: The technique of DNA fingerprinting was initially developed by
(a) Frederick Sanger
(b) Kary Mullis
(c) Alec Jeffreys
(d) Hamilton Smith
Show Answer & Explanation

Answer: (c) Alec Jeffreys

Explanation:
1. Alec Jeffreys used variable repeats (VNTR) as probes.

Teacher's Note:
1. DNA fingerprinting depends on DNA polymorphism.

Question 25: VNTR belongs to the class of satellite DNA called
(a) micro-satellite
(b) mini-satellite
(c) macro-satellite
(d) telomeric DNA
Show Answer & Explanation

Answer: (b) mini-satellite

Explanation:
1. VNTR (variable number of tandem repeats) is a mini-satellite.

Teacher's Note:
1. Satellite DNA forms small peaks in density gradient.

Free study material for Biology

Download Chapter MCQs: NEET Biology Molecular Basis of Inheritance

NEET Biology Molecular Basis of Inheritance Objective Test Questions

Test your conceptual understanding of Molecular Basis of Inheritance with these targeted multiple-choice questions. Designed in alignment with the latest NEET curriculum for NEET Biology, these problem sets build accuracy and prepare students for objective exams.

NCERT-Aligned Objective Questions and Solutions

Cross-reference your completed choices with comprehensive NCERT solutions for NEET Biology to ensure absolute clarity across all sub-topics in this chapter.

Next Steps in Your Exam Preparation

Wrap up your chapter revision by testing your knowledge against standard question formats. Everything on our platform is provided free of charge.

FAQs

Where can I access latest NEET Biology Molecular Basis of Inheritance MCQs Set 12?

You can get most exhaustive NEET Biology Molecular Basis of Inheritance MCQs Set 12 for free on StudiesToday.com. These MCQs for NEET Biology are updated for the 2026-27 academic session as per NEET examination standards.

Are Assertion-Reasoning and Case-Study MCQs included in the Biology NEET material?

Yes, our NEET Biology Molecular Basis of Inheritance MCQs Set 12 include the latest type of questions, such as Assertion-Reasoning and Case-based MCQs. 50% of the NEET paper is now competency-based.

How do practicing Biology MCQs help in scoring full marks in NEET exams?

By solving our NEET Biology Molecular Basis of Inheritance MCQs Set 12, NEET students can improve their accuracy and speed which is important as objective questions provide a chance to secure 100% marks in the Biology.

Do you provide answers and explanations for NEET Biology Molecular Basis of Inheritance MCQs Set 12?

Yes, Biology MCQs for NEET have answer key and brief explanations to help students understand logic behind the correct option as its important for 2026 competency-focused NEET exams.

Can I practice these Biology NEET MCQs online?

Yes, you can also access online interactive tests for NEET Biology Molecular Basis of Inheritance MCQs Set 12 on StudiesToday.com as they provide instant answers and score to help you track your progress in Biology.