NEET Prep

Molecular Basis of Inheritance

51 NEET questions on Molecular Basis of Inheritance. A sample is shown below with full explanations; the rest are available free after signing up.

2026 22025 82024 62023 112022 72021 82020 42019 5
Molecular Basis of Inheritance2026hard

Q1.Which of the following statements about lac-operon is correct?

  • AGene i is constitutively expressedAnswer
  • BLactose activates repressor to bind to the operator
  • CGenes i, z, y and a share single common promoter
  • DGalactose can act as an inducer of lac operon

Explanation

The regulator gene i is transcribed continuously, so repressor protein is always available — that is what constitutive expression means. The others are wrong: lactose REMOVES the repressor from the operator rather than helping it bind; i has its own promoter separate from the z, y, a structural genes; and the inducer is allolactose, not galactose.

Source: NEET 2026 re-exam (21 June), Code 50, Q153

Molecular Basis of Inheritance2026medium

Q2.Which of the following enzymes synthesizes precursor mRNA?

  • ARNA polymerase I
  • BRNA polymerase IIAnswer
  • CRNA polymerase III
  • DDNA polymerase

Explanation

Eukaryotes divide the work between three RNA polymerases. RNA polymerase II transcribes hnRNA, the precursor of mRNA. RNA polymerase I makes rRNA and RNA polymerase III makes tRNA, 5S rRNA and snRNAs.

Source: NEET 2026 re-exam (21 June), Code 50, Q167

Molecular Basis of Inheritance2025medium

Q3.Given below are two statements. In the light of the above statements, choose the correct answer from the options given below.

  • Statement I: In the RNA world, RNA is considered the first genetic material evolved to carry out essential life processes; RNA acts as a genetic material and also as a catalyst for some important biochemical reactions in living systems, and being reactive, RNA is unstable.
  • Statement II: DNA evolved from RNA and is a more stable genetic material; its double helical strands being complementary, resist changes by evolving repairing mechanism.
  • ABoth statement I and statement II are correctAnswer
  • BBoth statement I and statement II are incorrect
  • CStatement I is correct but statement II is incorrect
  • DStatement I is incorrect but statement II is correct

Explanation

Both statements are correct and together they are the standard argument for the RNA world. RNA can both store information and act as a ribozyme, which is why it is proposed as the first genetic material, but the 2′-OH group makes it chemically reactive and short lived. DNA arose by reverse transcription from RNA, and because its two strands are complementary a damaged base can be repaired using the other strand as template.

Source: NEET 2025 (4 May), Code 45, Q96

Practise the full bank, free

1286 questions with worked explanations, timed mocks and a syllabus map that shows where you are weak.

Create a free account

Questions are reformatted from NEET previous year papers with original explanations and topic tagging. NEET Prep is not affiliated with the NEET examining body.