Free practice › Class 12 › Biology › Chapter 5
Molecular Basis of Inheritance — NEET MCQs with answers
The molecular basis of inheritance centres on DNA as the genetic material - Griffith's experiment revealed a 'transforming principle', and Hershey and Chase gave the unequivocal proof - whose double-helical structure (Watson and Crick, 1953) underlies semiconservative replication, shown by Meselson and Stahl. Genetic information flows from DNA to RNA (transcription) to protein (translation) per the central dogma; the genetic code is triplet, degenerate, read contiguously and nearly universal. Gene expression is regulated, as in the lac operon of bacteria; the Human Genome Project found the human genome to contain 3164.7 million bp, and DNA fingerprinting uses polymorphism in repetitive DNA for identification.
Topics in this chapter
- 5.1 The DNA
- 5.2 The Search for Genetic Material
- 5.3 RNA World
- 5.4 Replication
- 5.5 Transcription
- 5.6 Genetic Code
- 5.7 Translation
- 5.8 Regulation of Gene Expression
- 5.9 Human Genome Project
- 5.10 DNA Fingerprinting
Free practice questions
The transfer of separated DNA fragments from the gel to a synthetic membrane in DNA fingerprinting is technically called:
- A. Northern blotting
- B. Western blotting
- C. Southern blotting
- D. Eastern blotting
Show answer
Answer: C — NCERT states the technique involved Southern blot hybridisation; the transfer (blotting) of DNA fragments to a membrane is Southern blotting.
NCERT Class 12 Biology · Ch 5 · 5.10 DNA Fingerprinting
In the lac operon, the 'i' gene codes for which product?
- A. Beta-galactosidase
- B. Repressor
- C. Transacetylase
- D. Permease
Show answer
Answer: B — NCERT clearly states the i gene codes for the repressor of the lac operon. The term 'i' is derived from the word inhibitor, not inducer.
NCERT Class 12 Biology · Ch 5 · 5.8 Regulation of Gene Expression
The two polynucleotide chains of a DNA molecule have:
- A. Parallel polarity
- B. Identical sequences
- C. No fixed polarity
- D. Anti-parallel polarity
Show answer
Answer: D — The two chains have anti-parallel polarity - if one chain has the polarity 5'to3', the other has 3'to5'.
NCERT Class 12 Biology · Ch 5 · 5.1 The DNA
In the Hershey-Chase experiment, bacteria infected with viruses carrying radioactive protein (35S) were:
- A. radioactive only after blending
- B. not radioactive, showing protein did not enter
- C. radioactive, showing protein entered
- D. killed instantly
Show answer
Answer: B — NCERT: Bacteria infected with viruses that had radioactive proteins were not radioactive, indicating that proteins did not enter the bacteria from the viruses.
NCERT Class 12 Biology · Ch 5 · 5.2 The Search for Genetic Material
Which of the following best describes why deoxyribonucleoside triphosphates are NOT the molecules used to activate amino acids in translation?
- A. Amino acids are activated using the release factor
- B. Amino acids are activated using DNA ligase
- C. Amino acids do not require any activation
- D. Amino acids are activated using ATP, not deoxyribonucleoside triphosphates
Show answer
Answer: D — NCERT specifies that in translation amino acids are activated in the presence of ATP (not deoxyribonucleoside triphosphates) and linked to cognate tRNA during charging.
NCERT Class 12 Biology · Ch 5 · 5.7 Translation
Approximately how many locations of single-base DNA differences (SNPs) have scientists identified in humans?
- A. About 3164.7 million
- B. About 1.4 million
- C. About 30,000
- D. About 2.4 million
Show answer
Answer: B — NCERT salient feature (ix): Scientists have identified about 1.4 million locations where single-base DNA differences (SNPs) occur in humans.
NCERT Class 12 Biology · Ch 5 · 5.9.1 Salient Features
It is the presence of a promoter in a transcription unit that also defines:
- A. The poly-A tail length
- B. The number of exons
- C. The template and coding strands
- D. The site of splicing
Show answer
Answer: C — NCERT: 'it is the presence of a promoter in a transcription unit that also defines the template and coding strands.'
NCERT Class 12 Biology · Ch 5 · 5.5.1 Transcription Unit
During the deciphering of the code, homopolymers and copolymers of RNA with defined bases were used. Whose method produced these?
- A. George Gamow
- B. Marshall Nirenberg
- C. Francis Crick
- D. Har Gobind Khorana
Show answer
Answer: D — Har Gobind Khorana's chemical method was instrumental in synthesising RNA molecules with defined combinations of bases — homopolymers and copolymers.
NCERT Class 12 Biology · Ch 5 · 5.6 Genetic Code
There is now enough evidence that essential life processes evolved around RNA. Which set of processes does NCERT cite as examples?
- A. Digestion, absorption and excretion
- B. Mitosis, meiosis and binary fission
- C. Metabolism, translation and splicing
- D. Photosynthesis, respiration and fermentation
Show answer
Answer: C — NCERT: 'essential life processes (such as metabolism, translation, splicing, etc.), evolved around RNA.' These three processes are the examples given.
NCERT Class 12 Biology · Ch 5 · 5.3 RNA World
Semiconservative replication of DNA in chromosomes was demonstrated using radioactive thymidine in which plant?
- A. Arabidopsis thaliana
- B. Pisum sativum
- C. Vicia faba (faba bean)
- D. Zea mays
Show answer
Answer: C — NCERT: experiments using radioactive thymidine were performed on Vicia faba (faba beans) by Taylor and colleagues in 1958.
NCERT Class 12 Biology · Ch 5 · 5.4 Replication
Practise all 651 questions of Molecular Basis of Inheritance in timed NEET tests
+4/−1 marking like the real exam · see which topics cost you marks · notes, XP and leaderboards
Start your free trial →