Class 12 Biology Case Study of Chapter 6 Molecular Basis of Inheritance

In Class 12 Boards there will be Case studies and Passage Based Questions will be asked, So practice these types of questions. Study Rate is always there to help you. Free PDF Downloads of CBSE Class 12 Biology Chapter 6 Molecular Basis of Inheritance Case Study and Passage Based Questions with Answers were Prepared Based on the Latest Exam Pattern. Students can solve Class 12 Biology Case Study Questions Molecular Basis of Inheritance to know their preparation level.

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In CBSE Class 12 Biology Paper, There will be a few questions based on case studies and passage-based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.

Molecular Basis of Inheritance Case Study Questions With Answers

Here, we have provided case-based/passage-based questions for Class 12 Biology Chapter 6 Molecular Basis of Inheritance

Case Study/Passage-Based Questions

Case Study 1: In prokaryotes, DNA is circular and present in the cytoplasm but in eukaryotes, DNA is linear and mainly confined to the nucleus. DNA or deoxyribonucleic acid is a long polymer of nucleotides. In 1953, the first correct double helical structure of DNA was worked out by Watson and Crick. Based on the X-ray diffraction data produced by Maurice Wilkins and Rosalind Franklin. It is composed of three components, i.e., A phosphate group, deoxyribose sugar, and a nitrogenous base. Different forms of DNA are B-DNA, Z-DNA, A-DNA, C-DNA, and D-DNA.


(i) Name the linkage present between the nitrogen base and pentose sugar in DNA.

(a) Phosphodiester bond(b) Glycosidic bond(c) Hydrogen bond(d) None of these

Answer: (b) Glycosidic bond


(ii) The double helix structure of DNA was proposed by

(a) James Watson and Francis Crick(b) Earwin Chargaff(c) Federick Griffith(d) Hershey and Chase

Answer: (a) James Watson and Francis Crick


(iii) The double chain of B-DNA is coiled in a helical fashion. The spiral twisting of the B-DNA duplex produces

(a) right and left part(b) major and minor grooves(c) upper and lower sides(d) linear and circular part.

Answer: (b) major and minor grooves


(iv) Assertion: The two strands of DNA helix have a uniform distance between them.
Reason: A large-sized purine is always paired opposite to a small-sized pyrimidine.

(a) Both assertion and reason are true and
reason is the correct explanation of assertion.
(b) Both assertion and reason are true but
reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.(d) Both assertion and reason are false.

Answer: (a) Both assertion and reason are true and reason is the correct explanation of assertion


 (v) Which of the following describes the structure of B-DNA?

Polynucleotide chainsNumber of base pairs per complete turn of helix
(a) Parallel5
(b) Anti-parallel10
(c) Parallel15
(d) Anti-parallel20

Answer: (b)


Case Study 2: The process of translation requires the transfer of genetic information from a polymer of nucleotides to synthesize a polymer of amino acids. The relationship between the sequence of amino acids in a polypeptide and the nucleotide sequence of DNA or mRNA is called genetic code. George Gamow suggested that in order to code for all the 20 amino acids, code should be made up of three nucleotides.

What is the process by which a polymer of nucleotides is used to synthesize a polymer of amino acids?
A) Replication
B) Transcription
C) Translation
D) Mutation

Answer: C


What is the relationship between the sequence of amino acids in a polypeptide and the nucleotide sequence of DNA or mRNA known as?
A) Genetic Translation
B) Genetic Mutation
C) Genetic Replication
D) Genetic Code

Answer: D


Who suggested that the genetic code should be made up of three nucleotides?
A) James Watson
B) Francis Crick
C) George Gamow
D) Rosalind Franklin

Answer: C


How many nucleotides are required to code for one amino acid in the genetic code?
A) One
B) Two
C) Three
D) Four

Answer: C


What is the main reason that three nucleotides are used to code for each amino acid?
A) To ensure replication accuracy
B) To allow for more combinations and code for all 20 amino acids
C) To facilitate faster transcription
D) To prevent mutations

Answer: B


Which of the following molecules carries the genetic information from DNA to the ribosome for translation?
A) tRNA
B) rRNA
C) mRNA
D) DNA

Answer: C


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