CBSE Class 12 Biology - Molecular Basis Of Inheritance

CBSE Basic Concepts for Class XII Biology -Molecular Basis Of Inheritance . Based on CBSE and CCE guidelines. The students should read these basic concepts to gain perfection which will help him to get more marks in CBSE examination.



1.Name the genetic material in TMV.

2.Write the scientific name of the plant on which Taylor et al performed their experiment.

3.What would be the proportion of light and hybrid density DNA molecules after 80 minutes of a single cell of E. coli growth?

4.When does DNA replicate in the cell cycle ?

5.Name the amino acids having only one codon.


1.What is meant by semiconservative nature of DNA replication?

2. What are the functions of DNA polymerase?

3. What is frame shift mutation ? Name the type of mutation that does not affect protein synthesis .

4.What are the untranslated regions (UTRs) ?

5.Briefly describe polymorphism.

6. What do you mean by phosphodiester bond?

Ans: The bond which is formed between the 3’-OH of one deoxyribonucleotide and 5’-phosphate residue of an adjacent deoxyribonucleotide.

7. What type of transcription is found in retrovirus? Name the enzyme.

Ans: in retrovirus the genetic information flows from RNA to DNA and is called reverse transcription while the enzyme involved is called reverse transcriptase.

8. What would happen if histones were to be mutated and made rich in amino acids aspartic acid and glutamic acid in place of basic amino acids such as lysine and arginine?

Ans: If histone proteins were rich in acidic amino acids instead of basic amino acids then they would not have any role in DNA packaging in eukaryotes as DNA is also negatively charged molecule. The

packaging of DNA around the nucleosome would not happen. Consequently, the chromatin fibre would

not be formed.

9. Explain what happens in frameshift mutation. Name one disease caused by the disorder.

Ans: Mutation in which addition/insertion or deletion of one or two bases changes the reading frame from the site of mutation is called frameshift mutation. It may result in polypeptide with different sequences of amino acids. Disease caused by frameshift mutation - sickle-cell anemia.

10. Comment on the utility of variability in number of tandem repeats during DNA fingerprinting.

Please refer to attached file for CBSE Class 12 Biology - Molecular Basis Of Inheritance

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