Class 12 Biology Chapter 6 Molecular Basis of Inheritance

Class 12 Biology Chapter 6 Molecular Basis of Inheritance The answer to each chapter is provided in the list so that you can easily browse through different chapters Assam Board HS 2nd Year Biology Chapter 6 Molecular Basis of Inheritance Question Answer.

Class 12 Biology Chapter 6 Molecular Basis of Inheritance

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Also, you can read the SCERT book online in these sections Solutions by Expert Teachers as per SCERT (CBSE) Book guidelines. These solutions are part of SCERT All Subject Solutions. Here we have given Assam Board Class 12 Biology Chapter 6 Molecular Basis of Inheritance Solutions for All Subjects, You can practice these here.

Molecular Basis of Inheritance

Chapter – 6


Very Short Answer Type Questions

(A) . Fill in the blanks :

Q.1. In DNA is a long polymer of ___ 

Ans : Nucleotide. 

Q.2. Uracil is present in ____

Ans : RNA. 

Q.3. Purine and pyrimidine are collectively known as____

Ans : Nitrogenous base.

Q.4. The distance between two consecutive base pairs is _____

Ans : 0.34 A°.

Q.5. The chromatin that is more densely packed and stains dark is called ____

Ans : Hetero chromatin. 

Q.6. DNA replication is termed as _____ 

Ans : Semiconservative. 

Q.7. The DNAM2- dependent DNA polymerases catalyse polymerization in _____ direction.

Ans : 5’→3′. 

Q.8. A gene is defined as the ___ unit of inheritance. 

Ans : Fundamental. 

Q.9. ____ is a segment of DNA coding for a polypeptide. 

Ans : Cistron. 

Q.10. AUG codes for ____

Ans : Methionine. 

Q.11. refers to the process of polymerization of amino acids to form a _____ 

Ans : Translation Polypeptide. 

Q.12. The ____ codes for the repressor in lac operon. 

Ans : Gene-i 

Q.13. Human genome project gave rise to a new area in biology called ___ 

Ans : Bioinformaties. 

Q.14. Regulation of lac operon by repressor is referred to as _____

Ans : Regulatory gene. 

Q.15. ____ arises due to mutation. 

Ans : Abnormal variation. 

Q.16. _____ and terminator segments flank the structural gene. 

Ans : Initiation. 

Q.17. An mRNA has some additional sequences that are not translated and are referred as _____

Ans : Termination codon. 

Q.18. During transcription RNA polymerase binds to____ 

Ans : Promoter. 

(B). True or False (1 mark) : 

Q.1. Central Dogma was proposed Watson. 

Ans : False. 

Q.2. RNases are RNA digesting enzymes. 

Ans : True. 

Q.3. DNA duplication is semiconservative. 

Ans : True. 

Q.4. The process of formation of DNA from RNA is called transcription.

Ans : False.

Q.5. The discontinuously synthesized fragments are joined by the enzyme DNA polymerase. 

Ans : True.

(C). Very short answer questions (1 mark) : 

Q.1. What is satellite DNA? 

Ans : It has been reported that heterochromatin contains certain polygenes to transcribe r RNA, m RNA and t RNA. Its DNA is formed of repeated polynucleotide sequences each being formed of about 300 nucleotides and is called satellite DNA or repetitive or redundant DNA. 

Q.2. What is Central Dogma? 

Ans : The process of protein synthesis involves one of the central dogma of molecular biology. According to this, genetic information flows from nucleic acid to protein, the flow of information takes place from DNA to RNA (m RNA) and from RNA to protein.

What is Central Dogma

Q.3. Define autoradiography? 

Ans : The mechanism of production of an autoradiogram by exposing photographic film to a radioactive substance in close proximity to the film. 

Q.4. What is an inducer in lac operon? 

Ans : All the genes present on a chromosome are not expressed simultaneously. The cell permits the expression of few genes at a time thus maintaining its economy. Inducible genes are the genes which remain inactive or repressed in a cell and can be activated when a certain substrate is to be metabolised. The phenomenon of action of these genes is called induction and metabolite is called inducer. 

A lac operon is defined as several genes operating in random, all controlled by a common structural gene having repressor, promoter and operator. All these genes are essential for metabolism of lactose. Only presence of lactose can switches on the operon for synthesis of enzyme inside the cell and hence it is termed as inducer lac operon.

Q.5. Name the bacteria used by Griffith for his transformation experiment. 

Ans : Streptococcus Pneumoniae.

Q.6. Who proved that DNA in chromosomes also replicate semiconservatively? 

Ans : Mathew Messelson and Franklin stahl. 

Q.7. How many structural genes are present in lac operon? 

Ans : Three Lac – z, Lac Y and Lac – A. 

Q.8. What is translation? 

Ans : Translation refers to a process of polymerization of amino acids to form a polypeptide order and sequence of amino acid are defined by the sequence of base is the mRNA. The amino acids are joined by a bond called peptide bend. 

Q.9. What is an intron? 

Ans : In some viruses, the DNA sequence coding for polypeptide do not remain continuously but are split into several pieces. These spit genes are called introm. 

Q.10. What is an exon?

Ans : DNA codes for mRNA, but complete sequence of DNA is not found in mRNA. The sequences of DNA found in mRNA are known as exon. 

Q.11. What are the three major types of RNAS present in bacteria. 

Ans : The three types of RNA are : mRNA, tRNA and rRNA. 

Q.12. Name the enzyme used to catalyse the polymerization of deoxynucleotides. 

Ans : DNA polymerase.

Q.13. Name the enzyme that joins the discontinuous fragments of DNA. 

Ans : Ligase. 

Q.14. Who proposed the semiconservative DNA replication. 

Ans : Methew Messelson and Franklin Stahl.

Q.15. How many bases code for an amino acid. 

Ans : Three. 

Q.16. Give the site of protein synthesis. 

Ans : Ribosome.

Q.17. What is the function of tRNA? 

Ans : tRNA carry the amino acids to the ribosome according to the message carried by mRNA. 

Q.18. Who proposed the operon model? 

Ans : Francis Jacob and Jacques Monod. 

Q.19. What is a bacteriophage? 

Ans : The virus which kills bacteria.

Q.20. What is a euchromatin? 

Ans : Chromatin of nucleus which stain positively with the DNA specific stain indicating the concentration of DNA is called euchromatin. 

Q.21. Define chromatin. 

Ans : DNA and histone protein together is called chromatin. 

Q.22. Give the definition of nucleosome. 

Ans : Nucleosome is a structure formed by wrapping of Histone Octomer by negatively changed DNA. 

Q.23. Which base triplet code for the amino acid phenylalanine? 

Ans : UUU UUC. 

Q.24. Name three nonsense codon. 


Q.25. What are the hosts for cloning DNA fragments. 

Ans : Ribosomes. 

Q.26. What are exons? 

Ans : DNA codes for in RNA but complete sequence of DNA is not found in m RNA. The sequences of DNA found in m RNA are known as exons. The coding sequences in eukaryotic genes are called as exons.

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