NCERT CLASS 12 CHAPTER 6 MOLECULAR BASIS OF INHERITANCE QUESTIONS WITH
CORRECT ANSWERS LATEST UPDATE 2025/2026
transcription - Answers process of making RNA from DNA
genetic code that determines the sequences of amino acids in proteins
process of copying genetic information from one strand of the DNA into RNA
translation - Answers process of protein synthesis
length of DNA - Answers number of nucleotides (or a pair of nucleotide referred to as base pairs)
present in it
DNA - Answers First identified by Friedrich Meischer (1869)
- Meischer called it "Nuclein"
- acidic substance present in nucleus
long polymer of deoxyribonucleotides
characteristic of an organism
Bacteriophage φ ×174 - Answers 5386 nucleotides
Bacteriophage lambda - Answers 48502 base pairs (bp)
Escherichia coli - Answers 4.6 × 10^6 bp
haploid content of human DNA - Answers 3.3 × 10^9 bp
nucleotide - Answers 3 Parts
- nitrogenous base
- pentose sugar (ribose in RNA, and deoxyribose for DNA)
- phosphate group
- phosphate group is linked to OH of 5' C of a nucleoside through phosphoester linkage
nitrogenous bases - Answers - Purines
- Pyrimidines
- Linked to sugar moiety project from the backbone
Purines - Answers - Adenine
, - Guanine
Pyrimidines - Answers - Cytosine
- Uracil (RNA only)
- Thymine (DNA only)
nucleoside - Answers nitrogenous base is linked to the OH of 1' C pentose sugar through a N-
glycosidic linkage
Types of nucleoside - Answers adenosine or deoxyadenosine
guanosine or deoxyguanosine
cytidine or deoxycytidine
uridine or deoxythymidine
Dinucleotide - Answers 2 nucleotides are linked through 3'-5' phosphodiester linkage
polynucleotide chain - Answers Multiple nucleotides are linked through 3'-5' phosphodiester
linkage
3' -end of polynucleotide chain - Answers free OH of 3'C group
5'-end of polynucleotide chain - Answers free phosphate moiety at 5' -end of sugar
Backbone of a polynucleotide chain - Answers formed due to sugar and phosphates
Thymine - Answers 5-methyl uracil
RNA - Answers every nucleotide residue has an additional -OH group present at 2' -position in
the ribose
Double Helix model - Answers In 1953 James Watson and Francis Crick
based on the X-ray diffraction data produced by Maurice Wilkins and Rosalind Franklin
Chargaff's Rule - Answers Double stranded DNA, the ratios between Adenine and Thymine and
Guanine and Cytosine are constant, equal to 1
A=T and G=C
Adenine - Answers forms 2 hydrogen bonds with Thymine
from opposite strand and vice-versa
Guanine - Answers - bonded with Cytosine with 3 H-bonds
CORRECT ANSWERS LATEST UPDATE 2025/2026
transcription - Answers process of making RNA from DNA
genetic code that determines the sequences of amino acids in proteins
process of copying genetic information from one strand of the DNA into RNA
translation - Answers process of protein synthesis
length of DNA - Answers number of nucleotides (or a pair of nucleotide referred to as base pairs)
present in it
DNA - Answers First identified by Friedrich Meischer (1869)
- Meischer called it "Nuclein"
- acidic substance present in nucleus
long polymer of deoxyribonucleotides
characteristic of an organism
Bacteriophage φ ×174 - Answers 5386 nucleotides
Bacteriophage lambda - Answers 48502 base pairs (bp)
Escherichia coli - Answers 4.6 × 10^6 bp
haploid content of human DNA - Answers 3.3 × 10^9 bp
nucleotide - Answers 3 Parts
- nitrogenous base
- pentose sugar (ribose in RNA, and deoxyribose for DNA)
- phosphate group
- phosphate group is linked to OH of 5' C of a nucleoside through phosphoester linkage
nitrogenous bases - Answers - Purines
- Pyrimidines
- Linked to sugar moiety project from the backbone
Purines - Answers - Adenine
, - Guanine
Pyrimidines - Answers - Cytosine
- Uracil (RNA only)
- Thymine (DNA only)
nucleoside - Answers nitrogenous base is linked to the OH of 1' C pentose sugar through a N-
glycosidic linkage
Types of nucleoside - Answers adenosine or deoxyadenosine
guanosine or deoxyguanosine
cytidine or deoxycytidine
uridine or deoxythymidine
Dinucleotide - Answers 2 nucleotides are linked through 3'-5' phosphodiester linkage
polynucleotide chain - Answers Multiple nucleotides are linked through 3'-5' phosphodiester
linkage
3' -end of polynucleotide chain - Answers free OH of 3'C group
5'-end of polynucleotide chain - Answers free phosphate moiety at 5' -end of sugar
Backbone of a polynucleotide chain - Answers formed due to sugar and phosphates
Thymine - Answers 5-methyl uracil
RNA - Answers every nucleotide residue has an additional -OH group present at 2' -position in
the ribose
Double Helix model - Answers In 1953 James Watson and Francis Crick
based on the X-ray diffraction data produced by Maurice Wilkins and Rosalind Franklin
Chargaff's Rule - Answers Double stranded DNA, the ratios between Adenine and Thymine and
Guanine and Cytosine are constant, equal to 1
A=T and G=C
Adenine - Answers forms 2 hydrogen bonds with Thymine
from opposite strand and vice-versa
Guanine - Answers - bonded with Cytosine with 3 H-bonds
