NCERT Exemplar Class 12 Biology Chapter 6 Solutions: Molecular Basis of Inheritance

NCERT Exemplar Class 12 Biology Solutions Chapter 6 – Molecular Basis of Inheritance will help you to revise the complete syllabus to score higher in exams. To give you an idea, this chapter of NCERT Exemplar Class 12 Biology Solutions Chapter 6 exhaustively covers all aspects of the chapter. You read this and you have a clear idea of what DNA, the genetic code, and gene expression are all about. NCERT exemplar solution will also help you to understand the molecular basis of inheritance alongside the structure of genetic materials (i.e. DNA, RNA) and their occurrence within the nucleus. The experts in the field explain the solutions very clearly and include all the basic concepts/theories and rules of biology.

NCERT Exemplar Class 12 Biology Solutions Chapter 6 – Molecular Basis of Inheritance have a total of 71 questions that are divided into 4 sections touching all the topics based on Chapter 6 – Molecular Basis of Inheritance. The questions are of various kinds which will help you get a complete revision with the help of numerical based questions, question banks, short and long type questions, objective type questions, and MCQs kind of questions exercises and worksheets related to genetics which are important from the CBSE board exam point of view.

Instasolv has created solutions to various NCERT exemplar solutions in unique and smooth steps that you can learn easily. By following the strategies of the professionals at Instasolv, you may better your grades in CBSE exams at the time and have an edge while taking various competitive exams like AIPMT, NEET and other graduate entrance exams.

Important Topics for NCERT Exemplar Class 12 Biology Solutions Chapter 6

  1. Nucleic acid: A complex organic substance present in living cells, especially DNA or RNA, whose molecules contain many nucleotides that bind to a long chain.
  2. DNA functions as the genetic material of most living things. RNA also functions as genetic material and in some organisms, such as some viruses; act as a messenger, an adapter, structure, and in some cases, a catalyst molecule.
  3. DNA – It is a long polymer of deoxyribonucleotides. A pair of nucleotides is also called base pairs. The length of DNA is usually defined as several nucleotides located there. Escherichia coli are 4.6 x 106 bp and the haploid content of human DNA is 3.3 × 109 bp.
  4. Polynucleotide chain structure: Nucleotides have three components. Nitrogen-based pentose sugars (ribose for RNA, deoxyribose for DNA) and phosphate groups. There are two types of nitrogenous bases: purines (adenine and guanine) and pyrimidines (cytosine, uracil, and thymine).
  5. In RNA, nucleotide buildup has an extra – OH bunch present at 2′- position in ribose and uracil is found at the spot of Thymine.
  6. Structure of DNA proposed by James Watson and Francis Crick: The double helix model for the structure of DNA — James Watson and   Francis Crick — based on Wilkin and Rosalind’s X-ray diffraction data, proposed this DNA model.
  7. The distinctive features of this model are:
  • a) The DNA backbone is made up of sugar-phosphate bond
  • b) The two circuits have antiparallel polarity. One is  5′-3 ‘and another one is  3′-5’.
  • c) The bases of the two strands are connected by an H bond. Adenine and thymine form a double hydrogen bond, and guanine and cytosine form a tritium bond. 
  • d) The two chains are folded with the right hand. The pitch of the helix is 3.4 nm, about 10 bp at each turn. 
  • e) The planes of one base pair are stacked on top of another base pair in a double helix to provide stability.
  • The central dogma in molecular biology proposed by Francis Crick, according to which there are flows of genetic information from DNA —–> RNA ——> Protein.

  • DNA helix packaging: Each nucleosome contains about 200 base pairs. Chromatin is the repeating unit of the nucleosome.

The characteristics of the genetic material are: 

  1. It must be able to produce its replica (replica).
  2.  It must be chemically and structurally stable. 
  3.  Must provide the scope for the slow changes (adaptation) required for evolution. 
  4.  It must be able to express itself in the form of ‘Mendelian characters.
  • DNA replication: Watson and Crick suggested that the two strands of DNA are distinct from each other and serve as a template for the synthesis of new complementary strands.
  • Mussels on and Stahls show experimental evidence of semi-conservative replication by growing E. coli in nutrient media containing radioactive 15N-labeled nitrogen salts (15NH4Cl).
  • DNA Transcription: Only one segment and one strand of DNA are copied to RNA. Adenine base pairs with uracil instead of thymine.

  1. Mutations are codon errors caused by nucleotide base changes. … For example, even if the codon GAA codon becomes GAG because of the degeneracy of the genetic code, the codon encodes the amino acid glutamic acid.
  2. Regulation of gene expression: Not all genes are required consistently. Genes that are sometimes only needed are called regulatory genes and function only when needed and remain inactive at other times. Such regulated genes must be “on” or “off” if a certain function is to start or stop.
  3. The main features of the human genome are:
  •  The human genome contains 3164.7 million nucleotide bases.
  •  The average gene has 3000 bases, but there are huge differences in size.
  •  Less than 2 percent of the genome code for a protein.
  •  Frequent sequencing forms the bulk of the human genome. 
  •  Repeat sequence is a sequence of DNA sequences that are repeated several times, sometimes up to 100,000 times. 
  • Chromosome 1 contains the largest number of genes (2968), and Y has the lowest number (231). 
  • Scientists have identified about 1.4 million sites where single-base DNA differences (SNPs – single nucleotide polymorphisms) occur in humans.
  • DNA fingerprinting is an extremely speedy approach to think about the DNA succession of any two people.

Discussion of Exercises of NCERT Exemplar Class 12 Biology Solutions Chapter 6 –Molecular Basis of Inheritance

  1. The first section of NCERT Exemplar Class 12 Biology Solutions Chapter 6 has 28 questions which are MCQs that are based on nucleotide structure, Watson and crick hypothesis, and chemical nature of template, Hershey and Chase experiment.
  2. The third section has 11 questions which are very short answer type questions that will help you to understand different terminologies including DNA fingerprinting, gene mutation, recombination of genes, gene expression regulatory system disorders related to a mutation in genes and genetic code.
  3. The fourth section has 23 questions which are short answer types that will ask you to compare different terms related to nucleotide structure.
  4. The fifth section has 9 questions which are long answer type questions that are based on explanation over human genome projects, PCR, Watson and crick experiment of DNA replication.
  5. The NCERT exemplar questions include the simplest quality problems that will test you in varying levels of difficulty on any given topic. Questions that are mentioned within the NCERT exemplar are of immense importance from CBSE’s point of view.

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NCERT Exemplar Class 12 Biology Solutions Chapter 6 – Molecular Basis of Inheritance by Instasolv expert incorporates all the significant subjects with point by point clarification that plans to assist students with understanding the ideas better. Experiencing the arrangements given on this page will assist you in knowing how to approach and take care of the issues.