NCERT Exemplar Class 12 Biology Chapter 5 Solutions: Principles of Inheritance and Variation

NCERT Exemplar Class 12 Biology Solutions Chapter 5- Principles of Inheritance and Variation will help you to revise the complete syllabus to score higher in exams. This chapter of NCERT Exemplar Class 12 Biology Solutions Chapter 5 will talk about various Principles of Inheritance and Variation, genetics, the inheritance of traits, mutation, gene flow, and various laws in genetics. NCERT exemplar solution will also help you to understand the Mendelian laws of inheritance and Punnett square formation.

NCERT Exemplar Class 12 Biology Solutions Chapter 5- Principles of Inheritance and Variation have a total of 53 questions that are divided into 4 sections touching all the topics based on Chapter 5- Principles of Inheritance and Variation. The questions are of various kinds which will help you get a complete revision with the help of short and long type questions, objective type questions, and MCQs kind of questions 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 5- Principles of Inheritance and Variation

  1. Genetics is a study of the principles and practices of genetics and diversity.
  2. Gregor Johan Mendel is known as the “father of genetics”.
  3. Inheritance is the process of transferring characters from parents to offspring. This is the basis of genetics. Variation is the degree to which the offspring differ from their parents.
  4.  Variations can range from morphology, physiology, cytology, and behavioural characteristics of people of the same species.
  5. Mendel’s Law of Inheritance: Mendel conducted hybrid experiments on garden peas for seven years, and proposed this law.

Pea Plant Selection: The reasons for adopting garden peas (Pisum sativum) for Mendel’s experiments were: 

  • Peas have many different opposite characters. 
  • The pea plant has a short shelf life.
  • The flower reflects self-pollination.
  • Pea blossoms are easy to artificially pollinate. 

Principle or Law of Inheritance

Based on observations of a monohybrid cross, Mendel proposed two law of inheritance-

  • Law of dominance– 
  • Characters controlled by discrete units known as factors.
    b.Factors must occur in pairs.
    Law of Segregation- alleles never blend. Also, both characters are restored during gametes formation in the F2 generation. Traits segregate during gamete formation from each other alongside passes to different gametes.
  • Incomplete dominance: It is the phenomenon in which neither of the two pairs is predominant because the expression in the hybrid is a finer mixture or intermediate between the expressions of the two pairs.


  • When there is a lack of dominance-recessive relationship within two alleles, at that time both will express themselves in the organism.
  • Multiple Alleles

They are multiple forms of the Mendelian factor, or gene, that occur at the same genetic locus distributed across different organisms in the gene pool, carrying only two alleles and a gamete with only one allele. 

  • Chromosomal Theory of Inheritance

  Both Chromosomes, as well as genes, occur in pairs. The two alleles of a gene pair are located on the same locus on homologous chromosomes.

  • Sex Determination-

The sexual determination system is biological. Science is the system that determines the development of sexual characteristics in an organism.

  • A mutation is a phenomenon that leads to alteration of the DNA sequence and consequently changes the genotype and phenotype of an organism. Mutations resulting from single base-pair DNA modification are called point mutations, e.g. Sickle-cell anaemia.
  • Pedigree Analysis
  • Family Analysis of characteristics of several generations of a single-family.
  • Genetic Disorders Hereditary disorders are health problems caused by one or more abnormalities in the genome. It can be due to mutations caused by a single gene (single gene) or multiple genes (multigene) or chromosomal abnormalities.

They are transmitted leading to sterility. It is always dominant.

They are categorized into Mendelian and chromosomal disorders.

  1. Mendelian disorder: characterized by single gene alteration and can be transmitted for examples are Color blindness Phenylketonuria.
  2. Chromosomal disorders: due to absence or excess of single or more chromosomes. They are either recessive or dominant.  Examples are Down syndrome, Turner’s syndrome.

Discussion of Exercises of NCERT Exemplar Class 12 Biology Solutions Chapter 5- Principles of Inheritance and Variation

  1. The first section of NCERT Exemplar Class 12  Biology Solutions Chapter 5 has 18 questions which are MCQs that are based on different concepts of genes and recombination of genes, genetic diseases, karyotype conditions, sex determination, test and back cross monohybrid, and dihybrid cross.
  2. The third section has 15 questions which are very short answer type questions that will help you to understand different laws of inheritance, cross-pollination and pedigree charts.
  3. The fourth section has 15 questions which are short answer types that will ask you about the nature of alleles involved in a given monohybrid cross.
  4. The fifth section has 5 questions which are long answer type questions that are based on numerical related to monohybrid cross, colour blindness, homogametic and homogametic situations.
  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 5- Principles of Inheritance and Variation 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.