NCERT Solutions Class 12 Biology Chapter 5

NCERT Solutions Class 12 Biology Chapter 5

The study of life is known as biology. Biologists investigate the structure, function, growth, origin, evolution, and distribution of living creatures. Biologists have used advances in biology to help develop better  medicines and treatments, understand how climate change affects plants and animals, produce enough food for a growing human population, and predict how eating new foods or sticking to an exercise regimen will affect our bodies.

NCERT Class 12 Biology Chapter 5:Principles of Inheritance and Variations.

The Fundamentals of Iinheritance and Vvariations provides an overview of Genetics, a field of Biology. Understanding the genetic and the structural basis of genotype and phenotype material became the focus of study. and  It describes   how genes get handed down from parents to children, and why do siblings look alike? This chapter answers all of these  questions.  This chapter also covers Mendel’s pea plant studies, the inheritance of one gene, the inheritance of two genes, sex determination, mutation, and genetic diseases.

Class 12 students are advised to go through NCERT Solutions for board examination preparation.  Extramarks has  with Chapter 5 Biology Class 12 NCERT Solutions. Prepared after thorough research, these Biology Class 12 Chapter 5 NCERT Solutions meet all the requirements of the students.

Students must go through NCERT books first.It’s not necessary to opt for coaching classes. When you study from NCERT Solutions for Class 12 Science Biology Chapter 5 diligently, you will be able to understand every concept and answer any question easily. This encourages the students to master the topic and increases their confidence in achieving a higher grade. 

Apart from Chapter 5 Class 12 Biology NCERT Solutions, students can use the Extramarks website to access  other study materials such as . NCERT books, CBSE revision notes, CBSE sample papers, CBSE  past years’ question papers, and so on. 

Key Topics Covered in NCERT Solutions Class 12 Biology Chapter 5

To make it convenient for the students, Extramarks has listed  key topics that are covered in NCERT Solutions Class 12 Biology Chapter 5:

Let us look at Extramarks’ in-depth information on each subtopic in NCERT Solutions Class 12 Biology Chapter 5- Principles of Inheritance and Variations.

What is Hereditary?

NCERT Solutions Class 12 Biology Chapter 5 explains that Heredity is how genes are passed down from generation to generation through sexual reproduction. Various genes and inheritable characteristics are handed down to ensure that the kids produced are better suited to the changing environment. The traits are encoded in the form of genes on the chromosomes. Gregor Johann Mendel is known as “the father of genetics.”

Mendel’s Law of Inheritance 

NCERT Solutions Class 12 Biology Chapter 5 says that after researching pea plants, Gregor Mendel established the fundamental inheritance laws. First, he offered three inheritance rules, which we are now studying. Then, he picked 14 true-breeding pea plant kinds with seven opposing features of specific attributes and conducted his experiment on them.

Mendel’s Laws

NCERT Solutions Class 12 Biology Chapter 5 explains that Mendel postulated the following three laws:

• Law of Dominance- This law states that the unit known as the factor is in charge of all qualities or characters. Alleles refer to the fact that these factors are found in pairs. If the alleles are located in the same pair, they are termed homozygous, and they can be dominant or recessive. If the alleles are found in separate pairs, they are called heterozygous, and they will always be dominant.
• Law of Segregation of Genes- The law of segregation is based on alleles that do not blend, and both traits are recovered as such in the second filial generation, even though one of them was not observed in the first. The segregation of factors or alleles happens such that each gamete receives just one of the two factors.
• Law of Independent Assortment asserts that while transmitted from one generation to the next, pairings of qualities in the parental generation sort independently of one another. A dihybrid cross is used to demonstrate it.

Inheritance of one Gene:

A monohybrid cross can be used to explain the inheritance of one gene using Mendel’s law. The tall and dwarf plants are crossed in this experiment, resulting in all tall hybrid plants in the F1 (First Filial or First) generation. The progenies are then self-pollinated, resulting in forming an F2 era with three tall plants and one dwarf plant. As a result, the proportion will be 3:1.

Incomplete Dominance:

Incomplete dominance is a kind of inheritance in which one allele for a particular characteristic is not dominant over the other allele, i.e., in heterozygous organisms, neither allele is dominant over the other. As a result, a mixed phenotype emerges. Mosaic or partial dominance are different terms for incomplete dominance. New phenotypic characteristics are fully manifested here.

Multiple Allelism or Codominance:

Extramarks NCERT Solutions Class 12 Biology Chapter 5 states that Multiple Allelism is a situation in which three or more alternate kinds of alleles exist for the same gene on the same chromosome, and the alleles are known as multiple alleles.

Multiple allelism, for example, is better understood in humans because of the ABO blood type system. The ABO blood group is inherited through the gene I (isohemagglutinin), which exists in three allelic manifestations in humans: IA, IB, and i. Any two of these alleles can be found in a single person. Blood type A is controlled by gene IA, which codes for glycoprotein A, while blood group B is controlled by gene IB, which codes for glycoprotein B.

Because the gene I does not create any glycoprotein, a person with these two alleles in a homozygous form will have O group blood. The genes IA and IB are dominant over I, but alleles IA and IB are equally prevalent and generate both glycoproteins A and B at the same time, giving rise to the blood type AB. These alleles are referred to as codominant alleles.

Inheritance of two Genes:

Two features of the same trait are required to inherit two genes. A dihybrid cross can be used to demonstrate this. To describe the inheritance of two genes, Mendel picked two features that affect the seed’s colour and form. R denotes the round form of the seed, and r represents the wrinkled shape of the seed. Y represents the dominant yellow colour seed colour, y represents a recessive green colour, and y represents a recessive green colour. The parents’ genotypes are then indicated as RRYY and rryy. After fertilisation, the gametes RY and ry will combine to form the F1 hybrid RrYy. The Law of Independent Assortment may also be studied using the dihybrid cross.

Chromosomal Theory of Inheritance

Walter Sutton proposed the chromosomal hypothesis of heredity in 1902. This hypothesis also explains the linear shape of chromosomes with genes in specific locations called loci, which Boveri investigated separately. The Boveri-Sutton chromosome theory is another name for this notion. According to this theory:

• First, genes are located on chromosomes at specific sites.
• Second, the homologous chromosomes split during meiosis.
• Third, the number of chromosomes becomes diploid after conception.
• Finally, chromosomes segregate and assort on their own.

Sex Determination

NCERT Solutions Class 12 Biology Chapter 5 explains the procedure of determining a child’s gender is known as sex determination. Sex chromosomes are responsible for selecting a child’s gender. In humans, females have XX chromosomes, whereas males have one X and one Y type. As a result, each egg (female gamete) will contain an identical X-chromosome, whereas (male gametes) will have one X-chromosome and one Y-chromosome. So which sperm unites with the egg is a question of luck (X or Y). In addition, females are homogametic (chromosomes of the same kind), whereas males are heterogametic (chromosomes of different types) (other types of chromosomes).

In insects, the XO type of sex determination mechanism is used. The X chromosomes are present in the females, but the males may contain one or no X chromosomes. Males are homogametic (chromosomes of the same kind), whereas females are heterogametic (chromosomes of different sorts) (different types of chromosomes).

Mutation

The concept of Mutations has been explained in the following section of NCERT Solutions Class 12 Biology Chapter 5.

Mutation is defined as a change in the genetic material. . Changes in DNA may be heritable and handed down to future generations, impacting both an individual’s genotype and phenotype. Examples are frameshift mutations, insertions, deletions, duplications, substitutions, and other mutations. Mutations might be damaging or have no impact.

• Frameshift mutations occur when added or deleted DNA bases, causes alterations in the reading frame.
• Insertions are the addition of new DNA bases.
• Deletions are the removal of DNA bases.
• Duplication occurs when a portion of DNA is duplicated more than once.

As a result of these mutations, the DNA sequence will alter, leading to the creation of the incorrect protein.

Genetic Disorders

Pedigree Analysis

A pedigree chart depicts the incidence and emergence of specific phenotypes of a particular gene and organism. Consequently, the family information is presented in an easily legible chart.

NCERT Solutions Class 12 Biology Chapter 5 describes the two types of genetic disorders :

Mendelian Disorders- Mendelian diseases are caused by a single gene mutation or change. Haemophilia, Sickle-cell anaemia, Cystic fibrosis, Colour blindness, Thalassemia, Phenylketonuria, and other disorders are among the most frequent. Mendelian diseases are classified as dominant or recessive. The attribute has also been connected to conditions caused by sex chromosomes, such as haemophilia and colour blindness.

Chromosomal Disorders- Chromosomal disorders are caused by adding or removing one or more chromosomes or by their aberrant organisation. The faulty segregation of chromatids during the cell division cycle results in aneuploidy, characterised by the addition or deletion of chromosomes. For example, an additional copy of chromosome 21 is found in Down’s syndrome patients. The omission of one X chromosome characterises Turner’s syndrome in human females. The other circumstance is polyploidy, which occurs when the cytokinesis process is absent after the telophase stage of cell division, resulting in an increase in a complete set of chromosomes in an organism, most commonly seen in plants.

NCERT Solutions Class 12 Biology Chapter 5 Exercise and Solutions

Extramarks  provides high-quality study resources that are aligned with CBSE examination guidelines. Extramarks’ subject matter experts have produced study materials for students to  get an edge over their peers with superior knowledge and understanding of the subject.

Students can select resources as per their need and requirement.. Click on the  links below to check the  NCERT Solutions Class 12 Biology Chapter 5:

Class 12 Biology Chapter 5: Very Short Answer Type Questions

Class 12 Biology Chapter 5: Short Answer Type Questio

Class 12 Biology Chapter 5: Long Answer Type Questions

Students can access NCERT Solutions Class 12 Biology Chapter 5 and other chapters by clicking here. In addition, students can also explore NCERT Solutions for other classes given below.

• NCERT Solutions Class 1
• NCERT Solutions Class 2
• NCERT Solutions Class 3
• NCERT Solutions Class 4
• NCERT Solutions Class 5
• NCERT Solutions Class 6
• NCERT Solutions Class 7
• NCERT Solutions Class 8
• NCERT Solutions Class 9
• NCERT Solutions Class 10
• NCERT Solutions Class 11
• NCERT Solutions Class 12

By getting access to NCERT Solutions Class 12 Biology Chapter 5, students can easily understand all the concepts related  to Inheritance and Variation.

Key Features of NCERT Solutions Class 12 Biology Chapter 5 

NCERT Solutions are a golden feature of Extramarks. These Solutions provide students with a better understanding of the chapter and help them achieve their goals. NCERT Solutions are often recommended to students, and hence, there are plenty available on google. But why choose Extramarks? Here’s why:

• These solutions have been developed following a straightforward language approach to make it easy for students to comprehend the concepts.
• Extramarks NCERT Solutions have been prepared exclusively by subject experts after careful research of the chapters.
• These Solutions have been prepared to keep in mind the NCERT guidelines.