{"id":35752,"date":"2022-05-24T17:27:43","date_gmt":"2022-05-24T11:57:43","guid":{"rendered":"https:\/\/www.cbselabs.com\/?p=35752"},"modified":"2022-05-24T17:46:35","modified_gmt":"2022-05-24T12:16:35","slug":"heredity-and-evolution-cbse-notes-for-class-10-science","status":"publish","type":"post","link":"https:\/\/www.cbselabs.com\/heredity-and-evolution-cbse-notes-for-class-10-science\/","title":{"rendered":"Heredity and Evolution Class 10 Notes Science Chapter 9"},"content":{"rendered":"

CBSE Notes<\/a>CBSE Notes Science<\/a>NCERT Solutions Science<\/a><\/p>\n

CBSE Class 10 Science Notes Chapter 9 Heredity and Evolution Pdf free download is part of Class 10 Science Notes<\/a> for Quick Revision. Here we have given NCERT Class 10 Science Notes Chapter 9 Heredity and Evolution. https:\/\/www.cbselabs.com\/heredity-and-evolution-cbse-notes-for-class-10-science\/<\/p>\n

According to new CBSE Exam Pattern,\u00a0MCQ Questions for Class 10 Science pdf<\/a>\u00a0Carries 20 Marks.<\/p>\n

CBSE Class 10 Science Notes Chapter 9 Heredity and Evolution<\/h2>\n

Heredity And Evolution Class 10 Notes Chapter 9\u00a0<\/strong><\/p>\n

Heredity and Inherited Traits:<\/strong> Mendel\u2019s Experiment; Sex determination.
\nHeredity refers to the transmission of characters from parents to offsprings. An inherited trait is a particular genetically determined feature that distinguishes a person from the others for example; attached or free ear lobes in human beings.<\/p>\n

Rules for the inheritance of traits:<\/strong>
\nMendel\u2019s contribution:<\/strong> The rules for inheritance of traits in human beings are related to the fact that both mother and father contribute an equal amount of genetic material i.e. DNA to their offspring. So an offspring will get two versions of that trait from the two parents. Mendel worked out rules for inheritance of these traits. Gregor Johann Mendel regarded as the \u2018Father of Genetics\u2019 performed his experiments with garden peas (Pisum sativum) in the garden behind his monastery. He observed a number of contrasting characters in garden peas and observed their inheritance.<\/p>\n

Some important terms
\n1. Chromosomes are long thread-like structures present in the nucleus of a cell which contain hereditary information of the cell in the form of genes.<\/p>\n

2. DNA is a chemical in the chromosome which carries the traits in a coded form.<\/p>\n

3. Gene is the part of a chromosome which controls a specific biological function.<\/p>\n

4. Contrasting characters: A pair of visible charactes such as tall and dwarf, white and violet flowers, round and wrinkled seeds, green and yellow seeds etc.<\/p>\n

5. Dominant trait: The character which expresses itself in a (Ft) generation is dominant trait. Example : Tallness is a dominant character in pea plant.<\/p>\n

6. Recessive trait: The character which does not express itself but is present in a generation is recessive trait. Ex. dwarfism in the pea plant.<\/p>\n

7. Homozygous: A condition in which both the genes of same type are present for example; an organism has both the genes for tallness it is expressed as TT and genes for dwarfness are written as tt.<\/p>\n

8. Heterozygous: A condition in which both the genes are of different types for example; an organism has genes Tt it means it has a gene for tallness and the other for dwarfness only tall character is expressed.<\/p>\n

9. Genotype: It is genetic make up of an individual for example; A pure tall plant is expressed as TT and hybrid tall as Tt.<\/p>\n

10. Phenotype: It is external appearance of the organism for example; a plant having Tt composition will appear tall although it has gene for dwarfness.<\/p>\n

11. Homologous pair of characters are those in which one member is contributed by the father and the other member by the mother and both have genes for the same character at the same position.<\/p>\n

Heredity And Evolution Class 10 Chapter 9\u00a0<\/strong><\/p>\n

Mendel\u2019s Experiment:<\/strong> Mendel started his experiment on the pea plants. He conducted first monohybrid and then dihybrid crosses.<\/p>\n

Monohybrid Cross:<\/strong> The cross in which Mendel showed inheritance of dominant and recessive characters is monohybrid cross. To observe inheritance of single pair of contrasting characters
\n\"Heredity
\nhe took pure tall (genotype TT) and pure dwarf (genotype tt) pea plants and cross pollinated them to obtain first generation or first filial generation. In this figuration (F1 generation) he obtained only tall plants. This meant that only one of the parental traits was seen, not the mixture of the two. The plants of F generation or progeny are then self pollinated to obtain F2 generation or progeny. Now all plants were not tall. He obtained 75% tall plants and 25% dwarf plants i.e. the phenotypic ratio was 3:1. This indicates that in the F, generation both tall and dwarf traits were inherited but tallness expressed it self. Tallness is a dominant trait and dwarfness is a recessive trait. F2 generation has a genotypic ratio of 1 : 2 : 1 of three types of plants represented by TT, Tt and tt as shown in the cross.<\/p>\n

Conclusion:<\/strong> Phenotypic ratio\u2014Tall : Dwarf 3 : 1
\nGenotype ratio\u2014Pure Tall : Hybrid Tall : Pure Dwarf 1 : 2 : 1<\/p>\n

Class 10 Heredity And Evolution Notes Chapter 9\u00a0<\/strong><\/p>\n

Law of Dominance:<\/strong> When parents having pure contrasting characters are crossed then only one character expresses itself in the Ft generation. This character is the dominant character and the character\/factor which cannot express itself is called the recessive character.<\/p>\n

Dihybrid Cross:<\/strong> Mendel also carried out experiments to observe inheritance of two pairs of contrasting characters, which is called dihybrid cross. He cross breed pea plants bearing round green seed with plants bearing wrinkled and yellow seeds. In the Fx generation he obtained all round and yellow seeds it means round and yellow traits of seeds are dominant features while wrinkled and green are recessive. He self-pollinated the plants of F: generation to obtain F2 generation, he obtained four different types of seeds round yellow, round green, wrinkled yellow and wrinkled green in the ratio of 9 : 3 : 3 : 1. He concluded that traits are independently inherited<\/p>\n

Conclusion<\/strong><\/p>\n