<h3 id="successgenetics-and-evolutionsuccess"><Success>Genetics and evolution</Success></h3> <h4 id="successpriciples-of-inheritance-and-variables-1success"><Success>Priciples of inheritance and variables-1</Success></h4> </div> <div style='float: left; width:100%;font-size:30px;text-align:left;'> </div>

<h3 id="successgenetics-and-evolutionsuccess-1"><Success>Genetics and evolution</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ul> <li>Principles of Inheritance and Variation - I</li> </ul> <ul> <li>Genetics - study of heredity and variation</li> <li>The term ‘genetics’ was coined by - William Bateson in 1906</li> <li>Gregor Johann Mendel - Father of Genetics</li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-2.jpg"> <img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-2a.jpg"></p> </div>

<h3 id="successgenetics-and-evolutionsuccess-2"><Success>Genetics and evolution</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ul> <li>Heredity - Tendency of progenies to resemble with their parents</li> <li>Variation - Tendency of progenies to differ from their parents</li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-3.jpg"></p> </div>

<h3 id="successlife-sketch-of-mendelsuccess"><Success>Life sketch of Mendel</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ul> <li>Born in 1822 in a peasant family in Moravia, in Austria</li> <li>He became a monk in the Augustinian monastery at Brunn in Austria in 1843</li> <li>Later ordained as a priest in 1847</li> <li>Later, he became a teacher</li> <li>He published his findings in 1866 in the Annual Proceeding of Natural History Society of Brunn</li> <li>His laws form the basis of science for genetics. So, he is known as the Father of Genetics</li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-4.jpg"> <img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-4a.jpg"></p> </div>

<h3 id="successlife-sketch-of-mendelsuccess-1"><Success>Life sketch of Mendel</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ul> <li>He attended courses in Physics, Maths and Science in Vienna University</li> <li>He conducted hybridization experiments on pea plants at his monastery gardens from 1856 to 1865</li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-5.jpg"></p> </div>

<h3 id="successwhy-his-work-remained-hiddensuccess"><Success>Why his work remained hidden?</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ul> <li>His work was ahead of his time</li> <li>His work was published in a journal that had limited circulation</li> <li>He himself was not sure of his findings</li> <li>His mathematical approach in working out biological problems was strange</li> <li>All the biologists were busy with Darwin’s Theory of Evolution</li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-6.jpg"> <img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-6a.jpg"></p> </div>

<h4 id="successrediscovery-of-mendels-findingssuccess"><Success>Rediscovery of Mendel’s findings</Success></h4> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ul> <li>Mendel’s findings were re-discovered by the scientists</li> <li>Hugo de Vries of Netherland</li> <li>Karl Correns of Germany</li> <li>Erich von Tshermak of Austria in 1900</li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-7.jpg"> <img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-7a.jpg"></p> </div>

<h4 id="successmendels-experiment-plant-garden-pea---pisum-sativum-success"><Success>Mendel’s experiment plant (Garden Pea - Pisum sativum )</Success></h4> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ul> <li> <p>Why Mendel selected pea plant as his experimental material ?</p> </li> <li> <p>it is a herbaceous plant with very short lifecycle</p> </li> <li> <p>Availability of large number of varieties</p> </li> <li> <p>Availability of large number of seeds</p> </li> <li> <p>Presence of large number of contrasting characters</p> </li> <li> <p>Bisexual flowers with self pollination</p> </li> <li> <p>Papillionaceous corolla</p> </li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-8.jpg"> <img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-8a.jpg"></p> </div>

<h3 id="successsome-important-termssuccess"><Success>Some important terms</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ul> <li> <p>Gene - the unit of heredity or unit of inheritance of characters or unit of transmission of characters from parents to offsprings,which is a part of DNA present in the nucleus of a cell</p> </li> <li> <p>A character is controlled by a pair of characters</p> </li> <li> <p>Alleles or allelomorphs -alternative forms of the same gene found in the same locus of homologous chromosome</p> </li> <li> <p>Example -T and t are alleles of the same gene that controls the character height</p> </li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-10.jpg"> <img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-10a.jpg"></p> </div>

<h3 id="successsome-important-termssuccess-1"><Success>Some important terms</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ul> <li>Phenotype - refers to the external characters of an organism for a particular trait. It controlled by genes and the external environment</li> <li>Genotype - refers to the genetic make up or genetic constitution of an individual for a trait</li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-11.jpg"></p> </div>

<h3 id="successhomozygoussuccess"><Success>Homozygous</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <p>Homozygous- an individual bears two similar alleles at a given locus</p> <ul> <li>Example- RR for red phenotype of the flower</li> <li>Heterozygous- an individual bears two dissimilar alleles for a character seen at a given locus</li> <li>Example- Rr for red flower colour</li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-12.jpg"></p> </div>

<h3 id="successhomozygoussuccess-1"><Success>Homozygous</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ul> <li>Pure line or true breeding - an individual that produces same type of progenies in all the generations based on a particular phenotype</li> <li>They are always homozygous</li> <li>Continuous inbreeding or self pollination results in the production of a pure line individual.</li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-13.jpg"></p> </div>

<h3 id="successsymbolisation-of-characterssuccess"><Success>Symbolisation of characters</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ul> <li>First letter of the dominant character is taken</li> <li>First letter is written as capital letter for dominant character</li> <li>First letter is written as small letter for recessive character</li> <li>TT-for tall</li> <li>tt-for dwarf</li> <li>B - for dwarf</li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-14.jpg"></p> </div>

<h3 id="successanother-method-of-representationsuccess"><Success>Another method of representation</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ul> <li>Consider the first letter of the recessive . character</li> <li>Write the first letter capital for dominant character</li> <li>Write the first letter as small letter for recessive character</li> <li>Example - DD -Tall</li> <li>dd - Dwarf</li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-15.jpg"></p> </div>

<h3 id="successmonohybrid-crosssuccess"><Success>Monohybrid cross</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ol> <li>Length of the stem - Tall $\quad$ Dwarf</li> <li>Colour of the flower - Purple $\quad$ White</li> <li>Position of the flower - Axial $\quad$ Terminal</li> <li>Colour of the pod - Green $\quad$ Yellow</li> <li>Shape of the pod - Inflated $\quad$ Constriction</li> <li>Colour of the seed - Yellow$\quad$ Green</li> <li>Shape of the seed - Round $\quad$ wrinkled</li> </ol> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-17.jpg"></p> </div>

<<h3 id="successmonohybrid-crosssuccess-1"><Success>Monohybrid cross</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ul> <li>Cross between two parents differing in one pair of characters</li> <li>Example -Tall X Dwarf</li> <li>Purple X White</li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-18.jpg"></p> </div>

<h3 id="success-mendels-experimentsuccess"><Success> Mendel’s Experiment</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ol> <li>Selection of pure breeding parents</li> </ol> <ul> <li>Continuous self pollination</li> <li>They are homozygous</li> <li>They will pass the character to the progenies as such</li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-19.jpg"></p> </div>

<h3 id="successhybridisation-of-parentssuccess"><Success>Hybridisation of parents</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ul> <li>Tall plant as male parent</li> <li>Dwarf plant as female parent</li> <li>Bagging of flowers of both the plants</li> <li>Collected pollen grains from tall plants</li> <li>Dusted on the stigma of dwarf plant</li> <li>Bagging of cross pollinated flowers</li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-20.jpg"></p> </div>

<h3 id="successhybridisation-of-parentssuccess-1"><Success>Hybridisation of parents</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ul> <li>Collection and sowing of seeds</li> <li>Tall hybrid plants obtained</li> <li>F1 generation (first filial generation)</li> <li>Filial refers to offspring</li> <li>The symbol ‘F1’ - coined by Bateson and Saunders in 1902</li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-21.jpg"></p> </div>

<h3 id="successself-pollination-in-f1-hybridssuccess"><Success>Self Pollination in F1 Hybrids</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ul> <li>Bagging of flowers of F1 plants</li> <li>It prevents contamination with foreign pollens</li> <li>Collected and sown seeds</li> <li>F2 generation is obtained</li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-22.jpg"></p> </div>

<h3 id="successobservation-in-f2success"><Success>Observation in F2</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ul> <li>Three tall and one dwarf progenies</li> <li>Selfing of F2 progenies to produce F3 generation</li> <li>1/3 tall - produced tall only</li> <li>2/3 tall 3:1 - produced both tall and dwarf in the ratio</li> <li>1/4 (dwarf) - produced dwarf only</li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-23.jpg"></p> </div>

<h3 id="successphenotypic-and-genotypic-ratiosuccess"><Success>Phenotypic and Genotypic ratio</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ul> <li> <p>Phenotypic ratio - 3:1</p> </li> <li> <p>Genotypic ratio - 1:2:1</p> </li> </ul> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-24.jpg"></p> </div>

<h3 id="successreview-questionssuccess"><Success>Review questions</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <p><strong>Question 1.</strong> How can we convert a bisexual flower into a female flower?</p> <p><strong>Answer</strong> we can convert a bisexual flower in to female flower by removing the anthers before dehiscence.(Emasculation)</p> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-25.jpg"></p> </div>

<h4 id="successidentify-the-following-as-dominant-and-recessive-characterssuccess"><Success>Identify the following as dominant and recessive characters</Success></h4> <div style='float: left; width:100%; text-align:left; font-size:30px'> <ul> <li>Axial flower, wrinkled seed</li> <li>red flower, constricted pod</li> <li>Yellow seed, Green pod</li> </ul> <p>Answer- Axial flower, red flower, Yellow seed Green pod are dominant Wrinkled seed, constricted pod, are recessive</p> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-26.jpg"></p> </div>

<h3 id="successthink-it-oversuccess"><Success>Think it over!</Success></h3> <div style='float: left; width:100%; text-align:left; font-size:30px'> <p><strong>Question.</strong> Is there any need for emasculation in pea plant that is considered as male parent? If not why?</p> </div> <div style='float: right; width:0%;'> <p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-05-chapter-01-genetics-evolution-principles-of-inheritance-variation-l-1_7-eqd8jnbu2_c-27.jpg"></p> </div>

<h3 id="successthank-yousuccess"><Success>Thank you</Success></h3>