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Principle of Inheritance and Variation Part 2 (in Hindi)
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All important topics releated to this chapter.

Shivam Sharma
Learning and teaching Biology, pursuing medical studies at TU.

Unacademy user
Good Morning sir. sir will u plz make a video on word limits or can say how we hv to follow it as in agaar 5-10 words jyada ho gaya tho chalega ki nahi sort of. if possible show us any example answer writin sheet as a demo or will get idea about it cus i hvnt join classes or i dnt knw any1who cn tell me abt answer writing.plz plz do make it... THANK YOU SIR.
Mohit Saxena
2 years ago
You can watch tina dabi answer writing video it's really helpful on you YouTube of 6 min !!!!!
Sneha Bharati
2 years ago
thank u
Sir mujhe test cross smjha nhi aaya.. Plz aap kya test cross ko or aache se smjha skte hai.. plz sir

  2. MONOHYBRID CROSS Dwarf p Phenotype Tal Genotype TT Homozygous Dominant Homozygous Recessive Tt All Tall F1 Self pollinated F2 Tall is dominant Heterozygous to Dwarf Gamets Tt tall tall Tt Tall dwarf Phenotypic ratio 3:1 Genotypic ratio:12:1

  3. .Production of gametes & formation of zygotes- Punnett Square Developed by- British scientist Reginald C. Punnett Graphical representation- calculate probability of possible genotypes in genetic cross Gametes- on two sides, top row & left columns TT dwarf tall Self-pollination-50% phenotypically genotype Gametes TT* . F2-3/4th tall & 1/4th Dwarf- Fi generation TtTt Tt t Tt . 1/4 : : ratio of TT: Tt: tt- tall selfing tall Gametes T , t T, t T TTTt F2 generation

  4. Test cross: The cross between hybrid and its homozygous recessive parent I called test cross. It is used to identify the genotype of the hybrid. Dominant phenotype (allele distribution unknown) if PP if Pp P) p Homozygous recessive All offspring purple; (white) tfore unknown Homozygous recessive Half of offspring (white)white; therefore flower was homozygous unknown flower was heterozygous Alternative 1 Alternative 2

  5. MENDELIAN LAWS OF HEREDITY. .Rules were proposed- Principles or Laws of Inheritance: First Law or Law of Dominance & Second law or Law of Segregation . LAW OF DOMINANCE 1. Characters are controlled by discrete units called Factors 2. Factors occurs in pair 3. In a dissimilar pair of factors one member of the pair dominates (dominant) the other (recessive) Used to explain the expression of only one of the parental characters in monohybrid cross (F1) & expression of both in F2. Also explains proportion 3:1 in F2

  6. LAW OF SEGREGATION It states that, 'when a pair of factors for a character brought together in a hybrid, they segregate (separate) during the formation of gametes. .Alleles do not blend & both characters recovered in F2 & one in F1 Factors which is present in parent segregate & gametes receives only one of two factors Homozygous parent- one kind gamete Heterozygous parent- two kind gamete each one have one allele with equal proportion

  7. INCOMPLETE DOMINANCE: Correns discovered Incomplete dominance in Merabili:s jalapa. It is also called partial dominance, semi dominance. . The inheritance in which allele for a specific character is not completely dominant over other allele is called Incomplete dominance Snapdragon or Antirrhinum sp.- Cross between true breed red flower (RR) & white flower (rr), F1 generation- Pink (Rr) & after self pollination in F2 generation- 1 (RR) Red: 2 (Rr) Pink: 1 (rr) white Genotype ratio same as Mendelian cross & Phenotype ratio different than Mendelian cross

  8. Incomplete dominance: Ex snapdragon. (Dog flower plant)

  9. P Generation Red White Gametes F1 Generation Pink Rr Gametes 2 Eggs 2 Spermm Red F2 Generation Pink Rr Pink rR White

  10. Red X White Parent: Genotype Gametes F1 g eneration Pink (Hybrid) RW Self pollination F2 generation GametesR RW Pink wW Pink white Red RW The phenotypic ratio is The genotypic ratio is 1:2:1

  11. A and iB are co-dominant and dominant over i. Blood Group Genotype IAIA or IA i A- Group B-Group AB-Group O-Group IAIB

  12. ABO blood grouping- multiple allele . Three alleles govern same character . Multiple allele is found when population studies are made . Single gene product may produce more than one effect Eg.- Starch Synthesis in Pea seeds- controlled by a gene having two allele B & b Starch synthesis effective if homozygote BB & produce large starch grains Homozygote bb-lesser efficiency in starch synthesis & seeds are wrinkled Heterozygote Bb-round seeds, intermediate size .