biology-class-12-unit-05-chapter-04-genetics-evolution-principles-of-inheritance-variation-l-4-7-cks7v9jspfe

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritance Variation L-4 </Success>
### <primary style="font-size:24px"> Incomplete dominance </primary>
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* Intermediate dominance
* Blending inheritance
* Mosaic dominance
* Partial dominance
* When a dominant parent is crossed with a recessive parent, the F1 produces an intermediate phenotype between the two parents

- **Examples**

* Flower colour in _Mirabilis Jalapa_
 * Flower colour in _Antirrhinum Majus_
 * Feather colour in _Andalusian Fowl_

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![image](/subject-images/iitpal/image/biology-class-12-unit-05-chapter-04-genetics-evolution-principles-of-inheritance-variation-l-4_7-cks7v9jspfe-04.jpg)
![image](/subject-images/iitpal/image/biology-class-12-unit-05-chapter-04-genetics-evolution-principles-of-inheritance-variation-l-4_7-cks7v9jspfe-8.jpg)

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<footer style = "font-size: 18px">Dihybrid cross $\rightarrow$ Dihybrid cross $\rightarrow$ <span style = "color:blue"> Incomplete dominance </span> $\rightarrow$ Incomplete dominance $\rightarrow$ Flower colour in _Mirabilis Jalapa_ </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritance Variation L-4 </Success>
### <primary style="font-size:24px"> Incomplete dominance </primary>
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* **_Mirabilis Jalapa_**, the four o'clock flower, is the most commonly grown ornamental species of _Mirabilis_ plant
* It is available in a range of colours
* _Mirabilis_ in Latin means wonderful and Jalapa is a common place name in Central and North America

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<footer style = "font-size: 18px">Dihybrid cross $\rightarrow$ Incomplete dominance $\rightarrow$ <span style = "color:blue"> Incomplete dominance </span> $\rightarrow$ Flower colour in _Mirabilis Jalapa_ $\rightarrow$ Incomplete dominance </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritance Variation L-4 </Success>
### <primary style="font-size:24px"> Flower colour in _Mirabilis Jalapa_ </primary>
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* Pure breeding red flowered four'o clock plant is crossed with pure breeding white flowered plant.

* In the F<sub>1</sub> all the progenies are pink in phenotype.

* F<sub>1</sub> on selfing to produce F<sub>2</sub> generation, It was found that progenies appear in an 1:2:1 ratio regarding the phenotype red,pink,white.

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![image](/subject-images/iitpal/image/biology-class-12-unit-05-chapter-04-genetics-evolution-principles-of-inheritance-variation-l-4_7-cks7v9jspfe-10.jpg)

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<footer style = "font-size: 18px">Incomplete dominance $\rightarrow$ Incomplete dominance $\rightarrow$ <span style = "color:blue"> Flower colour in _Mirabilis Jalapa_ </span> $\rightarrow$ Incomplete dominance $\rightarrow$ Incomplete dominance </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritance Variation L-4 </Success>
### <primary style="font-size:24px"> Incomplete dominance in _Mirablis jalapa_ </primary>
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* R gene for red is incompletely dominant over r gene for white

* Both R and r alleles contribute almost equally in the production of the phenotype pink

* Genes for red and white do not mix in the F<sub>1</sub> hybrids as both red and white characters appear in the F<sub>2</sub> progenies
* There is no specific gene for pink flower colour
* There is no quantitative effect of genes
* Genotypic and phenotypic ratio remains the same (1:2:1)

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![image](/subject-images/iitpal/image/biology-class-12-unit-05-chapter-04-genetics-evolution-principles-of-inheritance-variation-l-4_7-cks7v9jspfe-14.jpg)

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<footer style = "font-size: 18px">Incomplete dominance $\rightarrow$ Incomplete dominance in _Mirablis jalapa_ $\rightarrow$ <span style = "color:blue"> Incomplete dominance in _Mirablis jalapa_ </span> $\rightarrow$ Flower colour in snapdragon $\rightarrow$ Flower colour in snapdragon </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritance Variation L-4 </Success>
### <primary style="font-size:24px"> Flower colour in snapdragon </primary>
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* In _Antirrhinum majus_ red flowered plant crossed with white flowered one produced pink flowered progenies
* In the F<sub>2</sub> - 1 (red): 2 (pink) :1 (white) plants are produced
* Modified mendelian ratio

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![image](/subject-images/iitpal/image/biology-class-12-unit-05-chapter-04-genetics-evolution-principles-of-inheritance-variation-l-4_7-cks7v9jspfe-17.jpg)

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<footer style = "font-size: 18px">Incomplete dominance in _Mirablis jalapa_ $\rightarrow$ Incomplete dominance in _Mirablis jalapa_ $\rightarrow$ <span style = "color:blue"> Flower colour in snapdragon </span> $\rightarrow$ Flower colour in snapdragon $\rightarrow$ Incomplete dominance </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritance Variation L-4 </Success>
### <primary style="font-size:24px"> Flower colour in snapdragon </primary>
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<footer style = "font-size: 18px">Incomplete dominance in _Mirablis jalapa_ $\rightarrow$ Flower colour in snapdragon $\rightarrow$ <span style = "color:blue"> Flower colour in snapdragon </span> $\rightarrow$ Incomplete dominance $\rightarrow$ Feather colour in Andalusian fowl </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritance Variation L-4 </Success>
### <primary style="font-size:24px"> Feather colour in Andalusian fowl </primary>
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<footer style = "font-size: 18px">Incomplete dominance $\rightarrow$ Feather colour in Andalusian fowl $\rightarrow$ <span style = "color:blue"> Feather colour in Andalusian fowl </span> $\rightarrow$ Incomplete dominance $\rightarrow$ Incomplete dominance </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritance Variation L-4 </Success>
### <primary style="font-size:24px"> Incomplete dominance </primary>
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- Andalusian Fowl

- Incomplete dominance in andalusian fowl

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<footer style = "font-size: 18px">Feather colour in Andalusian fowl $\rightarrow$ Feather colour in Andalusian fowl $\rightarrow$ <span style = "color:blue"> Incomplete dominance </span> $\rightarrow$ Incomplete dominance $\rightarrow$ Co-dominance </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritance Variation L-4 </Success>
### <primary style="font-size:24px"> Co-dominance </primary>
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* In Co-dominance, the "recessive" & "dominant" traits appear together in the phenotype of hybrid organisms

* Red × white $\rightarrow$red & white spotted

* In Co-dominance, a cross between organisms with two different phenotypes produces offspring with a third phenotype in which both of the parental traits appear together

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![image](/subject-images/iitpal/image/biology-class-12-unit-05-chapter-04-genetics-evolution-principles-of-inheritance-variation-l-4_7-cks7v9jspfe-26.jpg)
![image](/subject-images/iitpal/image/biology-class-12-unit-05-chapter-04-genetics-evolution-principles-of-inheritance-variation-l-4_7-cks7v9jspfe-27.jpg)

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<footer style = "font-size: 18px">Incomplete dominance $\rightarrow$ Incomplete dominance $\rightarrow$ <span style = "color:blue"> Co-dominance </span> $\rightarrow$ Co-dominance $\rightarrow$ Problem to solve </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritance Variation L-4 </Success>
### <primary style="font-size:24px"> Problem to solve </primary>
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- **Question.** The color of fruit for plant "X" is determined by two alleles. When two plants with orange fruits are crossed the following   phenotypic ratios are present in the offspring - 25% red fruit, 50% orange fruit, 25% yellow fruit

- **Question.** What are the genotypes of the parent orange- fruited plants?

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![image](/subject-images/iitpal/image/biology-class-12-unit-05-chapter-04-genetics-evolution-principles-of-inheritance-variation-l-4_7-cks7v9jspfe-29.jpg)

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<footer style = "font-size: 18px">Co-dominance $\rightarrow$ Co-dominance $\rightarrow$ <span style = "color:blue"> Problem to solve </span> $\rightarrow$ Answer $\rightarrow$ Mechanisms of sex determination </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritance Variation L-4 </Success>
### <primary style="font-size:24px"> Answer </primary>
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- 25% red : 5% orange : 25% yellow

- 1:2:1

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<footer style = "font-size: 18px">Co-dominance $\rightarrow$ Problem to solve $\rightarrow$ <span style = "color:blue"> Answer </span> $\rightarrow$ Mechanisms of sex determination $\rightarrow$ Genetically controlled sex determining mechanism </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritance Variation L-4 </Success>
### <primary style="font-size:24px"> Chromosomal mechanism of sex determination </primary>
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* Types of chromosomes

- Autosomes -22 pairs in humans (A-G groups)

- 1-3 pairs - A group
 - 4-5 - B group
 - 6-12 pairs - C group
 - 13-15 - D group
 - 16-18-E group
 - 19-20-F group
 - 21-22-G group
- Sex chromosomes:XX - Female, XY-Male

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![image](/subject-images/iitpal/image/biology-class-12-unit-05-chapter-04-genetics-evolution-principles-of-inheritance-variation-l-4_7-cks7v9jspfe-33.jpg)

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<footer style = "font-size: 18px">Mechanisms of sex determination $\rightarrow$ Genetically controlled sex determining mechanism $\rightarrow$ <span style = "color:blue"> Chromosomal mechanism of sex determination </span> $\rightarrow$ Karyotype of normal human being $\rightarrow$ XX-XY mechanism </footer>