✔ Inheritance :
o Mechanism of transfer of traits/features from parents to offspring either through sexual mode or asexual mode of reproduction.
⮚ Mendel’s Experiments (1856-1863)
o Gregor Mendel experimented on Pisum sativum (garden pea).
o He investigated the inheritance pattern of various traits of pea plant.
o He was the first one to use statistical analysis and mathematical logic to understand mechanisms in biology.
o He used a large sampling size.
▪ He got greater credibility to the data that he collected from the pea experiments.
▪ Sampling size here refers to the use of large number of pea plants to obtain the results of the experiments.
🙞 Why did Mendel selected Pea plant for his experiments?
o Short life cycle of the pea plant.
o Presence of bisexual flowers that help in self-pollination.
o A single pollination can give rise to large number of seeds.
o Presence of seven pairs of contrasting characters
▪ Contrasting characters refers to extreme opposite phenotypic expressions
● For example: Seed color of pea plant can be yellow or green. There is no intermediate color. Only two opposite contrasting seed color.
🙞 Seven pairs of contrasting characters studied by Mendel
|
Sl. No. |
Characters |
Contrasting Traits |
|
1 |
Stem Height |
Tall / Dwarf |
|
2 |
Flower Colour |
Violet / White |
|
3 |
Flower Position |
Axial / Terminal |
|
4 |
Seed Shape |
Round / Wrinkled |
|
5 |
Seed Colour |
Yellow / Green |
|
6 |
Pod Shape |
Inflated (Full) / Constricted |
|
7 |
Pod Colour |
Green / Yellow |
🙞 How did Mendel perform the experiment?
o Mendel conducted many artificial pollination/cross pollination experiments using several true-breeding pea lines.
▪ True breeding line – A plant that has undergone continuous self-pollination for many generation and exhibits an stable trait inheritance and expression for several generations.
● In ither words, in case of true breeding plant line the plant does not loose a trait due to segraegation.
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