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2.1 outline the experiments carried out by Gregor Mendel
outline the experiments carried out by Gregor Mendel
- Mendel needed to control fertilisation. Self-fertilisation was ensured by placing a bag over the flowers to make sure pollen from the stamens lands on the carpel of the same flower. Cross-fertilisation was ensured by cutting off stamens from a flower before pollen was produced, then dusting the carpel of the flower with pollen from another plant. To ensure reliability, Mendel used thousands of plants in each experiment.
- Mendel worked with true-breeding plants: self-fertilised plants which produced all offspring identical to the parents.
- Mendel first cross-fertilised two true-breeding plants for one characteristic, for example tall plants were crossed with short plants (Mendel called these plants a P1 parent generation).
- The offspring produced are called F1 (1st filial) generation.
- The F1 generation were then self-fertilised or cross-fertilised to produce a second generation, F2.
Each of the seven traits that Mendel studied had a dominant and a recessive factor. When two true-breeding plants were crossed, only the dominant factor appeared in the first generation. The recessive factor appeared in the second generation in a 3:1 (dominant : recessive) relationship.