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| Monohybrid Cross |
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| In the first experiment, Mendel considered only one trait at a time. Some of the traits he considered were the height, flower colour, shape of the seed, etc. First he ensured that he had pure-bred tall and pure-bred short plants by selecting seeds from plants that had been self-pollinating for many generations. (Self-pollination is ensured by keeping the flower covered with plastic till seed formation). He selected one tall and one short plant from the pure-breds. He called this the P or parental generation. He cross-pollinated the tall and short plants. In the first generation, he got all tall plants. This generation was called the first filial or F1 generation. Then the plants from F1 generation were self-pollinated and the next generation was called the second filial or the F2 generation. In this generation, the ratio of tall to short plants was found to be 3:1. Of the tall plants, one-third was found to breed true and the other two-thirds on selfing again produced plants in 3:1 ratio of tall and short plants. |
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| The plants that are produced in the F1 generation are called hybrids as they have a mixture of traits of both the parents. Since, in this case only one trait, i.e., height was considered, this cross is called the monohybrid cross. |
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| Phenotype and Genotype |
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| Phenotype refers to the externally exhibited trait whereas genotype refers to the combination of genes or the genetic constitution. |
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