GED Science Practice Test: The Beginning of Genetics: Mendel’s Pea Experiments

Our modern understanding of how traits may be inherited through generations comes from the principles proposed by Gregor Mendel in 1865. Mendel, an Austrian monk with training in statistics, used the common pea plant to study the inheritance of traits. Mendel was curious about how traits were transferred from one generation to the next, and carried out a famous series of experiments that explored inheritance of seven different characteristics in the pea plants. Mendel observed that each of the seven characteristics had two distinct forms, as shown below:

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Mendel started his experiment by creating populations of plants that had only one form of a given trait; he verified the purity of his plants by confirming, for example, that tall plants produced only tall children and grandchildren and so forth.

Mendel then set up a series of experiments with each of the seven traits where he took two pure-bred plants that had different forms of a single trait – e.g. a pea plant with purple flowers and a pea plant with white flowers – and bred them together. These two parent plants, called the P generation, yielded offspring that all looked like one of the two parents – in the flower color example, all of the offspring in this new generation, known as the F1 generation, had purple flowers. These F1 plants, being the offspring of parents with different forms of the trait, were considered to by hybrids.

Mendel then proceeded to cross two plants from the F1 generation with one another and observed traits in their offspring, known as the F2 generation. He found that within the F2 generation, plants with both forms of the trait appeared – and that regardless of which of the seven traits he studied, about ¾ of the plants in the F2 generation had the same form of the trait as the plants in the F1 generation, and about ¼ of the plants had the other form of the trait. An example of this (flower color) is shown below; Mendel observed the same inheritance pattern with the other 6 traits he observed.

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