Why mendel chose pea plants

Mendel studied inheritance in peas Pisum sativum. He chose peas because they had been used for similar studies, are easy to grow and can be sown each year. Pea flowers contain both male and female parts, called stamen and stigma , and usually self-pollinate.

Self-pollination happens before the flowers open, so progeny are produced from a single plant. Peas can also be cross-pollinated by hand, simply by opening the flower buds to remove their pollen-producing stamen and prevent self-pollination and dusting pollen from one plant onto the stigma of another. Mendel followed the inheritance of 7 traits in pea plants, and each trait had 2 forms. He identified pure-breeding pea plants that consistently showed 1 form of a trait after generations of self-pollination.

Mendel then crossed these pure-breeding lines of plants and recorded the traits of the hybrid progeny. He found that all of the first-generation F1 hybrids looked like 1 of the parent plants. For example, all the progeny of a purple and white flower cross were purple not pink, as blending would have predicted. However, when he allowed the hybrid plants to self-pollinate, the hidden traits would reappear in the second-generation F2 hybrid plants.

Mendel described each of the trait variants as dominant or recessive Dominant traits, like purple flower colour, appeared in the F1 hybrids, whereas recessive traits, like white flower colour, did not.

Mendel did thousands of cross-breeding experiments. His key finding was that there were 3 times as many dominant as recessive traits in F2 pea plants ratio. Mendel also experimented to see what would happen if plants with 2 or more pure-bred traits were cross-bred.

He found that each trait was inherited independently of the other and produced its own ratio. This is the principle of independent assortment. He may have grown as many as 30, pea plants over 7 years. When the student clicks the Cross button, five offspring grow. Some of the offspring from the plant with round peas have wrinkled peas. A plant with wrinkled peas appears on the screen and students are asked to cross this plant with itself.

As before, when the student drags the plant into one of the Parent boxes, the Cross button appears. When the student click Next, two plants appear on the screen, both with wrinkled peas.

Because the allele that produces wrinkled peas is recessive, the offspring of this cross will all have wrinkled peas. I noticed that sometimes offspring seem to have traits that their parents did not show.

I called the traits that appeared to mask or hide other traits dominant. I called traits that seemed to be hidden recessive.

In this section of the web lab, students experiment with pea plants to try to discover which alleles are dominant and which are recessive. Using four different pea plants, students can cross plants with themselves or with each other to determine dominance.

Which color is dominant, white or purple? This is a pedigree. You can cross plants with themselves or with each other. When a student clicks on one of the plant symbols a white or a black box , the cross button appears. If the student selects two plants, then the two plants are crossed and the offspring appear below. If a student selects only one plant and clicks the Cross button, then the plant self-fertilizes and the offspring appear below.

Students can cross plants as many times as they want before deciding which allele is dominant. Students can explore all seven of the pea traits that Mendel explored in this section. Four pea plants appear in the pedigree and students can select which trait they are looking at with the pulldown menu in the upper left corner of the screen. When students have determined which alleles are dominant, they can record their choices in their notepads by clicking on the View Notepad button.

The Check button allows students to check the answers they have input into their notepads. The following table shows each of the traits and which traits are dominant and which recessive. A diagram of a family history used for tracing a trait through several generations.

Traits that can be hidden in one generation and then appear in the next. Background In this web lab, students experiment with garden pea plants Pisum sativum as did Austrian monk Gregor Mendel Mendel chose to experiment with peas because they possessed four important qualities: Peas had been shown to be true-breeding all offspring will have the same characteristic generation after generation.

Peas exhibit a variety of contrasting traits purple vs. The shape of the pea flower protected it from foreign pollen.