Mendel and Heredity

Gregor Mendel was a scientist and he is considered the father of genetics because he did all kinds of different experiments which allowed people to find out how traits were inherited.

Mendel was known for studying pea plants in his garden and experimenting with them in order to test the traits that would be passed down from one pea plant to another.

The reason that Mendel chose to use the pea plant is because peas can self-pollinate, and cross fertilize, and they have all kinds of different traits that only come in two different forms.

Using the pea plants allowed Mendel to reduce the possibility of the outcomes and to have a better idea of how traits are passed down.

Pea Plants

Mendel studied seven different pea plant traits, the shape of the seed, the color of the seed, how the flower position was, the color of the flower, the shape of the pod, the color of the pod and the length of the stem. He did experiments in three different steps.

First Step

The first step that Mendel made was to make a parent generation of a breeding plant.

He did this by self-fertilizing the plants until he knew that they had the seven different traits that he would study.

He knew for example, that the flowers that were purple, always made purple flowers. The called these plants the P plants for the parent plant.

Second Step

Mendel then produced a second generation of plants by breeding two different breeding parent plants. He called this second generation F1 plants.

Third Step

Mendel did a third step by making a third generation of plants by self-pollinating two of the second generation or F1 plants that had the same or similar traits.


Mendel found that the second generation or F1 plants all produced the same traits even though the two parents had different traits.

Even with the parents having different traits, the offspring always had the same traits.

For example, if he bred a parent plant that was purple with a parent plant that was white, all of the second-generation plants had purple flowers because the purple flower was the dominate trait.

Mendel then found that in the third-generation plants, that 75% of them were purple and 25% of them were white, even though both of the parents had purple flowers.

This happened because of a recessive gene was found in both parents.

Punnett Square

A Punnett Square helps to show dominate genes, with a capital letter and recessive genes with a lower-case level and is written in a chart.

The chart contains boxes and each box is filled in with the gene that is present.

The Punnett Square is similar to this:











This Punnett Square shows that 75% of the offspring will have the dominate P and be purple and that 25% will have the recessive ww and will be white.

Homozygous and Heterozygous

When two of the genes are the same, they are homozygous and when two of the genes are different, they are called Heterozygous.

Facts About Mendel and Heredity:

  • Scientists did not believe in Mendel’s work until after he was dead, and it was later rediscovered.
  • Mendel also experimented with bees, but he felt that they were too hard to work with.
  • When an offspring gets a trait from each parent, this is oftentimes called “Theory of Segregation.”

What Did You Learn?

  • What is the basic unit of heredity called? The basic unit of heredity is called genes.
  • What was another name for Gregor Mendel? Gregor Mendel was also called the father of genetics.
  • What type of plant did Mendel use for his genetics experiments? Mendel used pea plants to learn about genetics.
  • What was interesting about the second generation of F1 plants? All of the second generation of plants had the same traits.
  • What is a Punnett Square? A Punnett Square is a way to determine what type of gene an organism will have.