Mendelian genetics refers to the principles of inheritance as described by Gregor Mendel, an Austrian scientist who conducted groundbreaking experiments with pea plants in the mid-19th century. Mendelian genetics laid the foundation for our understanding of how traits are passed from one generation to the next.

I introduce freshmen biology students to this concept by explaining how Mendel’s plants had very specific traits. Pea plants could be tall or short, green or yellow, have purple or white flowers. I show them a model of a flower and explain how plants can self-pollinate or cross pollinate.

Through a series of experiments, Mendel established general principles on how traits or inherited. He is even known as “The Father of Genetics!”

The slides I show students cover the basics of his experiment and introduces basic concepts, like genotype and phenotype. We learn how to set up a Punnett square, and use the square to predict the outcome of a cross. Students are also introduced to the concept of heterozygous and homozygous.

I keep a whiteboard word wall to help students throughout the unit. Each day, we practice the terms.

Gene / Allele Heterozygous / Homozygous Genotype/Phenotype

Practice Set on Pea Plants

Once students have learned the basics of genetics and how to create a Punnett square to predict outcomes. I have several practice sets for them to complete.

In “Peas, Please,” the focus is on the specific traits Mendel studies. Students practice assigning genotypes (PP, Pp, or pp) to different traits based on whether the trait is dominant or recessive. They set up Punnett squares, and determine the phenotypic ratios of the offspring.

There are many sets to practice, 8 on the first page and 8 on the second. I will assign the first page, and use the second page for students that need additional help. In my experience, some students get setting up the squares right away. Other students take a little longer to figure it out. Use the second page as an optional page for students who need additional help.

Additional Practice Sets on Mendelian Genetics

Bunny Genetic Crosses with two traits – basic crosses, uses Punnett squares

Practice Punnett Squares with Skinny Pigs – hairless guinea pigs are the result of a recessive gene (Key, TpT)

Horse Genetics – basic practice worksheet on monohybrid and dihybrid crosses, using a gait trait found in horses

Fruit Fly Genetics (Vg) – practice worksheet on vestigial wing flies (recessive trait)