California Agriculture in the Classroom

Farming, Food, and Heredity

Grade Level(s)

6 - 8

Estimated Time

50 minutes


Students will apply their knowledge of heredity as they develop a breeding plan for a scenario in which they inherit a tomato farm that has been suffering from a blight fungus.


For the teacher:

For each student:

Essential Files (maps, charts, pictures, or documents)

Essential Links


selective breeding: the intentional crossing of two animals or two plants to produce offspring with a desired characteristic

natural selection: the mechanism by which evolution operates saying that individuals who are best adapted to their environment will have a better chance to pass on their genes to their offspring

Background - Agricultural Connections

This lesson is part of the From Genes to Jeans II series which was written to encourage students to hone basic genetic concepts and skills through defined vocabulary, and provided explanations all the while applying the terms to agricultural concepts used in the industry. Other related lessons and activities include:

For thousands of years, people have been domesticating wild animals and plants for food. In the process, people discovered that they would often improve the quality of future crops if they chose to breed the plants and animals that displayed desired characteristics. This is called selective breeding. For example, we didn’t always have separate breeds of dairy and beef cattle. These breeds resulted after many years of selective breeding by farmers and ranchers who chose to breed cattle for either milk or meat production. Selective breeding is used in all areas of agricultural production for both plant and animal crops.

The opposite of selective breeding is called natural selection. It is also commonly referred to as survival of the fittest. Natural selection occurs without human intervention when plants or animals with the characteristics best suited for survival reproduce and therefore pass on their genetic characteristics to the next generation.

Interest Approach – Engagement

  1. Pose the following question to students:
    • "How does heredity affect agriculture or the food we eat every day?"
    • "Think just about apples. Have we always had so many varieties of apples to choose from at the grocery store?"
    • "Is there one variety of apple that you like the best and choose over others?" (Teachers could have a variety of apples on display).
  2. Explain that just like in humans, heredity affects plants and animals. Farmers and scientists work together to use their knowledge of heredity to help provide a safe, nutritious, and plentiful food supply.


  1. It is said that we first eat with our eyes and nose and if something doesn’t look or smell good we are unlikely to taste it. Explain that people have been selecting the best tasting, highest producing, and hardiest plants for thousands of years. This was mainly accomplished by saving the seeds of plants that produced fruits or vegetables with a trait that people liked. For example, your great grandmother may have saved seeds from her sweetest tasting tomatoes and passed these down to younger generations in the family who continued to plant them and save seeds. Refer to the Farming, Food, and Heredity PowerPoint to discuss the example of Teosinte and modern corn with the class. 
  2. Either print out, or have students go online to read the article, What’s the Difference Between a Strawberry and a Strawberry? 
  3. Introduce to students the tomato farm challenge found in the Farming, Food, and Heredity PowerPoint. Use the PowerPoint slides to explain the scenario and concept mapping assignment: Farmers use genetic breeding to create better tasting and better quality produce. Today, you will need to think like a farmer and use your knowledge of genetics because you have inherited great uncle Hector’s tomato farm and the farm has a problem that you must solve. You go to visit the tomato farm and are told that most of the tomato plants have died after being infected by a fungus. The good news is that there are still a small number of remaining tomato plants that don’t seem to be infected with the fungus. From a breeding standpoint, what could you do to keep next year’s tomato plants from being killed by the fungus?
  4. Students may work in groups on their concept maps to determine the best approach to take for breeding fungus resistant tomato plants. After students have completed the assignment you can discuss different approaches that each group took and discuss how some plants are naturally more resistant to certain diseases than other plants. Disease resistance is a desirable trait for plant breeders and farmers. In developing resistant varieties of tomatoes, breeders may select and cross pollinate tomato plants that survived being exposed to early blight fungus. The seeds from these plants would then be planted and the new plants would be exposed to the blight fungus once again to see which of the plants inherited the disease resistant traits from their parents. The resistant plants would be selected and the process would be repeated numerous times to develop a variety of tomato that is consistently resistant to early blight fungus.
  5. Ask students why they think it is important to maintain genetic diversity in a population. How can genetic diversity help when a population of tomato plants is exposed to a new type of disease? A large gene pool usually means that the population will have a better chance of surviving a disturbance in the environment, or a new disease because at least some of the individuals will have inherited a trait that provides them with some resistance to the new disease or an ability to survive new conditions in the environment. Genetic diversity also makes the population less susceptible to inherited disorders which can become a problem with inbreeding.

Concept Elaboration and Evaluation

After conducting these activities, review and summarize the following key concepts:

Suggested Companion Resources


The development of this lesson was funded in 2014 by Monsanto Fund to provide teachers with lessons in science and biotechnology that meet Common Core and Next Generation Science Standards

Executive Director: Judy Culbertson
Layout and Design: Nina Danner


Mandy Garner

Organization Affiliation

California Foundation for Agriculture in the Classroom