Students will distinguish between natural and artificial selection and use a student-centered learning activity to see how science and genetics have been used to artificially select apples for specific traits like color, texture, taste, and crispness.
Apples and the Science of Selection handout, 1 copy per student
Station Cards, 1 copy per class printed front to back
Paper plates, utensils, and napkins as needed for taste testing
Ask students to raise their hand if they have recently eaten a Red Delicious apple. Ask a student to describe what it looked and tasted like.
Ask students to raise their hand if they have recently eaten a Honeycrisp apple. Ask a student to describe what it looked and tasted like.
Continue a class discussion comparing varieties of apples. What qualities make a good apple? What qualities make a poor apple? How many varieties of apples are there? How are different varieties of apples developed? What will apples be like in the future? Can science explain why different varieties of apples taste different?
Conclude your discussion with the final question, "Are apples different today because of something humans have done or because of something that occurred naturally (without human intervention)?" Leave the question open-ended and inform students that you will return to it after the activity.
Preparation: Prior to class, set up five stations around the classroom. Each station should have the supplies listed above in the Materials section of the lesson plan.
Give each student one copy of the Apples and the Science of Selection handout.
Divide the class into 5 equal groups and assign each group a specific station for their first rotation.
Give a brief introduction to students by explaining that they will be rotating through 5 stations. They will have approximately 10-15 minutes at each station to read the station card and complete the three tasks listed on the back. Students will need their handout and a writing utensil to begin.
Set a timer. Consider projecting it in the classroom to allow students to gauge their time at each station. After the time is up, groups should move in a sequential direction. Reset the timer and continue until all groups visit all five stations.
Once students have come back together, re-ask the question, "Are apples different today because of something humans have done or because of something that occurred naturally (without human intervention)?" (They are a result of what humans have done, also known as artificial selection.)
Give each student one copy of the Artificial vs Natural Selection Venn Diagram. Have students identify the differences and similarities between the two forms of selection. If helpful, use the attached Venn Diagram Prompts and instruct students to sort the statements to the correct area of the venn diagram.
Disciplinary Core Ideas: Natural selection occurs only if there is both (1) variation in the genetic information between organisms in a population and (2) variation in the expression of that genetic information - that is trait variation that leads to differences in performance among individuals.
Concept Elaboration and Evaluation:
After completing these activities, review and summarize the following key concepts:
Apples have a long history of importance and selective breeding in the United States.
Most apple trees today are grown through grafting, a method of asexual propagation to reduce genetic variability in apple varieties. This allows every apple of a specific variety to taste and look the same.
In apples, characteristics such as color, texture, sweetness/tartness, juiciness, and crunchiness are determined by the genetic make-up of the apple.
Scientists use a knowledge of genetics and heredity to crossbreed apples (using seed, or sexual propagation) to produce new varieties of apples.
Genetic engineering is a tool used in plant and sometimes animal breeding. One variety of apple, the Arctic® apple, was genetically modified so that it does not brown when it is cut. All other apple varieties were created through crossbreeding and artificial selection.
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Practice grafting with apple trees, bring in a community expert for additional help.
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