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Modeling Mendel's Pea Experiment

By Jeanette Nolin



Type of Entry:

  • lesson/class activity

Type of Activity:

  • hands-on activity
  • simulation
  • inquiry lab
  • group/cooperative learning

Target Audience:

  • Biology
  • Genetics, Biotechnology


Abstract

This modeling activity allows students to discover for themselves what Mendel uncovered in his famous pea experiments. It is an excellent introduction to Mendelian genetics which generates discussion and stimulates interest in Mendel's principles. Students are encouraged to use the same observation and critical thinking skills that Mendel used.

Time does not permit us to duplicate Mendel's actual experiment. But real garden peas are placed in foil "pods" to simulate the real pea pods that Mendel grew. Students first make predictions on which type of peas will be found in the "pods". Then they open the pods and count the round/wrinkled peas found in the "F1 pods". They repeat this procedure with the "F2 pods".

The activity can be adapted for various levels and numbers of students. Cooperative groups can go through the activity and write a "scientific paper" to present to the class. Individual or pairs of students could also be used. Lower level students may need more input from the teacher.


Background

By modeling Mendel's pea experiments, students will form their own explanations for the result of crossing a true-breeding round pea plant with a true-breeding wrinkled pea plant (the F1 generation) and for the results of allowing an F1 pea plant to self pollinate (the F2 generation). They will then compare their explanations to Mendel's own conclusions.

It might be helpful to give a brief background of Mendel's life before this activity so that Mendel becomes more real to the students. Also, discuss why he did his experiments using peas and provide information on the anatomy of the pea flower as well as cross and self pollination.

This activity is very easy to adapt to almost any level of student. With low level students, it may be necessary to guide them through each step and have the class discuss each of their hypotheses and the results of each generation of pea pods observed. With higher level students, have them work in small groups of 3 to 4 to develop a "scientific paper" which they later present to the "scientific community" (the rest of the class).

Preparation time for this activity will probably be about one hour. Peas must be separated into smooth and wrinkled peas and then wrapped in foil "pods". The activity itself takes anywhere from 20 minutes (for teacher guided version) to 60 minutes (for student group version). This does not include the pre-activity discussion on Mendel's background.


Project

Materials:

  • garden peas (purchased at local garden/feed store)
  • aluminum foil

Teacher Preparation-

For each group of students prepare pea "pods". Cut foil into 10 squares (3 cm x 3 cm). Take 5 squares of foil and place 4 smooth pea seeds into each square. Fold foil around the seeds to form the pea "pods". Label these "F1 pods". Count out 5 wrinkled pea seeds and 15 smooth pea seeds for the F2 generation. Divide them among the remaining 5 squares of foil and fold to form the pea "pods". Label these "F2 pods".

Student Activity-

Tell the students they will begin by examining the pea pods produced by crossing a true-breeding round pea plant with a true-breeding wrinkled pea plant. These offspring are known as the first filial (F1) generation. Before opening the pea "pods", students should record their predictions for what the seeds will look like. After they've done this you might want to go around the room and ask groups to share their hypotheses.

Next, have students open the pea "pods" and record the number of round and smooth seeds found and then determine the percentages. They should also suggest possible explanations for what they find. If desired, have students share their results with the class before moving to the next step.

Now inform the students that one of the pea plants from the F1 generation is allowed to self pollinate, and the plants that grow from this are known as the second filial (F2) generation. Have students make another prediction on how these seeds will look. You may want to have student share these hypotheses also.

Finally, students should take the pea "pods" produced from the F2 and open them. Count and record these results and determine the percentage of round vs. wrinkled peas. Depending on the level of the student, either discuss these results and the possible explanations as a class or have each group formulate their own analysis/conclusion and prepare a presentation of their findings to present to the "scientific community" (the class).


Individual or Group Assessment Form:

Hypothesis for F1: __________________________________________



            Number of Peas in Pod
            1      2       3       4      5        Total      %        

Round                                                          
Wrinkled                                                                


Possible explanation for results: ___________________________
_____________________________________________________________



Hypothesis for F2: ___________________________________________




            Number of Peas in Pod
            1       2       3       4      5       Total        %    

Round                                                                  

Wrinkled                                                         

Possible explanation for results: ___________________________
_____________________________________________________________


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