Genetic Variation

(Adapted from Alike, But Not the Same, HHMI)


Nicholas J. Caruso

Urban Action Academy

Summer Research Program for Science Teachers

August 2010



Subject:  Living Environment (Biology)

Grade Level: 9 & 10

Unit:  Genetics

Lesson:  Cooperative learning (3 students/group)

Learning Objectives -


  Identify the source of genetic variation in a population.

  Explain how genetic variations are not always harmful.

  Explain how some variations can provide an organism with a survival advantage.

  Explain how most variations do not lead to dysfunction. 



  Pictures of different human families

  Inventory of Few Human Traits and Thinking About Human Variation Worksheets  (masters 1.1-1.2)

  Teacher computer and LCD projector


Background Information: 

The ultimate source of genetic variation is differences in DNA sequences.  Most genetic differences result in variations that do not adversely affect us.  Some differences however result in disease.  Some variations in fact provide some organisms with a survival advantage. 



Each group will be given a picture of a family.  They should not be told that the individuals in the picture are members of the same family. In their group they will answer the following questions:

  What are some ways in which these people appear the same?

  What are some ways in which they appear to be different?

  Are they related? If so, provide solid evidence to support your claim.

Student groups will chart their responses and share with the class. 



Students will use Master 1.1, An Inventory of a Few Human Traits to further identify ways in which we are different. On the projector students will view a picture of a fish, bacteria and a plant. 

Question: If someone from another planet walked into the room would they same that all of you look very much alike?  Students explain.

Question: Are we more like each other than like the fish? Bacteria? Plant? 

Students will begin to work on developing an inventory of traits.  Students will work in teams to chart variations. Once they have completed their inventory, they will use Post-it notes to place their data onto the chart paper. 

Teacher note: On chart paper, construct these diagrams on four separate sheets and put them on the board.  Students will record their data by placing their Post-it note in the appropriate place on each of the axes.


Analysis of results:

1.      What evidence in the data supports the idea that we are similar?

2.      What evidence in the data supports the idea that we are different?

3.      How many traits would we have to consider to identify any student as unique?


Students will work in their groups to complete Master 1.2, Thinking About Human Variation.


Students will look a group of organisms of the same species and develop a concept map relating to their differences and similarities and briefly discuss how the variations may provide them with a survival advantage. 


New York State Standards: 

Living Environment Core Curriculum

Key Idea 3, Performance Indicator 3.1 Major Understandings:

3.1g     Some characteristics give individuals an advantage over others in the surviving and reproducing, and the advantaged offspring, in turn, are more likely than others to survive and reproduce.  The proportion of individuals that have advantageous characteristics will increase.

3.1h     The variation of organisms within a species increases the likelihood that at least some members of the species will survive under changed environmental conditions.