Biology - HOT Science Lab

Teacher
ii. What does it mean when two organisms are very similar The more
similar, the closer related they are and the more recent the common
ancestor is.
iii. List and describe at least two ways that similarity between organisms
can be determined. Comparing anatomy, Comparing DNA,
Comparing embryology (development before birth).
iv. Compare and contrast a cladogram (branching tree diagram) with a
pedigree (family tree). Both show relatives & ancestors. Cladograms
include more distant relatives over a longer period of time and can
thus be used to predict the characteristics of common ancestors.
Extension:
Introduction to classification, phylogenetic trees, and cladistics by UCMP: "What did T.
rex taste like" -
http://www.ucmp.berkeley.edu/education/explorations/tours/Trex/index.html
Cladistics is a Zip—Indiana EDU: http://www.indiana.edu/~ensiweb/lessons/clad.bag.html
Go to the following website http://www.pbs.org/wgbh/evolution/change/family/index.html
and do the activity from PBS called, All in the Family. Questions on this activity are found
in the activity itself. When tree is completed check for correctness.
o Click on each organism that you think are the two closest relatives. The pictures will
appear on an evolutionary tree.
o The remaining species will move into position on the remaining branch and you will
find out if your first guess was correct.
o Use the tools to compare anatomical, developmental, and molecular traits.
o Figure out which traits are primitive (they are the ones held by the out-groups).
o Assume that traits that aren‘t primitive must be derived.
o Find the two organisms that share the most derived traits.
o Drag organisms to put this pair in the top two branches of the tree.
o When you think the tree is correct check the answers.
Additional Resources:
In this lesson, classification can (and should) be used to illustrate more than a mere hierarchical
grouping of organisms. This lesson introduces students to the building of cladograms as
evolutionary trees, showing how "shared derived characters" can be used to reveal degrees of
relations. Students are introduced to the process of illustrating evolutionary relationships with
branching diagrams called cladograms. Students learn that once a cladogram has been
constructed for a group of organisms, it can be used to answer all kinds of interesting questions
based on the shared inherited features of those organisms.
The concepts are as follows:
All living things are related by common ancestry.
Branching diagrams, called cladograms, are used to illustrate evolutionary relationships.
Cladograms are based on shared, inherited features.
Cladograms refine our ability to understand and interpret evolutionary history.
Biology HSL Page 97
Curriculum and Instruction