Science/Strand III/Content Standard 4/High School/Benchmark 2
Benchmark Question: How do new species or varieties
originate through the evolutionary process of natural selection?
Focus Question: How are new populations developed
through natural selection?
Small groups of students
will grow bacterial colonies on agar plates containing a 0.5% concentration
of antiseptic*. Students should transfer the surviving bacteria to agar
with increasing concentrations of antiseptic agar**. When the maximum
concentration is reached (about 15%), some of the original stock colony
(0%) will be transferred directly to another plate with the highest
concentration (15%). Growth on the two plates with the highest
concentration will be analyzed. Students should develop an explanation for
the difference between the two plates (A new population developed through
natural selection when the surviving bacteria was transferred from plate to
plate of increasing concentration)***. Each student will write a lab report
demonstrating that he or she has followed the steps of the scientific
** Only use purchased
bacteria that are acceptable for classroom use.
*** Can be done as a