adding a few more drops of soap to the cup and replacing the liquid in the
syringe.) Placing the disks under vacuum more than three times can damage the
8)pour the disks and the solution from the syringe into the labeled plastic cups
8) Place all 4 cups under a light bulb for 10 minutes
9) At 60 second intervals, count the number of disks floating in each cup.
An example is AP Lab 6, Molecular Biology. Lab 6a demonstrates bacterial transformation using E. coli and the pAMP plasmid. Students are given a step-by-step procedure. The analysis consists of four questions: #1 is a cell count; #2 is a comparison; #3 leads students through a calculation of the transformation efficiency; and #4 is open-ended and asks students to discuss factors influencing transformation efficiency. Lab 6b is called “Restriction Enzyme Cleavage of DNA and Electrophoresis.” Students are told to conduct the lab following directions provided either by their teacher or by the kit they are using. Students do not perform their own digest; they merely load DNA that has been digested for them. They are provided with a photo of a gel carrying size markers and asked to represent graphically the relationship between migration rate and fragment length. They then analyze their own gels to determine the size of their fragments by measuring the migration rates.
The AP manual (Educational Testing Service, 1999) suggests that “since one-fourth to one-third of the credit in comparable college courses is derived from laboratory work, AP courses should likewise emphasize laboratory work.” There are 12 recommended laboratory exercises: