In order to determine the effect of muscle fatigue on the ability of students to squeeze a clothespin, five male students did jumping jacks for three minutes and then squeezed a clothespin as many times
as possible in a minute. Three other male students ran up and down the stairs for 30 seconds and then
squeezed a clothespin as many times as possible for one minute. The results of the two groups were
recorded. Identify one change that could be made to the experiment to increase the validity of the
conclusion made from these results.

Imagine you are a student in alfred hershey and martha chase's lab in the late 1940's. you are given five test tubes with the e. coli bacteria that were infected with t2 bacteriophage that have been labeled with 32p or 35s. unfortunately, you forgot to label the tubes and are now uncertain which were 32p labeled and which were 35s labeled. you place the contents of each tube in a blender and pulse it for a few seconds to shear off the protein coats from the bacterial outer membranes. you then centrifuge the contents to seperate the protein coats and the bacterial cells. you then check for radioactivity and obtain the results shown below. which tubes contained e. coli infected with the phage labeled with 32p? select all tubes that apply.