Suppose you are designing an experiment to test the effects of nicotine on the heart rate of rats. what are the disadvantages of having too small a sample size (i. e., testing on too few rats)?

The larger the sample size the fewer errors would be made. it also averages out the results. depending on what the experiment is like i.e.: how would ___ nicotine affect the heart rate of 100 rats. your prediction/hypothesis would be closer to the experiment results with a larger test number of say 1000. but with a smaller sample size its hard to accurately predict and have more consistent resulta

Igot the answer, here you go dude. 

Are you referring to tectonic plates?