1. A graduate student injects 8 rats with a chemical compound commonly found in the environment and finds that all of the rats die within a few days. Eager to publish her results, the student comes to you , her adviser. What would you suggest the student do before publishing his results? Help her design a controlled experiment. State a good hypothesis, describe the experiment , identify the control group, independent, dependent and controlled variables.

2. Lithops are succulent plants that resemble stones. Describe four characteristics of life that distinguish these plants from dead stones they mimic.

3. In early spring, Dr. Tom Wilson notices that there is an equal distribution of long and short stemmed buttercups in the vacant lot across the street from his house as well as in his own backyard. In late summer he notes that there are mostly long stemmed buttercups in the lot, but mostly short stemmed buttercups in his yard. These observations are examples of what biological principle? Develop a hypothesis to explain Dr. Wilson observation.