What is the purpose of controlling the environment like testing a hypothesis

Question

anonymous · Answer

I believe the purpose of it is to collect information on the environment, although I'm not sure if that's right

anonymous · Answer

I'm not quite sure I get your question. If it is; What is the purpose of a control in verifying a hypothesis or conducting an experiment, it is:

Controls are needed to eliminate alternate explanations of experimental results. That is in order to test a particular variable you need a control. 

For e.g. In an experiment to show only aerial parts of the plant lose water, you add a layer of oil over a beaker containing water and a plant to ensure that water is not lost through direct evaporation.