A food chain is a linear sequence of organisms through which nutrients and energy pass as one organism eats another. ... Food webs consist of many interconnected food chains and are more realistic representation of consumption relationships in ecosystems.
Essentially, a control variable is what is kept the same throughout the experiment, and it is not of primary concern in the experimental outcome. Any change in a control variable in an experiment would invalidate the correlation of dependent variables (DV) to the independent variable (IV), thus skewing the results.
