is bladderwort a producer of a consumer. An animal that can't produce its own food and it eats plants and other animals. That is what a consumer is.
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.
Supplement. In scientific experiments, the use of controls allows to study one variable or factor at a time. It is, however, important that both the control and other (experimental) group(s) are exposed to the same conditions apart from the one variable under study.