Answer:
It is a group designed to not be affected by any variables and to be used as a comparison to the other groups. It helps increase the reliability of your results, as it shows your independent variable is what made something happen in your experiment.
Answer: 1: allergic disorders
2. Immunodeficiency disorders
3. Autoimmune disorders
4. Cancers
Answer:
Zebra mussels negatively impact ecosystems in many ways. They filter out algae that native species need for food and they attach to--and incapacitate--native mussels. Power plants must also spend millions of dollars removing zebra mussels from clogged water intakes.
Because they are built with overlapping sand and they can break easily.
