Your teeth
You’re welcome :)
A scientific hypothesis is an educated guess that is made about an observation based on the prior knowledge of the scientist. Hypothesis are always testable.
An hypothesis can be tested through experimentation and it can also be tested through deductive methods.
Answer and Explanation: The excretory system helps the respiratory system by getting rid of carbon dioxide. The respiratory system helps the excretory system by getting rid of CO2 from the body. They both need each other and if one or the other did not exist, we might've not been able to survive. Tis demonstrates how vital they are for the human body.
Nucleus to the ribosomes, I think.