To be able to compare the results to a sample without any of the independent variable added.
If I'm not mistaken, it leaves through the osculum which is a cavity located on the upper part of a sponge.
Sponges feed through a process called filtration, which means that they filter the water in search of nutrients. And after they collect everything they need from the water, they need to let it out somehow; through the osculum.
Hope it helped,
BioTeacher101
Answer:
because the more alike species are The more they have to adapt to try and compete with one another So the more different a species is the less they have to compete
A cell membrane is compared to a window screen because of its translucent properties. Like it allows oxygen to come through or it resists invader who tries to come into the cell.
Your answer is Cell membrane.