Acell is a complex system. like most systems, a cell contains a boundary that separates things that are inside the system from those that are outside of the system. which part of the cell functions as a system boundary

After getting the slide and microscope ready, stella is eager to see the microscopic pond water specimen! she crouches around her microscope and aligns her eye with the microscope’s eyepiece. but she's only able to see a bright white light. at this point, no specimens or cells are visible on stella's pond water slide. after taking a moment to collect her thoughts, stella realizes she can't see any lifeforms because .

During endocytosis, cells expel what they don't need take in what they need shrink due to loss of water

Which beat describes the brain stem