Why are we not sick all of time if pathogens are everywhere?

In which case would a scientist choose to use a dissecting microscope rather than a compound microscope

How does the nervous system affect the excretory system?

Will ! a cell containing a 3% sucrose solution is placed into a beaker containing a 7% sucrose solution. assume the cell’s membrane is permeable to water, but not permeable to the sucrose. where will the water diffuse? explain.