14. Which of the following best distinguishes primary succession from secondary succession?
a. The presence of light
b. The presence of water
c. The presence of soil
d. The presence of oxygen

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

Molecular models of two different substances are shown below. in the molecule on the left, the oxygen atom pulls on electrons more strongly than the hydrogen atoms. in the molecule on the right, the two oxygen atoms pull on the shared electrons with the same strength. water molecule, h,o oxygen molecule, oz when the two substances are put in the same container, they do not attract each other. why does this happen? a. they both contain oxygen. b. one is polar and one is nonpolar. c . they are both polar. d. they contain different elements.

Most animal cell membranes have proteins that pump. ions out of the cell and potassium ions into this