Water rises up tree from roots to leaves through small tubes. Water has a high surface tension measured by how difficult it is to break the surface of a liquid. As with cohesion, hydrogen bonding causes water to have high surface tension. Unlike most substances, frozen water is less dense than liquid water. If ice was heavier than water, ice would sink and ponds would freeze solid.
Bases are molecules that take up hydrogen ions or release hydroxide ions.
Buffers keep pH steady and within normal limits in living organisms. Buffers stabilize pH of a solution by taking up excess hydrogen or hydroxide ions.