In about 13,000 years are summers in the northern hemisphere will be in december and our winters will be in june this change is due to
a. precession b. increasing fall equinoxes c. an increase in earth's rotation right now d. an increase in earth's revolution rate

All cells need water to survive. in order to maintain the necessary amounts, water can flow across the cell membrane from areas of higher concentration to areas of lower concentration. what is this flow of water called? a) active transport b) allocation c) diffusion d) osmosis