If the concentration of phosphate in the cytosol is 2.0 mm and the concentration of phosphate in the surrounding fluid is 0.1 mm, how could the cell increase the concentration of phosphate in the cytosol?

active transportation is required to increase the concentration.

Explanation:

In particular condition, the quantity of phosphate in the cytosol in 2.0 mM and the quantity of phosphate in the adjacent fluid is 0.1 mM. Therefore, phosphate concentration within the cell is lower. If we have to maximize phosphate content in the cytosol, in order to achieve the cytosol, the phosphate from surrounding fluid must be transferred against the concentration gradient. Thus active transportation is required to increase the concentration.

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.