When the concentration of molecules on both sides of a membrane is the same, the molecules will A move across the membrane to the inside of the cell
B stop moving across the membrane
C move across the membrane is both directions
D move across the membrane to the outside of the cell

B. Stop moving across the membrane.

Explanation:

Movement of molecules across the cell membrane depends on the concentration of the molecules on both sides of the membrane i.e the higher the concentration of molecules,the higher the attraction,since the molecules have the same concentration on both sides of the membrane the molecules does not move to either of the sides.

the nitrogen cycle provides nitrogen to the ecosystem from the atmosphere, ground and oceans. nitrogen is an important component of complex molecules such as amino acids and nucleotides, which lead to the creation of proteins and dna, the building blocks of all life. plants absorb nitrogen in the form of ammonium, nitrate ion and, on rare occasions, as amino acids. animals receive nitrogen necessary for biological processes from feeding on living or dead organic matter.