A cycle is made of two primary components: reservoirs and pathways. A reservoir is a holding place, a part of a cycle where something stays temporarily. It will stay in one reservoir before it is moved to another part of the cycle (another reservoir). Pathways are the processes or mechanisms that cause something to move from one reservoir to another.

answer; both surfaces of the membrane are nonpermeable

answer; /// the shaft of the hair consists of dead cells;

while the heads of the phospholipid structure attract water, the tails are hydrophobic. the model shows how the hydrophilic section folds around the fluid molecules to bring them into the cell so they don’t need to pass through the hydrophobic tails.