AP BIOLOGY

Detailed explanation-1: -If a semipermeable membrane (one that is permeable to water but not a solute) separates pure water from water in which solute is dissolved, water molecules will diffuse across the membrane into the region of higher solute concentration.

Detailed explanation-2: -Some substances, such as gases and water, can pass across the membrane easily by diffusion. However, other substances, such as glucose, need to be transported across the cell membrane. This is why the membrane is partially permeable-it controls which substances can travel across it easily.

Detailed explanation-3: -Osmosis is the diffusion of water molecules, from a region where they are in higher concentration, to a region where they are in lower concentration, through a partially permeable membrane.

Detailed explanation-4: -Therefore, for osmosis to occur, the membrane must be permeable to water, but impermeable to the solute, and the concentration of the solute must be different on the two sides of the membrane.

Detailed explanation-5: -In osmosis, a semipermeable membrane is present, so only the solvent molecules are free to move to equalize concentration.