Define diffusion and osmosis. Explain how osmosis helps plant leaves remain firm. What is the term for water pressure inside plant cells?

Diffusion is the process by which molecules move from an area of high concentration to one of lower concentration, eventually resulting in the even distribution of the molecules. This movement occurs due to the random motion of the molecules and does not require any external energy. The process continues until the concentration of molecules becomes equal in all areas.

Osmosis is a special type of diffusion that involves the movement of water molecules across a selectively permeable membrane from a region of lower solute concentration to a region of higher solute concentration until the concentrations on both sides of the membrane become equal. This process helps to maintain the balance of water and solute concentration inside and outside the cells.

Plant cells have a rigid cell wall that surrounds the cell membrane. Inside the cell, there is a large central vacuole that stores water and other substances. When there is a higher concentration of solutes inside the cell compared to its surrounding, water moves into the cell through osmosis. As the central vacuole fills with water, it pushes against the cell wall, creating an internal pressure called turgor pressure. Turgor pressure is essential for maintaining the structure and firmness of plant leaves. When a plant has enough water, the turgor pressure inside the cells is high, and the leaves remain firm. If there isn't enough water, the turgor pressure drops, causing the leaves to wilt and lose their firmness.

The term for water pressure inside plant cells is "turgor pressure."