Question

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

Short answer

Diffusion is the movement of molecules from an area of high concentration to one of lower concentration, while osmosis is the movement of water molecules across a selectively permeable membrane from a region of lower solute concentration to a region of higher solute concentration. Osmosis helps plant leaves remain firm by allowing water to move into plant cells, filling the central vacuole, and creating "turgor pressure" against the cell wall, thus maintaining the structure and firmness of the leaf. The term for water pressure inside plant cells is "turgor pressure."

Step-by-step solution

Definition of Diffusion

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.

Definition of Osmosis

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.

Role of Osmosis in Maintaining Plant Leaves Firmness

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.

Term for Water Pressure Inside Plant Cells

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