c02 movement of substances Flashcards
(9 cards)
Definition of diffusion
Net movement of particles from a region of higher concentration to a region of lower concentration down a concentration gradient. (passive process)
What are the factors that affect the rate of diffusion?
- concentration gradient
- diffusion distance
- surface area to volume ratio
Definition of osmosis
Net movement of water molecules through a partially permeable membrane from a region of higher water potential to a region of lower water potential down a water potential gradient. (passive process)
What happens to plant cells in solution with higher water potential?
Water molecules enter the partially permeable membrane of the cell by osmosis since the cell has a lower water potential than the surrounding solution. The cell expands and increases in length, becomes turgid.
What happens to plant cells in a solution with lower water potential?
Water molecules leave the cell through the partially permeable membrane by osmosis since the cell has higher water potential than the solution surrounding it. The cell becomes flaccid then plasmolysed (cytoplasm and cell surface membrane pulling away from the cellulose cell wall) and shrinks, decreasing in length.
What happens to animal cell in solution with higher water potential?
Water molecules enter the animal cell through the partially permeable membrane by osmosis since the cell has lower water potential than the surrounding solution. The cell expands in length and bursts.
What happens to an animal cell in solution with lower water potential?
Water molecules leave the cell through the partially permeable membrane by osmosis since the cell has higher water potential than the surrounding solution. The cell shrinks in length and becomes crenated.
Why is turgor pressure important in plants?
Keeps stem and non-woody plants firm and upright, plant may wilt due to loss of turgor pressure
Changes in turgor pressure of guard cells causes the opening and closing action of stomata.
Definition of active transport
Energy is used to move particles of a substance through a cell surface membrane against the concentration gradient from a region of lower concentration to a region of higher concentration.
