Ch 2 Movement of Substances Flashcards
Define diffusion.
Diffusion is the net movement of particles from a region of higher concetration to a region of lower concentration without the need for energy.
Factors that affect the rate of diffusion?
- Concentration gradient
- The steeper the concentration gradient, the higher the rate of diffusion. - Diffusion distance
- The shorter the diffusion distance, the higher the rate of diffusion. - SA:V
- The higher the SA:V, the higher the rate of diffusion. - Temperature
Increased temperature = Increased KE of particles = Increased rate of collision= Increased rate of diffusion - Mass of particle
Increased mass = Decreased rate of diffusion - Presence of wind
Presence of wind = Increased rate of diffusion
How does oxygen move into the bloodstream through the human lungs?
Oxygen diffuses down the concentration gradient from the air spaces of the lungs, across the one-cell thick capillary walls into the red blood cells.
How does oxygen move into a plant through the roots?
Oxygen diffuses down a concentration gradient, from the soil into the root hair cell.
Adaptations of the small intestine to increase the rate of diffusion of substances into the small intestine wall?
- Presence of villi - Increased SA:V = higher rate of absorption of substances into the small intestine wall.
- One-cell thick epithelial cell - Shorter diffusion distance = higher rate of absorption of substances into the small intestine wall.
Define osmosis.
Osmosis is the net movement of water molecules from a region of higher water potential to a region of lower water potential through a partially-permeable membrane without the need of energy.
Does a dilute solution have a high/low WP?
High.
Does a concentrated solution have a high/low WP?
Low.
Factors that affect the rate of osmosis.
- Water potential gradient
- The steeper the WP gradient, the higher the rate of osmosis. - Distance that water molecules need to move
- Shorter distance = higher rate of osmosis. - SA:V
- Higher SA:V = higher rate of osmosis. - Temperature
Increased temperature = Increased KE of particles = Increased rate of collision = Increased rate of osmosis
What happens to a PLANT cell in a HIGH WP environment?
- The WP in the environment is higher than that of the plant cell’s cell sap.
- Water molecules move by osmosis from the environment into the plant cell’s cell sap through the plant cell’s PPM, down a WP gradient.
- The plant cell’s vacuole increases in size and pushes the cytoplasm against the cell wall.
- The cell expands and becomes turgid.
- The inelastic cell wall prevents the cell from bursting.
What happens to an ANIMAL cell in a HIGH WP environment?
- The environment has a higher WP than the animal cell’s cytoplasm.
- Water molecules enter the animal cell from the environment by osmosis down a WP gradient.
- The cell expands and bursts. (Becomes haemolysed for red blood cell)
What happens to a PLANT cell in a LOW WP environment?
- Cell sap has a higher WP than surrounding solution.
- Water molecules leaves the cell by osmosis.
- Vacuole shrinks in size, cytoplasm shrinks, cell membrane detaches from the cell wall. The cell becomes plasmolysed.
- Cell decreases in size and becomes flaccid.
What happens to an ANIMAL cell in a LOW WP environment?
- The cell’s cytoplasm has a higher WP than the surrounding solution.
- Water molecules leave the cell by osmosis.
- The cell shrinks and spikes appear.
- The cell becomes crenated.
Define active transport.
Active transport is the process where 1. Energy is used for the transport of particles
2. Against the concentration gradient, from a region of lower concentration to a region of higher concentration
3. Through a partially-permeable membrane
Why is turgor important for plants?
- Keeps the plant firm and upright.
- Loss of turgidity will make the plant wilt.
- Turgid guard cells remain curved and keep the stomata open, allowing CO2 to be absorbed for photosynthesis.
