Movement into and out of cells

define diffusion

movement of particles from an area of high concentration to an area of low concentration down a concentration gradient as a result of their random movement

factors affecting the rate of diffusion

• temperature

• concentration gradient

• surface area

• distance

• size of particles

define diffusion

movement of particles from an area of high concentration to an area of low concentration down a concentration gradient as a result of their random movement

factors affecting the rate of diffusion

• temperature

• concentration gradient

• surface area

• distance

• size of particles

express the factors and conditions that affect the rate of diffusion

• temperature: the higher the temperature, the faster the molecules move, and kinetic energy of molecules increases, so more collisions against cell membrane, faster rate of diffusion

• concentration gradient: more concentration = faster rate of diffusion

• distance: smaller distance = faster rate of diffusion

• size of molecules: bigger molecules = slower rate of diffusion

define osmosis

diffusion of water molecules from an area of high water potential to an area of low water potential down a water potential gradient through a partially permeable membrane

animal cell in a high concentrated solution

increase in the size of the cell, which will cause it to swell and burst, water moves by osmosis from an area of high water potential outside the cell to an area of low water potential inside the cell down a water potential gradient through a partially permeable membrane through protein carriers

animal cell in an equally concentrated solution

equilibrium, no change in shape, water potential inside the cell is equal to water potential outside the cell (no net movement of water molecules by osmosis)

animal cell in a low concentrated solution

cell shrinks as water moves by osmosis from an area of high water potential inside the cell to an area of low water potential outside the cell down a water potential gradient through a partially permeable membrane through protein carriers

palnt cell in a high concentrated solution

increase in the size of the cell, vacoule swells and water molecules push the cell membrane against the cell wall increasing turgour pressure, water moves by osmosis from an area of high water potential outside the cell to an area of low water potential inside the cell down a water potential gradient through a partially permeable membrane

plant cell in an equally concentrated solution

equilibrium, no change in shape, water potential inside the cell is equal to water potential outside the cell (no net movement of water molecules by osmosis)

plant cell in a low concentrated solution

cell becomes flaccid and vacoule shrinks as water moves by osmosis from an area of high water potential inside the cell to an area of low water potential outside the cell down a water potential gradient through a partially permeable membrane

what happens if the cell looses more water

the cell membrane separates away from the cell wall and the cell becomes plasmolyed

what is plasmolysis

shrinkage of the cytoplasm in a plant cell, so cell membrane begins to tear away from the cell

define active transport

movement of particles from an area of low concentration to an area of high concentration against their concentration gradient using energy from respiration through protein carriers

why does active transport need energy?

to change the shape of the carrier protein and allow particles to move against their concentration gradient

compare between active transport and diffusion

diffusion:

• passive process

• down concentration gradient

• does not need a membrane

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active transport:

• active process

• against concentration gradient

• needs a membrane with carrier proteins