2.15 - 2.17 Movement of Substances in Cells

diffusion

the movement of particles from an area of low concentration to an area of high concentration

factors affecting diffusion

surface area, temperature, distance and concentration gradient

where does diffusion occur?

in fluids and doesn’t require energy

particles in diffusion, osmosis and active transport move in and out of a cell through what?

a partially permeable membrane

the greater the concentration gradient

the quicker the rate of diffusion

the larger the surface area to volume ration

the quicker the rate of diffusion

the hotter the temperature

the more kinetic energy the particles will have, so they will move quickly increasing the rate of diffusion

movement of substances that dosen’t require energy is known as a

passive process

osmosis

the movement of water from an area of high water concentration to a low area of water concentration through a partially permeable membrane

animal cell in pure water / dilute solution

the cell will become lysed - cell membrane isn’t strong enough to withstand the pressure, - this process in know as cell lysis

plant cell in pure water / dilute solution

the cell will become turgid - the cell won’t swell up and burst because the cell wall protects them and the vacuole expands and the cell membrane pushes on the cell wall

cells in pure water / dilute solution

as there is a higher water concentration outside the cell thank within, water will move into the cell via osmosis

cells in isotonic solutions

there will be no movement because the concentration of water inside and out are equal

animal cells in isotonic solutions

normal

plant cells in isotonic solutions

flaccid - normal

cells in concentrated solutions

there is a lower concentration of water and therefore water will move out of the cells

animals cells in concentrated soloutions

the cell will become shriveled - loose water from their cytoplasm

plant cells in concentrated solutions

the cell will become plasmolyzed - their vacuoles will shrink and cell membrane will push away from their cell walls - this process is knows as plasmolysis

active transport

the movement of particles from an area of low concentration to high concentration

active transport requires what?

energy

active transport uses energy grained from

respiration

root hair cells

these need to actively transport mineral ions from the soil. they are also specialised which have many mitochondria that provide energy for respiration for the active transport of mineral ions against the concentration gradient into the root hair cells