Topic 3 - Movement into and out of cells

Diffusion

the net movement of particles from a region of high concentration to a region of lower concentration down a concentration gradient as a result of their random movement

Where does the energy from diffusion come from?

comes from the kinetic energy of random movement of molecules and ions

Factors that affect diffusion (4)

-temperature -concentration gradient -surface area to volume ratio -diffusion distance

Why is diffusion important?

all cells rely on diffusion: -for getting raw materials for respiration -for removing waste products -for plants’ use of photosynthesis

Respiration - gas exchange

in breathing you exchange carbon dioxide and oxygen between alveoli in the lungs and the blood. (diffusion)

Osmosis

the net movement of water molecules from a region of high concentration (dilute solution) to a region of low concentration (concentrated solution) through a partially permeable membrane

Turgor pressure

plants are supported by turgor pressure pressing outwards on the cell wall

Active transport

the movement of particles through a membrane from a region of low concentration to a region of higher concentration using energy from respiration

transport proteins use this energy to move nutrients into and out of the cell