B3 - diffusion + osmosis + active transport Flashcards
define diffusion
movement of particles from a region of higher concentration to the region of lower concentration down the concentration gradient as a result of their random movement
define concentration gradient
difference in region of higher concentration and a region of lower concentration
what is the relationship between the concentration gradient and rate of diffusion
steeper the concentration gradient, faster rate of diffusion
explain diffusion
particles from a region of higher concentration will have more kinetic energy which allows them to move freely and randomly in all directions and diffuse to a region of lower concentration
what are the factors of diffusion
-temperature
-concentration gradient
- distance
- surface area to volume ratio
how does temperature affect the rate of diffusion
higher temperature, more kinetic energy, more movement of particles, faster rate of diffusion
how does distance affect the rate of diffusion
less thickness of cell membrane, faster rate of diffusion
how does surface area to volume ratio affect the rate of diffusion
higher surface area to volume ratio, faster rate of diffusion
note: therefore usually diffusion is faster in small organisms than big ones
define osmosis
net movement of water molecules from a region of higher water potential to a region of lower water potential down a concentration gradient through a partially permeable cell membrane
what is the relationship between solute concentration and water potential
high solute concentration, low water potential
define solute
substance dissolved in a solvent
define solvent
substance that a solute dissolves in
define solution
solute + solvent
define concentrated solution
high solute concentrated
define diluted solution
low solute concentration
define partially permeable cell membrane
a cell membrane that allows some substances through but not others
define net movement
total movement
define equilibrium
no net movement
define isotonic, hypertonic, hypotonic
-isotonic - equal solute concentration = equal water potential
- hypertonic - higher solute concentration - lower water potential
- hypotonic - lower solute concentration - higher water potential
hypertonic solutions in plants: its affects on the plant cell?
-net movement is in
-vacuole increase because internal pressure increases (turgor pressure) so turgid
-cytoplasm and cell membrane are pushed against cell wall because of vacuole size
isotonic solutions in plants: its affects on the plant cell?
-no net movement (water moves in and out)
-vacuole is same because internal pressure (turgor pressure) is the same
- cytoplasm and cell membrane are same
hypotonic solutions in plants: its affects on the plant cell?
-net movement is out
-vacuole decrease because internal pressure decreases (turgor pressure) so flaccid
-goes through plasmolysis
define plasmolysis
cytoplasm and cell membrane rips away from the cell wall
2 importance of water potential in plants
- support and keep the plant upright
-brings water and minerals into root hair cell
hypertonic solutions in animal: its affects on the animal cell?
-net movement is in
-goes through haemolysis
-cytoplasm increases and then comes out of cell
isotonic solutions in animal: its affects on the animal cell?
-no net movement
-cell membrane and cytoplasm stays the same
hypotonic solutions in animal: its affects on the animal cell?
- net movement is out
-goes through crenation - cytoplasm decreases in size
define hemolysis
cell membrane bursts
define crenation
cell membrane shrinks
2 importance of water potential in animals
- keeps cell shape
- keeps it fully functioning
define passive
does not require cells energy from respiration
which 2 process are passive
diffusion, osmosis - they go down the concentration gradient
define active transport
movement of particles through a cell membrane from a region of lower concentration to the region of higher concentration up a concentration gradient using energy from respiration
4 key points about active transport
-goes up a concentration gradient
- uses energy from respiration
-always need a cell membrane
- requires special protein carriers to transfer molecules from 1 side to another
explain how active transport if used in root hair cells
- mineral ions (solutes) are higher inside the cell than out so minerals cannot be absorbed by diffusion or osmosis as they occur down a concentration gradient.
- special protein carriers transfer the mineral ions into the cell using energy from respiration
- so there is an even more lower water potential in the cell so water can water enter by osmosis
what does root hair cell need to have to do active transport
lots of mitochondria for reparation to releases energy for active transport
give an example of active transport in humans
in the small intestine, glucose enters the body using active transport
Explain why the red dye diffuses into the agar jelly
(This is diffusion, not Osmosis) The concentration of red dye if higher outside the cube, the movement of diffusion is from a region of higher concentration to a region of lower concentration down a concentration gradient through the random movement of particles so the red dye diffuses into the agar jelly.
define active
require the cells energy
