Biology - Movement of molecules Flashcards
diffusion
movement of particles from a region of high concentration to low concentration down a concentration gradient.
passive process
no energy is required since it goes down the concentration gradient
osmosis
movement of water from a high water potential (dilute solution) to a low water potential (concentrated solution) through a partially permeable membrane.
active transport
movement of particles against the concentration gradient from a region of low to high concentration.
active process
requires energy (ATP) from respiration and protein “pumps” located in the cell membrane.
diffusion : importance
- getting raw materials for respiration
- removing waste products
- photosynthesis in plants (raw mat in, waste prod out)
osmosis : importance
- helps with plant support by moving water between plant cells
- when plant is in high water potential environment, absorbs water via osmosis
- vacuole swells pushing against cell wall supporting plant
- cell becomes turgid
turgid
firm and swollen.
factors affecting diffusion (and osmosis)
- higher temperature
- distance (short diffusion paths)
- the concentration gradient (steepness)
- surface area
SA:V (effects)
- larger surface area allows more substances to diffuse in/out faster.
volume (calc)
height x width x length
surface area (calc)
6 x length²
CORMS
C - change (independent variable)
O - organism (control variable linked to the organism)
R - repeat and calculate the mean
M - measure (dependent variable and how you will measure it)
S - same (control variable and how you will control them (3))
independent variable
the one that you change (e.g. temp)
dependent variable
the one that you measure (e.g. height of a plant)
visking tubing prac
- DIFFUSION prac
- diffusion through a partially permeable membrane.
- allows smaller glucose (monomers) to diffuse through but keeps bigger starch (polymers) inside.
thistle funnel prac
- OSMOSIS prac
- shows how water moves through a partially permeable membrane from a dilute solution to a concentrated solution.
agar prac
- DIFFUSION prac
- investigates how SA:V affects the rate of diffusion in cells.
flaccid
water lost from cell, vacuole shrinks.
potato prac
- OSMOSIS prac
- shows how water moves in and out of potato cells depending on the concentration of the surrounding solution
