Transport : diffusion osmosis + active transport Flashcards
Diffusion
a net movement of particles through a partially permeable membrane from an area of higher concentration to an area of lower concentration
Diffusion must occur within
a gas / dissolved substance
Net movement
movement of all particles
when molecules are left alone..
they move randomly
diffusion is a __________ process
because it doesn’t require…
passive
energy from the cell, it is random movement of molecules
partially permeable
only lets through smaller molecules such as water
3 factors that affect the rate of diffusion
concentration gradient
temperature
surface area
how does the concentration gradient affect diffusion
larger concentration gradient + higher rate of diffusion)
how does temperature affect diffusion
higher temperature gives particles more energy to move faster
higher temp –> high rate of diffusion
how does surface area affect diffusion
large surface area = more particles can fit around surface
large surface area –> higher rate of diffusion
osmosis
the net movement of water molecules through a partially permeable membrane from an area of higher water concentration to an area of lower water concentration
water concentration
amount of water compared to other molecules , like sugars and salts, dissolved in water
hypotonic
lower concentration of solutes than inside the cell
hypertonic
higher concentration of solutes than inside the cell
isotonic
concentration of solutes is equal inside and outside cell
hypotonic red blood cell
cell bursts because excesses water is being diffused
osmotic lysis
isotonic red blood cell
normal
equal movement of water in and out
hypertonic red blood cell
cell shrivels because of loss of water
crentation
hypotonic root hair cell
normal
water enters cell
turgid
isotonic root hair cell
becomes soft and loose
flaccid
hypertonic root hair cell
cell membrane pulls away from wall, cell loses water
plasmolyzed
a solution with a high water conc
dilute
a solution with a low water conc
concentrated
why can single celled organisms rely only on simple diffusion
they have a large surface area to volume ratio. lots of surface area to diffuse across and not too much volume to travel through
why can large multi cellular organisms not just rely on simple diffusion
small surface area to volume ratio they have several layers of cells between the center and the environment, useful substances take longer to diffuse in and out
what do large multi cellular organisms use instead of simple diffusion
transport systems of tubes and vessels (eg circulatory system)
name a hazard risk and mitigation attempt in the osmosis potato rqp
scalpel, cutting skin, cut away from potato
cork borer, injuring hand, cut potatoes on ceramic tile
independent dependant and control variable in osmosis potato rqp
- conc of sucrose solutions
- change in mass of potato cylinders
- time each cylinder is left in sucrose solution
why did the mass of the potato increase in distilled water
the water conc was higher outside the potato cell, therefore water moves into the potato through osmosis
why did the mass of the potato decrease in solutions with 0.2-1m solutions
the water conc was lower outside the potato cell, so water moves out of the potato
active transport
movement of particles across a partially permeable membrane against the concentration gradient (from low conc to high) requiring energy from cellular aerobic respiration
active transport is a _______ process
active
what proteins are needed in active transport
carrier proteins, they pick up specific molecules and carry them against the concentration gradient
how does the villi use diffusion and active transport to get nutrients into the blood
diffusion is used until equilibrium is achieved . after this glucose moves from low conc (small intestine) to high conc (blood) through active transport. this ensures all nutrients are absorbed from your food
examples of active transport
kidney reabsorbs sodium ions from urine
thyroid gland takes in iodine for production of hormones
definition of an exchange surface
a surface that is adapted to maximize the efficiency of gas and solute exchange
adaptations of exchange surfaces
- large surface area for diffusion to occur
- exchange surfaces usually very thin (short distance of travel)
-permeable to the substance that needs to be exchanged
name 4 exchange surfaces in plants and humans
alveoli
villi
leaves
root hair cell
what features do the villi have that help with diffusion
-good blood supply maintains conc gradient
-thin walls for short diffusion
-large surface area to volume ratio
features alveoli have to help with diffusion
a good blood supply
maintains conc gradient
a layer of moisture helps gases dissolve
large surface area to volume ratio
why might the mass of the potato not change
the partially permeable membrane became damaged
how are gills of a fish adapted to diffusion
- divided into thin layers of tissue forming a large surface area for diffusion
-continual flow of water maintains a concentration gradient
how are leaves adapted for diffusion
They are thin which gives a short diffusion distance
They are flat which provides a large surface area to volume ratio
They have many stomata which allow movement of gases in and out of the air spaces by diffusion
how is the root hair cell adapted to maximize gas exchange
- large surface area to volume ratio
- water stored in vacuole to maintain conc gradient - lots of mitochondria for gas exchange
- thin exchange surface to shorten diffusion distance
