Diffusion, Osmosis, Active Transport Flashcards
What is diffusion?
The spreading out of particles resulting in a net movement from a high concentration to a low concentration
Why is diffusion a passive process?
Doesn’t require energy to take place
What is equilibrium?
A stable state where the numbers of particles are balanced
What four factors affect the rate of diffusion?
Temperature
Surface area
The difference between concentrations
What diffuses in and out of a cell?
In - food (nutrients), oxygen
Out - carbon dioxide, waste
What diffuses into and out of the lungs?
O2 diffuses out of the alveoli and into the blood supply
CO2 diffuses out of the blood and into the alveoli to be exhaled
What are the four features of lungs for diffusion?
- many alveoil -> increase surface area
- thin membrane -> decrease distances gases must diffuse
- circulation/breathing -> maintain concentration gradients
- blood supply close to the alveoli -> reduces distance gases must diffuse
What is diffuses in the kidneys?
Urea diffuses into the blood plasma and travels to the kidneys
What diffuses in the small intestine?
Products of digestion diffuse across the membrane of the small intestine and into the blood so they can be used by the body
What 3 features does the small intestine have for diffusion?
1) . Very long and folded - ensure that there is enough time for nutrients to be absorbed as food passes through
2) . Inner layer of tissue folded into finger like projections - increases surface area over which diffusion occurs
3) . Each finger has blood vessels - nutrients only need to diffuse a short distance to rwach the blood ie speeds it up
What are fish gills made up of?
Folded, layered tissue
What do the fish have for gas exchange
- A good blood supply close by
- A thin membrane
- gill fillaments with tiny lamellae increase SA
What is counter current flow - fish? What does it explain?
The bloood supply flows in the opposite direction to the water.
Explains why there is always a lower concentration of oxygen in the blood than the water
What does counter current flow ensure?
Oxygen continually diffuses into the blood
What do leaves diffuse?
O2 for photosynthesis, CO2 diffuses out as a waste product
What are the four features leaves have for diffusion?
1) . Many leaves- increases surface area
2) . Think membrane- shorter distances for gases
3) . Guard cells - control whether the stoma are open or closed
4) . Spongey mesophyll layer - full of air pockets which allows gas to diffuse quickly
What is surface area to volume ratio?
How close the internal parts of the object are to the surface
What is Osmosis?
Diffusion of water from a high concentration (a dilute solution) to a low water concentration (a concentrated solution) through a partially permeable membrane
Is osmosis a passive process?
Yes it doesnt require energy
What is a partially permeable membrane?
Like the cell membrane it doesnt let all types of particles through
What does a partially permeable membrane have?
Pores/gaps within it which control the movement of particles from one side to another
What happens to cells in a solution with a higher water concentration than them?
They will burst and it is a Hypotonic solution
What happens to cells in a solution with the same water concentration than them? What is the solution called?
They will remain the same
Isotonic solution
What happens to cells in a solution with a lower water concentration than them? What is the solution called?
The cell shrivels up and is a Hypertonic solution
What 3 ways does a athelets body change while exercising?
- uses up much of the glucose in their body during respiration
- athelete generates heat as they respire more
- they sweat more to try to cool themselves down (results in loss of water and mineral ions)
What is Active Transport?
Moves substances from a more dilute solution to a more concentrated solution, against a concentration gradient. It requires energy from respiration.
What are the 5 steps in the process of active transport?
- needs special carrier proteins in a cell membrane
- particle to be transported gravbed by the carrier protein
- carrier protein given energy from a molecule (ATP)
- carrier protein rotates and releases the particle to the other side
- carrier protein rotates back and can transport another
How can the effectiveness of an exchange surface be increased?
1) . Having a large surface area
2) . A membrane that is thin, to provide a short diffusion path
3) . (In animals) having a efficient blood supply
4) . (In animals) for gaseous exchange being ventilated
What does active transport allow?
Mineral ions to be absorbed into plant root hairs from very dilute solutions in the soil, as it requires ions for healthy growth
What does active transport allow sugar molecules to do?
To be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration, sugar molecules are used for cell respiration
what sort of molecules can’t fit through cell membranes
starch and proteins
what does it mean if there is a larger surface area of a membrane?
- the faster the diffusion rate as more particles can pass through at once
what happens when there is a lower concentration of nutrients in the gut than in the blood?
active transport allows nutrients to be taken into the blood despite the conc gradient being the wrong way round, glucose can therefore be taken into the bloodstream when its concentration in the blood is higher in the gut
how are alveoli adapted to exchange substances?
- an enormous surface area
- a moist lining for dissolving gases
- very thin walls
- a good blood supply
What are the size of stomata controlled by?
Guard cells - they close the stomata if the plant is losing water faster than its being replaced, without guard cells the plant would wilt
