transport in cells Flashcards
What is diffusion
The random movement of particles from an area of high concentration to an area of low concentration
How do you calculate net movement
Particles moving in - particles moving out
What is net movement
The general movement of particles
What are the factors that determine the rate diffusion
Concentration gradient, surface area and diffusion distance
How does the concentration gradient affect the rate of diffusion
The greater the concentration gradient the quicker diffusion takes place
How does temperature affect the rate of diffusion
As the gas or solution heats up the particles gain more kinetic energy and move around faster, this increases the random movement of the particles enabling them to diffuse more rapidly
How does surface area affect the rate of diffusion
Our membranes are partially permeable, so by increasing the surface area through which the particles can move through diffusion will be faster
How does size compare to surface area to volume ratio
The larger the organism the smaller the surface area to volume ratio
List 3 adaptions for exchange
Increasing the surface area, so more particles can move at once
Have a short diffusion distance the particles have to travel
Increase the steepness of the concentration gradient to speed up the net flow of particles
How are lungs adapted for exchange
1)a large number of small alveoli creates a large surface area for rapid diffusion of gases
2) A rich capillary blood supply brings french blood to the alveoli maintaining a steep concentration gradient
Ventilation refreshes the air in the lungs to maintain a step concentration gradient
3)a thin alveolar wall gives the shortest diffusion distance for the gasses
How are the small intestines adapted for exchange
1)They have thousands of villi which in turn have numerous microvilli on their surface for large surface area
2) they have rich capillary lood supply to remove absorbed nutrients and maintain a steep concentration gradient
3)the walls are only one cell thick to keep the diffusion distance short
How are plant roots adapted for exchange
1)The tip of the roots are covered in root hair cells which increase their surface area for absorption
2) transpiration in the leaves continuously pulls water up the plant creating a steep concentration gradient
3) there is only a short distance from the edge of the root to the xylem in the middle
How are plant leaves adapted for exchange
1)There are stomata at the bottom of the leaf to allow carbon dioxide to diffuse into the leaf and oxygen out
2) the thin leaf shape minimises the diffusion distance for gasses
3) the air spaces in the spongy layer exposes a large surface area for gaseous exchange
What is osmosis
The net movement of water from a dilute solution to a strong solution across a partially permeable membrane
Osmosis model answer plan
1.Identify the hyper/hypotonic solution
2.State which way the water moves
3โฆ..by osmosis through a partially permeable membrane
4.Describe the result eg swells up / shrivells up