diffusion Flashcards
(10 cards)
what is diffusion?
the net movement of particles from an area of high concentration to low concentration down to a concentration gradient.
what main factors affect diffusion?
concentration gradient- larger gradient, faster diffusion.
temperature- higher temperature, faster diffusion.
surface area- larger surface area , faster diffusion
give examples of substances transported by diffusion into the lungs and kidney?
lungs- oxygen diffuses into the blood into the lungs and carbon dioxide diffuses into the lungs from the blood.
kidney- urea diffuses from the cells into the blood plasma.
how are single-celled organisms adapted for diffusion
large surface area to volume ration. maximising the rate of diffusion of molecules to meet the organisms needs
What are some substances that are transported into cells by diffusion?
Take in substances like glucose and oxygen (gas exchange) for respiration in gas exchange
What are some substances that are transported out of cells by diffusion?
-CO2 from gas exchange
-The waste product urea from cells into the blood plasma for excretion in the kidney
-Waste products need to be remove
what is passive
process where no E is required
Why do organisms stop growing after a certain stage?
-Organisms stop growing after they reach a certain stage because if their volume increased more required substances may not be able to reach cells in the inside and their surface area wouldn’t be big enough for their volume
Why can’t cells grow enormous?
Cells can’t grow enormous because there wouldn’t be enough accessible substances
What is the SA:V ratio for unicellular organisms?
-Unicellular organisms have a relatively large SA:V ratio - allows sufficient transport of molecules into and out of the cell to meet the needs of the organism
-When the surface area to volume ration is large, there is a lot of surface area for diffusion and not much volume to travel through
-Therefore, organisms can get all the substances it needs by simple diffusion
