Diffusion

Question 1

what are the factors affecting rate of diffusion?

Answer 1

temperature
surface area
concentration gradient
State

Question 2

what is diffusion?

Answer 2

diffusion is the net movement of particles in a liquid or gas from an area of high concentration to an area of low concentration

Question 3

what does diffusion eventually result in?

Answer 3

an equilibrium

Question 4

why does diffusion slow down after a while?

Answer 4

because as diffusion continues the concentration gradient gets less steep

Question 5

why does stiring increase diffusion rate?

Answer 5

when you stir you give the particles more kinetic energy

Question 6

give some examples of diffusion in organisms?

Answer 6

In the lungs oxygen diffuses out of the alveoli into the capillaries and carbon dioxide diffuses in

In the small intestine digested food is absorbed through the membrane of the villi

In the gills of fish water containing oxygen passes through the mouth and over the gills the oxygen diffusing into the blood stream and carbon dioxide into the water

The roots take up water and mineral ions

In the leaves of plants carbon dioxide diffuses through the stomata for photosynthesis whilst oxygen and water vapours move out through them

Question 7

how is the small intestine adapted for diffusion?

Answer 7

-the small intestine has lots of villi that increase the surface area
-these villi also are one cell thick so they provide a very short diffusion pathway

Question 8

how are the lungs adapted for diffusion?

Answer 8

-has millions of alveoli which increase surface area
-alveoli and capillary walls are extremely thin
-there is also an efficient blood supply so the concentration gradient is always steep

Question 9

how are the roots adapted for diffusion?

Answer 9

-have root hair cells which increase surface area
-have lots of mitochondria (active transport)?

Question 10

how are the leaves adapted for diffusion?

Answer 10

-the leaves have a flattened shape which increases the surface area
-the leaf is very thin for a short diffusion path
-air spaces in the spongy mesophyll allows gases to diffuse into pallisade cells
-has stomata which allows gases into the leaf

Question 11

how are the gills adapted for diffusion?

Answer 11

-they contain lamellae to increase surface area
-they have efficient ventilation in water so a steep concentration gradient is maintained