2.15-2.17 movement in and out of cells

Question 1

Define the term diffusion

Answer 1

movement of particles from an area of high concentration to an area of low concentration

Question 2

Define the term osmosis

Answer 2

movement of water molecules from an area of high water potential to an area of low water potential across a semi-permeable membrane

Question 3

Define the term active transport

Answer 3

the movement of molecules from an area of low concentration to an area of high concentration across a semi-permeable membrane against a concentration gradient

Question 4

Which factors affect diffusion?

Answer 4

Temperature (the higher the faster)

Surface area to volume ratio (larger surface area faster smaller volume faster)

Concentration gradient (the steeper the faster)

Question 5

How do you calculate surface area?

Answer 5

the area of each face and add them together

Question 6

How do you calculate volume?

Answer 6

multiply length times width times height

Question 7

How do you compare surface area to volume?

Answer 7

Divide surface area by volume to find the ratio

Question 8

PRACTICAL (investigating osmosis)

Answer 8

1- use a cork borer to cut five potato cylinders of the same diameter

2-use a scalpel and ruler to cut each cylinder to the same length

3-measure the mass of each cylinder and record your results in a results table

4-measure 10cm^3 of each sugar or salt solution into each boiling tube making sure to label it correctly going up by 0.25 Mol/dm^3 everytime

5-add one cylinder and leave for a specific amount of time

6-remove potatoes and plot dry & record final mass

Question 9

Interpreting results

Answer 9

(water always moves from a higher to lower water concentration)

-Decreased mass means net osmosis out of cell (water concentration higher out of cylinder)

-Increased mass means net osmosis into cell (water concentration higher in cylinder)

-Same mass means no net osmosis (same water concentration in and out of cylinder)