Diffusion and Osmosis

SQA questions

W hat you should know - diffusion

• In diffusion, a substance will move ( d_____) from an area of h_____ concentration to an area of l__ concentration

• Dissolved f___, o_____, c_____ d_____ and w_____ enter and l_____ the cell by diffusion

• Diffusion allows the e_________ of m________ e.g. o_______ and g________ move into cells and carbon dioxide moves o___

Giffuse

igh

ow

ood xygen arbon ioxide

ater eave

xchange

aterials xygen lucose

ut

C

Glucose and oxygen

_______ by diffusion___________

leaves the cell by

_________

carbon dioxideenter

diffusion

membrane

=

==

The cell membrane c______ diffusion – the passage of substances i____ and o__ of the c___The cell membrane is s_________ permeable – s______ molecules can pass through the p_____ in the membrane

ontrols

nto

ut ell

electively

mall

ores

glucose

waterstarch

What you should know - osmosis

• Osmosis is a s______ case of d_______• In osmosis w____ molecules move from a

h___ w____ concentration to a l__ w____ concentration across a s__________ permeable membrane e.g. the cell m_________ or v______ t_______

pecial iffusion

ater

igh ater ow ater

electively

embrane isking ubing

Examples of osmosis

1

Y

X

If a cell(X) with 5% glucose solution is surrounded by a 10% glucose solution(Y), in which direction will osmosis occur ?

= 5%

= 10%glucoseWater moves ____ of cell from ___ to

____ because X has ___ % water

(HWC) and Y has ___ % water (_____)

out X

Y 95

90 LWC

2 If cell(A) with 2% salt solution is next to a cell(B) with 1% salt , in which direction will osmosis occur ?

A = 2% salt

Water diffuses from cell B _____to cell A ____

by__________.

Cell B has____% water

Cell A has _____% water.

osmosis

HWC

99

LWC

98

X = 5% SALT

In plant cells X and Y there is an ______concentration

water (___%) and therefore

there is no net or ________ movement of

water i.e. water ___ = water ___

equal

95

overall

in out

B = 1% salt

Y = 5% SALT

3

COsmosis in plant cells

same water

concentration

low water

concentration

high water concentration

No change

Water ___ = Water in out

lasmolysed

Water e_____ the cell by o______. Vacuole swells up and cell becomes t______. The c___ w____ prevents b________

W_____ leaves the cell by osmosis. Vacuole s______ and the m_________ is pulled a___ from the cell wall. Cell is p__________.

enters

smosis

urgid

cell all

ursting

ater

hrinks

embrane

way

C Osmosis in animal cells e.g. Red Blood Cells

Animal cell behave differently due to the absence of a

_______cell wall

high water

concentration

Animal cells gain water by ________ ________and ________

___________

water ___ = water ___

no changesame water

concentration

Cells _____ water by

_______ and ______

lose

osmosis shrink

osmosis

burst

low water

concentration

in out

b

swell up

high concentration

low concentration

Dissolved food

oxygen carbon dioxide

Cell membrane

osmosis

atmosphereMuscle cells

diffusion

osmosis

0.9

No gain or loss of water at this concentration / No osmosis at this concentration / No change to cells at this concentration / They look like the untreated cells

Cells have shrunk or crinkled up or shrivelled up

Water has moved out of cell to a lower water concentration /Water has moved out of cell down a concentration gradient

osmosis

water moved out of cell from a high to low water concentration / water moved to a lower water concentration outside the cell / water moved from a higher water concentration inside the cell

oxygen / glucose / amino acid

Shrink and wrinkle

Swell up and burst

losthigher

Which is a turgid cell?

allows exchange of materials /allows water to diffuse into root/ allows glucose to diffuse into cell /