The document discusses different types of movement across cell membranes: 1) Diffusion is the passive movement of particles down a concentration gradient without using energy. Diffusion is important for photosynthesis, respiration, and nutrient absorption. 2) Osmosis is the passive movement of water through a semi-permeable membrane from a region of higher water potential to lower. In plants, osmosis allows water uptake and maintains turgor pressure. 3) Active transport moves particles against a concentration gradient using energy. Examples given are nitrate ion uptake in root hairs and glucose absorption in the small intestine.

1. Cambridge IGCSE Biology
3- movement in and out of cells
Biology
Cambridge IGCSE Biology

3. 3.1 diffusion
Diffusion is the net movement
of particles from a region of their higher
concentration to a region of their lower
concentration down a concentration gradient,
as a result of their random movement
Extended energy for diffusion comes from
the kinetic energy of random movement of
molecules and ions

4. 3.1 diffusion
Diffusion importance
living organisms obtain most of their
requirements and riding wastes by diffusion
1- photosynthesis get CO2 by diffusion
2- photo synthesis ride producing O2 as
waste by diffusion
3- diffusion is important in gas exchange in
respiration
4- absorb digested food by diffusion
5- insect pollinated flower attract insect by
diffusion

5. 3.1 diffusion
Extended
Investigate the factors that influence diffusion,
limited to
1-surface area,
2-temperature,
3-concentration gradients
4-distance

6. State that water diffuses through
( semi permeable membranes) by osmosis
3.2 Osmosis
Investigate and describe the effects on plant
tissues of immersing them in solutions of
different concentrations

7. Osmosis and plant cells

8. State that plants are supported by the pressure
of water inside the cells pressing outwards on
the cell wall
3.2 Osmosis

9. osmosis is the net movement of
water molecules from a region of
higher water potential (dilute solution) to a region
of
Lower water potential (concentrated solution),
through a semi permeable membrane
3.2 osmosis
Extended

10. In hypotonic solution
Osmosis take place . Water diffuse into cytoplasm through
the semi permeable membrane
Cell become TURGID and TURGOR PRESSURE become
high so the cell will be supported
Extended
3.2 osmosis
Plant cell will not bursts ( be destroyed )
Because the cell wall can protect it
water
pressure acting against an inelastic cell wall

11. In hypertonic solution
Osmosis take place . Water diffuse out of cytoplasm
through the semi permeable membrane
First cell SHRINKS slightly till become FLUCCIDE
Then the cell membrane pulls away from the cell wall
The cell is PLASMOLYSED
Extended
3.2 osmosis

12. 3.2 Osmosis
importance of water potential and
osmosis in the uptake of water by plants
Root hair take in water by osmosis which
depends on the water potential in the soil
So increasing amount of water in the soil
leads to high water potential helps water to
move into the root hair
and vice versa

13. 3.2 Osmosis and animal cells
Animal cell in hypotonic solution
Cytoplasm is more concentrated than
solution so by osmosis water diffuse into
the cell
As more and more water inter the cell then
the cell membrane start to stretch
Eventually the strain is too much and the cell
bursts ( destroyed )

14. Osmosis and animal cells

15. 3.2 Osmosis and animal cells
Animal cell in hypertonic solution
Cytoplasm is less concentrated than solution
so by osmosis water diffuse out of the cell
As more and more water exit the cell then
the cytoplasm shrinks and cell shrivels up

16. 3.3 Active transport
active transport
is the movement of particles through a cell membrane
from
a region of lower concentration to a region
of higher concentration
using energy from respiration

17. What is active transport?

18. 3.3 Active transport
Extended
Examples of active transport
1- Root hair cell
Take in nitrates ions from soil while root hair cell has
high concentration of nitrates comparing with those in
the soil by ACTIVE TRANSPORT
Root hair cell has special transport protein which
pick up nitrate ions from outside the cell
Then change the shape to push nitrate into the
cytoplasm by using energy from respiration

19. How does the kidney work?

20. 3.3 Active transport
Extended
Examples of active transport
2- small intestine
Take in glucose from the lumen of intestine into cells of
villi
3- Kidney tubules