1. Movement of Substances
CHAPTER 3
Movement of Substances 1

2. Movement of Substances
Chapter 3
Movement of Substances
3.1 Diffusion
3.2 Osmosis
3.3 Surface Area to Volume Ratio
3.4 Active Transport 2

3. 3.1 Diffusion Learning Outcomes
After this section, you should be able to:
define diffusion; and
discuss the importance of diffusion in nutrient uptake and gaseous exchange in plants and humans. 3

4. 3.1 Diffusion How do particles move?
Think of a time when you detected the smell of perfume in a room. How has the smell travelled to your nose?
Region B with lower concentration of particles
Region A with higher concentration of particles
Movement of particles 4

5. 3.1 Diffusion What is diffusion?
Diffusion is the net movement of particles from a region where they are of higher concentration to a region where they are of lower concentration, that is, down a concentration gradient. 5

6. Concentration gradient
3.1
Diffusion
Concentration gradient
Concentration gradient is the difference in concentrations between two regions.
direction of movement of particles
Point A
Point B
Distance
Concentration
molecules diffuse down a concentration gradient 6

7. How is a concentration gradient related to diffusion?
3.1
Diffusion
How is a concentration gradient related to diffusion?
The movement of fluid particles is diffusion .
Particles will diffuse down their concentration gradient.
The steeper the concentration gradient, the higher the rate of diffusion.
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8. Diffusion of a dissolved substance
3.1
Diffusion
Diffusion of a dissolved substance
A copper sulfate crystal is dropped into a gas jar containing water.
The gas jar is allowed to stand for a few days.
The blue colour gradually spreads throughout the water.
The copper sulfate particles diffuse evenly throughout the water.
gas jar
water
copper sulfate crystal 8

9. Diffusion across a membrane
3.1
Diffusion
Diffusion across a membrane
Both the ___________ and ___________ are able to pass through a _________________________.
potassium iodide particle
permeable membrane
copper sulfate particle
Copper sulfate and potassium iodide particles evenly distributed 9

10. Diffusion of gases in the lungs
3.1
Diffusion
Diffusion of gases in the lungs
______________________ in the lungs occurs via diffusion.
air space in the lungs
lung cell
red blood cell
CO2 diffuses from blood into the lungs
O2 diffuses from lungs into the blood 11

11. Movement of Substances
Chapter 3
Movement of Substances
3.1 Diffusion
3.2 Osmosis
3.3 Surface Area to Volume Ratio
3.4 Active Transport 12

12. 3.2 Osmosis Learning Outcomes
After this section, you should be able to:
define osmosis; and
discuss the effects of osmosis on plant and animal tissues. 13

13. 3.2 Osmosis What is osmosis?
A _______________________________ allows some substances to pass through it but not others.
partially permeable membrane
water molecule
sucrose molecule B A
10% sucrose solution (less water, more sucrose)
5% sucrose solution (more water, less sucrose) 14

14. 3.2 Osmosis What is osmosis?
The partially permeable membrane allows water molecules to pass through but not sucrose molecules.
partially permeable membrane B A
rise in level of solution
drop in level due to movement of water molecules to A 15

15. How can we demonstrate osmosis?
3.2
Osmosis
How can we demonstrate osmosis?
An experiment is set up as shown.
The level of the solution in the thistle funnel is observed to rise.
This is due to water molecules moving into the thistle funnel from the beaker.
thistle funnel
retort stand
sucrose solution
cellophane paper
beaker
water 16

16. What is water potential and how is it related to osmosis?
3.2
Osmosis
What is water potential and how is it related to osmosis?
The ____________________________________ is known as water potential.
A dilute solution has a higher water potential.
A concentrated solution has a lower water potential. 17

17. What is water potential and how is it related to osmosis?
3.2
Osmosis
What is water potential and how is it related to osmosis?
A _____________________________ is established when a partially permeable membrane separates two solutions of different water potentials.
more solute, lower water potential
less solute, higher water potential
partially permeable membrane
water moves down the gradient
water potential gradient established 18

18. What is water potential and how is it related to osmosis?
3.2
Osmosis
What is water potential and how is it related to osmosis?
_____________ is the net _________________
_____________ from a solution of higher water potential to a solution of lower water potential, through a ______________________________.
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19. How does osmosis affect living organisms?
3.2
Osmosis
How does osmosis affect living organisms?
Cells are living ________________________.
Plant cell
Animal cell
partially permeable cell surface membrane
fully permeable cellulose cell wall
enclosed nucleus and cytoplasm containing various dissolved substances 20

20. What happens to a cell in a solution with higher water potential?
3.2
Osmosis
What happens to a cell in a solution with higher water potential?
cell sap has lower water potential than surrounding solution 1
water enters by osmosis 2
in solution of higher water potential
cell sap in vacuole
plant cell
cell expands and becomes __________ 3
cell wall prevents cell from bursting 4 21

21. What happens to a cell in a solution with higher water potential?
3.2
Osmosis
What happens to a cell in a solution with higher water potential?
cytoplasm has lower water potential than outside solution, water enters by osmosis
animal cell
in solution of higher water potential
cell expands and _________ 22

22. What happens to a cell in a solution with lower water potential?
3.2
Osmosis
What happens to a cell in a solution with lower water potential? 1
cell sap has higher water potential than surrounding solution
plant cell
cell sap in vacuole
in solution with low water potential
water leaves by osmosis 2
cytoplasm shrinks away from cell wall and cell becomes _____________ 3
cell becomes ___________ 4 23

23. What happens to a cell in a solution with lower water potential?
3.2
Osmosis
What happens to a cell in a solution with lower water potential?
cytoplasm has higher water potential than surrounding solution, water leaves by osmosis
animal cell
in solution of lower water potential
cell shrinks in size and becomes _____________
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24. What happens to a cell in a solution of the same water potential?
3.2
Osmosis
What happens to a cell in a solution of the same water potential?
A cell immersed in a solution with the same water potential as its cytoplasm _____________________
____________________. 25

25. Why is turgor important in plants?
3.2
Osmosis
Why is turgor important in plants?
Turgor plays an important role in _____________ _____________________ in plants.
It keeps herbaceous (non-woody) plants ________________________________.
Loss of turgidity causes the plant to __________. 26

26. Why is turgor important in plants?
3.2
Osmosis
Why is turgor important in plants?
Changes in turgor also cause the movements of some plant parts, e.g. opening and closing of stomata.
turgor in guard cells causes stoma to open in the day
lack of turgor in guard cells causes stoma to close at night 27

27. Why is turgor important in plants?
3.2
Osmosis
Why is turgor important in plants?
Plasmolysis causes tissues to become limp or ________________.
When cells of a plant become flaccid, the plant _____________.
Water may be added to the soil to dilute the soil solution. This causes water moelcules to enter the plant cells and keeps the plant firm and upright. 28

28. Movement of Substances
Chapter 3
Movement of Substances
3.1 Diffusion
3.2 Osmosis
3.3 Surface Area to Volume Ratio
3.4 Active Transport 29

29. Surface Area to Volume Ratio
3.3
Surface Area to Volume Ratio
Learning Outcomes
After this section, you should be able to:
explain how surface area to volume ratio affects the rate of movement of substances. 30

30. What does surface area to volume ratio mean to a cell?
3.3
Surface Area to Volume Ratio
What does surface area to volume ratio mean to a cell?
The ___________ the surface area to volume ratio, the _____________ the rate of _____________. 31

31. What does surface area to volume ratio mean to a cell?
3.3
Surface Area to Volume Ratio
What does surface area to volume ratio mean to a cell?
Cube
Surface area/cm2
Volume/cm3
Surface area: volume
Cell A1 (side 1 cm)
Cell A2 (side 2 cm)
Cell A3 (side 3 cm) 6 1
_________ 24 8
_________ 54 27
_________
As a cell becomes bigger, its surface area to volume ratio decreases. 32

32. Surface Area to Volume Ratio
3.3
Surface Area to Volume Ratio
food + O2 in
Each shaded square represents a unit volume of protoplasm
waste products out
loss in surface area
Cell A1
Cell A2
Cell A3 X Y Z 33

33. How are cells adapted for the absorption of materials?
3.3
Surface Area to Volume Ratio
How are cells adapted for the absorption of materials?
Cells which function in absorption have an ____________________________________.
For example, root cells have long processes and epithelial cells have a folded cell membrane.
Epithelial cell
Root hair cell 35

34. Movement of Substances
Chapter 3
Movement of Substances
3.1 Diffusion
3.2 Osmosis
3.3 Surface Area to Volume Ratio
3.4 Active Transport 36

35. 3.4 Active Transport Learning Outcomes
After this section, you should be able to:
define active transport;
explain that active transport is an energy-consuming process by which substances are transported against a concentration gradient; and 37

36. What is active transport?
3.4
Active Transport
What is active transport?
______________________ is the process in which energy is used to move the particles of a substance across a membrane _________
_________________, that is, from a region
where the particles are of lower concentration to
a region where they are of higher concentration. 38

37. _______________ against a concentration gradient requires ___________
3.4
Active Transport
______________ down a concentration gradient
_______________ against a concentration gradient requires ___________
higher concentration of solute molecules, e.g. glucose.
lower concentration of solute molecules, e.g. glucose. 39

38. 3.4
Active Transport
Since active transport requires energy, active transport occurs only in ___________________.
Dissolved mineral salts are taken up by root hair cells via active transport.
soil solution
root hair cell
path taken by substances absorbed by root hair cell
mineral salts 40

39. Movement of Substances
Chapter 3
Movement of Substances 42

40. Movement of Substances
Chapter 3
Movement of Substances
The URLs are valid as at 15 January 2014.