1. Unit 2: Multicellular Organisms Topic 6 National 5
TRANSPIRATION
Unit 2: Multicellular Organisms Topic 6 National 5

2. Haileybury Astana IGCSE Science 2018

3. Transpiration – Lesson 1
Learning Intentions
By the end of this lesson I will be successful if I can:
Sate that water is essential for photosynthesis.
Describe the role of root hairs, xylem and stomata in the transport of water in plants.
Give a detailed account of the processes involved in water movement in plant tissues.
Haileybury Astana IGCSE Science 2018

4. Haileybury Astana IGCSE Science 2018
Key words
Photosynthesis
Transpiration
Active transport
Transpiration stream
Osmosis
Minerals
Xylem
Water
Lignin
Phloem
Stomata
Haileybury Astana IGCSE Science 2018

5. Water is needed for photosynthesis!
water + carbon dioxide glucose + oxygen
Haileybury Astana IGCSE Science 2018

6. Haileybury Astana IGCSE Science 2018
Root Hairs
Root hairs project out from the roots into the soil.
Water is absorbed from the soil through the root hairs by osmosis
Haileybury Astana IGCSE Science 2018

7. Unit 2: Multicellular Organisms Topic 6 National 5
Water
Unit 2: Multicellular Organisms Topic 6 National 5

8. Haileybury Astana IGCSE Science 2018
Xylem
Lignin
1 Element of the vessel (remains of one living cell)
Pits
Perforations
Haileybury Astana IGCSE Science 2018

9. Haileybury Astana IGCSE Science 2018
Xylem
Haileybury Astana IGCSE Science 2018

10. Haileybury Astana IGCSE Science 2018
Xylem
Lignin is waterproof.
Lignin is strong and keeps the xylem vessels open.
Haileybury Astana IGCSE Science 2018

11. Haileybury Astana IGCSE Science 2018
Leaf Structure
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12. Haileybury Astana IGCSE Science 2018
Stomata
The thicker, less elastic, inner wall doesn’t stretch as much as the rest of the cell, forcing the cell to curve.
Haileybury Astana IGCSE Science 2018

13. Haileybury Astana IGCSE Science 2018
Closing of Stomata
Guard cells close by losing water.
This happens at night as they do not photosynthesise and do not need carbon dioxide.
This conserves water so the plant does not begin to wilt.
Haileybury Astana IGCSE Science 2018

14. Haileybury Astana IGCSE Science 2018
Stomata
Haileybury Astana IGCSE Science 2018

15. Unit 2: Multicellular Organisms Topic 6 National 5
Stomata
Unit 2: Multicellular Organisms Topic 6 National 5

16. Unit 2: Multicellular Organisms Topic 6 National 5
3. Which cells control the loss of water.
2. Which cells transport water up the stem?
1. Which sort of cells take up water?
Unit 2: Multicellular Organisms Topic 6 National 5

17. Haileybury Astana IGCSE Science 2018
Lesson 1
Learning Intentions
By the end of this lesson I will be successful if I can:
Apply the term water potential to explain the movement of water through a plant
Give a detailed account of the processes involved in water movement in plant tissues.
Haileybury Astana IGCSE Science 2018

18. Unit 2: Multicellular Organisms Topic 6 National 5
Water potential
Water potential is how freely water molecules can move from a place. It is measured in kilopascals (kPa) and is represented by the Greek letter Psi (Ψ). Water potential is never positive but has a maximum value of zero, which is that of pure water at atmospheric pressure
Unit 2: Multicellular Organisms Topic 6 National 5

19. Water potential gradient
Water always moves from a low/high water potential to a low/high water potential.
In the diagram, the highest water potential is found in the _______ and the lowest water potential is found in the ______.
Give the term given to the change in water potential throughout the plant.
State the term used to describe the movement of water up the plant.
Name he process by which water enters the roots of the plants
Unit 2: Multicellular Organisms Topic 6 National 5

20. Haileybury Astana IGCSE Science 2018
Cohesion & Adhesion
The affinity for like molecules is called cohesion.
Water molecules have a affinity for each other and adhere strongly to each other.
Adhesion is the affinity for unlike molecules.
The surfaces of the water molecules that cannot adhere to other water molecules adhere to the molecules of the vessel that they are in.
Haileybury Astana IGCSE Science 2018

21. Haileybury Astana IGCSE Science 2018
Adhesion and cohesion
Partially submerging a glass tube into water allows adhesions to occur with the side of the tube. This combined with the pull of the cohesive forces between water molecules allows the water to rise up the glass tube.
Haileybury Astana IGCSE Science 2018

22. Haileybury Astana IGCSE Science 2018
Lesson 2
Learning Intentions
By the end of this lesson I will be successful if I can:
Identify the vascular bundles in a plant
Describe how a photometer can be used to determine transpiration rates
List the factors that affect the rate of tranpiration
Haileybury Astana IGCSE Science 2018

23. Haileybury Astana IGCSE Science 2018
Draw the diagram above.
Xylem transports _________ and minerals from the _______ to the rest of the plant. _______ transports sugars through the plant. This can occur in _______ directions.
Haileybury Astana IGCSE Science 2018

24. Haileybury Astana IGCSE Science 2018
Potometer
Factors that increase the rate of transpiration:
Light through the opening of stomata,
Warm and dry conditions through increasing the evaporation of water from the leaves.
Haileybury Astana IGCSE Science 2018