1. Leaf Structure and Photosynthesis
&
Photosynthesis

2. Flowering Plants - Parts
Leaf
Stem
Roots

3. The Leaf
Vein
Lamina
Midrib
Stalk

4. Palisade mesophyll layer Spongy mesophyll layer
Leaf Structure
Waxy cuticle
Epidermis
Palisade mesophyll layer
Air space
Spongy mesophyll layer
Stomata
Epidermis

5. Waxy Cuticle & Epidermis
The waxy cuticle is a thin layer atop the epidermis. Its function is to reduce the water lost from the leaf. In arid conditions this cuticle layer can be quite thick.
Epidermis cells contain no chloroplasts -They form layers on the upper and lower surfaces of the leaf.
Their function is to prevent water getting out and stopping unwanted substances/organisms getting in.

6. Palisade Mesophyll Layer
The palisade mesophyll layer is where most of the photosynthesis occurs in the leaf.
Palisade mesophyll layer
The palisade cells contain a lot of chloroplasts to help them perform this photosynthesis.
The palisade cells are closely packed together to maximize light absorption.
In the leaf cross-section we can see the palisade cells are only found in the upper part of the leaf.

7. Spongy Mesophyll Layer
The cells in the spongy mesophyll layer are loosely packed.
This creates air spaces inside the leaf to enable gases to move in and out.
Spongy mesophyll layer
There are not as many chloroplasts in the spongy mesophyll cells as there are in the palisade mesophyll cells – but photosynthesis still occurs in the spongy mesophyll layer.

8. Stomata There are holes found in leaves called stoma.
These holes allows gases to diffuse in and out of the leaves.
The stoma are formed by two highly specialized epidermis cells.
These cells, called guard cells, are the only epidermis cells that contain chloroplasts.
The stoma open and close depending upon the requirements of the plant.
It is through these stoma that water leaves the leaf, the process that powers transpiration.
Stomata

9. Stomata Stomata open Stomata closed
During photosynthesis carbon dioxide diffuses in and oxygen diffuses out
When the stomata are closed,often at night or in a humid environment, this stops gases diffusing in and out of the leaf

10. Key Words Waxy cuticle Waterproof layer atop the epidermis Stoma
Pores that allow gaseous exchange
Found in the spongy mesophyll layer, enable gases to reach the leaf cells
Air spaces
One-cell thick outer layer of cells that prevent water loss from the leaf
Epidermis
Palisade mesophyll cell
Contain numerous chloroplasts and are densely packed
Loosely packed cells that do not contain as many chloroplasts as palisade cells
Spongy mesophyll cell

11. Photosynthesis
Chloroplasts are organelles of plant cells that contain a green substance called chlorophyll.
Scientists believe chlorophyll absorbs light energy and this energy is then used to make food.
The raw materials of photosynthesis are carbon dioxide and water. The waste product of this reaction is oxygen.
The carbon dioxide required is absorbed through the stoma in the leaves – this is how the oxygen is also removed.
The water required is absorbed by the roots.
The word equation for this reaction is...
The chemical equation for this reaction is...
6H2O + 6CO2  C6H12O6 + 6O2

12. Exercise 2: Label the Parts of a Plant
1. _______
Flower
2. _______
Leaves
3. _____
Stem
4. ______
Roots

13. Exercise 3: Label the Parts of a Plant
Leaf
Roots
Stem
Flower

14. Exercise 4: Leaf Structure
1. ___________
Waxy cuticle
2. ___________
Epidermis
3. ______________________
Palisade mesophyll layer
4. __________
Air space
5. _____________________
Spongy mesophyll layer
6. ________
Stomata
7. __________
Epidermis

15. Exercise 5: Link the Boxes
Pores that allow gaseous exchange
Waxy cuticle
Found in the spongy mesophyll layer, enable gases to reach the leaf cells
Stoma
Waterproof layer atop the epidermis
Air spaces

16. Exercise 6: Link the Boxes
Loosely packed cells that do not contain as many chloroplasts as palisade cells
Epidermis
One-cell thick outer layer of cells that prevent water loss from the leaf
Palisade mesophyll cell
Contain numerous chloroplasts and are densely packed, where most of the photosynthesis occurs
Spongy mesophyll cell

17. Exercise 7: Insert the Missing Words
Chloroplasts are __________ of plant cells that contain a green substance called __________.
Scientists believe chlorophyll absorbs _____ energy and this energy is then used to make _____.
The raw materials of photosynthesis are carbon dioxide and _____. This waste product of this reaction is _______.
The carbon dioxide required is absorbed through the ______ in the leaves – this is how the oxygen is also removed.
The water required is absorbed by the _____.
organelles
chlorophyll
light
food
water
oxygen
stoma
roots
roots organelles light food
water chlorophyll oxygen stoma

18. Exercise 8: Short Questions - Photosynthesis
1. Which organelles in plant cells contain a green substance called chlorophyll?
2. Which two raw materials are required by green plants for photosynthesis?
3. What is the waste product of photosynthesis?
4. How does this waste product leave the plant during the day?
5. What process requires this waste product to enable green plants to release energy from their food?
Chloroplasts
Water and carbon dioxide
Oxygen
Through the stoma
Respiration

19. Exercise 9: Short Questions – Plant Nutrition
1. What do we call the process whereby green plants make glucose using light energy and the raw materials carbon dioxide and water?
2. During the night many green plants perform another process whereby they release the energy from their food they have made. What do we call this process?
3. The sugar glucose, the product of photosynthesis, is changed to starch when it is being stored by the plant. Why?
4. What is the chemical formula of glucose?
Photosynthesis
Respiration
Glucose is soluble in water, starch is insoluble in water. By storing the food starch it means it is easier for the plant to keep the food in the required place
C6H12O6

20. Exercise 10: Short Questions – Plant Nutrition
1. What is the word equation for photosynthesis?
2. What is the chemical equation for photosynthesis?
3. Name the arrowed organelle.
4. Which substance does this organelle contain that allows green plants to absorb the Sun’s light energy for the process of photosynthesis?
6H2O + 6CO2  C6H12O6 + 6O2
Chloroplast
Chlorophyll

21. Regulation of Transpiration by Stomata
Leaf and stem epidermis has a waxy cuticle that is impermeable to water, but also to CO2.
Stomata, or pores, in the epidermis allow CO2 to enter by diffusion.
Guard cells control the opening and closing of the stomata.
Most plants open their stomata only when the light is intense enough to maintain photosynthesis.
Stomata also close if too much water is being lost.