1. CSEC BIOLOGY MARCH 1, 2016 10DM MRS. HAUGHTON
PHOTOSYNTHESIS
CSEC BIOLOGY
MARCH 1, 2016
10DM
MRS. HAUGHTON

2. So far in Photosynthesis….
From previous classes, students should know:
The definition for photosynthesis
The word equation for photosynthesis
The chemical equation for photosynthesis
The light stage of photosynthesis
The dark stage of photosynthesis

4. Today we will be doing….
At the end of the lesson, students should know
Internal and external structures of the leaf for photosynthesis
The fate of the products of photosynthesis
Conditions necessary for photosynthesis
Limiting factors of photosynthesis
Importance of photosynthesis
Minerals required by plants for proper growth

5. Light and Dark Stages

6. Internal and External Adaptations of the Leaf
The leaf of a plant is the main site of photosynthesis and so is where most food is made for the plant.
The leaf has many adaptations which make them well suited for photosynthesizing.

7. External Features (Outer features)
Broad, flat, thin laminae
Petiole or leaf stalk
Laminae are spaced out around stems so they do not overlap and block sunlight.

8. Internal Features (Inner features)
CO2 enters and O2 diffuse.
Air spaces.
Palisade cells (diffusion and numerous; closely packed).

9. Chloroplasts can move to trap as much sunlight as possible.
Root hair cells absorb water from the soil.
Xylem vessels carry water and minerals from roots to leaves.

10. Internal Leaf Structure

11. Leaf on the Plant

12. Section through the Leaf

13. Details of the Cells in the Leaf Section

14. Detail of One Mesophyll Cell

15. Inside the Leaf Again

16. 16

17. What Happens to the Products of Photosynthesis?
The oxygen produced by photosynthesis will diffuse into the atmosphere for animals to breathe.
But the Glucose, which is the main product, is a very important starting material for all the other nutrients a plant needs.

18. The excess glucose that is made during photosynthesis is stored as the starch grains in the chloroplasts

21. Conditions Necessary for Photosynthesis
Carbon dioxide (diffuses into leaf through stomata).
Water (absorbed from soil by roots).
Sunlight energy (absorbed by chlorophyll).
Chlorophyll (green pigment in chloroplasts).

22. Enzymes (present in chloroplasts).
Mineral elements (absorbed from soil by roots).
Correct temperature (0°C to 40°C for enzymes).

23. Limiting Factors of Photosynthesis
The following are substances and situations that when varied can change how quickly photosynthesis occurs.
They are called limiting factors since they each can slow down the rate of photosynthesis if they are in lower or smaller amounts than the other variables.

24. Light: limits the rate at dusk and dawn and during winter and fall months.
Carbon dioxide: limits the rate during the day in most climates.
Temperature: limits the rate during the winter.

26. Water: limits the rate when water levels are low.
Wavelength of light: the rate of photosynthesis is affected by the wavelength of light. Photosynthesis is fastest in blue and red light and slowest in green and yellow light.

27. Wavelength for Photosynthesis

28. Importance of Photosynthesis
Photosynthesis is directly related to the life and survival of all the other living creatures on earth.
It supplies oxygen for animals.
It is the way that sunlight energy is used by plants to make different nutrients that can animals can obtain by eating the plants.
It supplies energy to plants which they pass on to animals when eaten.

30. Minerals Required by Plants for Proper Growth