1. Introduction to Photosynthesis
IGCSE Combined Science
Biology

2. How do plants get their energy?
We get our energy by eating food
But plants don´t eat tacos!!

3. Plants can make their own food!
This process is called photosynthesis
Raw Materials
Equipment
Products
Water
Where does it come from?
Where does it need to go?
Sunlight
Glucose (sugar)
Where is this made?
Does it stay there all the time?
Carbon dioxide
How does the plant take it up?
Chloroplasts containing chlorophyll
Where are these found?
Oxygen
How does this escape from the plant?

4. Photosynthesis
Photosynthesis

5. Photosynthesis
Photosynthesis

6. Plants’ uses of plant glucose
Raw material for growth, repair and replacement of damaged parts
Used immediately to provide energy source for respiration
Energy used to turn sugars, nitrates & other nutrients into amino acids which build up proteins
To make fats & oils (energy stored in seeds)
Glucose
Energy stored as sucrose (in fruit)
Energy stored as starch (in leaves, seeds, roots and tubers)
SQA LO
State that green plants make their own food which may be stored as starch.
Interpretation- green plants are able to make their own food.
Green plants make food in the form of sugar.
The sugar made by the plant is either used straight away or converted to starch and stored
To make cellulose, the main structural material in cell walls

7. Group Activity: From little acorns do great oaks grow…
A tree is planted in a meadow. After 20 years it has grown into a big tree, weighing 250kg more than when it was planted.
Where do the extra 250kg come from?
Explain your answer as fully and scientifically as you can.

8. Uses of sugars in plants

9. Tasks for the rest of the lesson!
Look at how you can measure the rate of photosynthesis using a gas sensor and a plant
Use this information to help answer the questions on your worksheet
“Investigating photosynthesis in a broad bean plant”