1. 1. Glucose may be converted into insoluble starch for storage.
B2 Photosynthesis: mesophyll, respiration, chlorophyll, chloroplasts, walls, absorbs, carbon dioxide, insoluble, oxygen, storage, glucose, light, water, fats, proteins, oils, nitrate, cellulose
Uses of glucose
1. Glucose may be converted
into insoluble starch
for storage.
2. Plant cells use some glucose during respiration.
(glucose + oxygen carbon dioxide + water)
3. Some glucose can
be made into fats
and oils for storage.
4. Glucose can be used
to make cellulose, which
strengthens plant
cell walls.
5. Glucose can used
with nitrate ions from
the soil to make proteins.
Photosynthesis
Plants and algae use light energy to make their own food. The word equation for photosynthesis is…
carbon dioxide + water glucose + oxygen
The role of chlorophyll
Inside the leaf, mesophyll tissue contains many chloroplasts. Chloroplasts contain chlorophyll which absorbs light energy needed for photosynthesis.

2. 1 2 1 2 1 2 2 1 Light intensity Limiting factors
B2 Photosynthesis and limiting factors
Lighting, carbon dioxide, photosynthesis, limiting factor, temperature, increasing, yield, profit, light, increases, enzymes,
Light intensity
As the amount of light increases, so does the rate. The limiting factor is light.
Here, increasing the amount of light has no affect on the rate. The limiting factor is now carbon dioxide or temperature. 1 2
Limiting factors
The rate of photosynthesis may be limited by:
1. Shortage of light
2. Low temperature
3. Shortage of carbon dioxide
In reality all 3 factors interact and any one of them can be a limiting factor.
Carbon dioxide 1
As the amount of carbon dioxide increases, so does the rate. The limiting factor is carbon dioxide.
Here, increasing the amount of carbon dioxide has no affect on the rate. Light or temperature is now the limiting factor. 2
Temperature
Greenhouses
For optimum plant growth farmers may need to control light, temperature or carbon dioxide. This can be done by using artificial lighting, heaters/ventilation and addition of carbon dioxide. Increases in yield must be balanced against the costs involved if farmers are to make a profit. 1
As temperature increases, so does the rate because photosynthetic enzymes work best in the warmth. Here, the limiting factor is temperature.
Most plant enzymes are destroyed at about 45°C. Here, photosynthesis stops and the rate falls to zero.
rate of photosynthesis 2 2 1
0oC
temperature
45oC