Plant nutrition

What is photosynthesis?

Plants make carbohydrates from carbon dioxide, and water, using light as an energy source.

What is the word equation for photosynthesis?

carbon dioxide + water—>glucose + oxygen

What is the balanced equation for photosynthesis?

6CO2+6H2O→C6H12O6+6O2

What is chlorophyll?

• It’s in the chloroplasts of some plant cells

• It transfers energy from light energy into carb energy

Where is glucose made, and what is it’s function?

• Made in photosynthesis

• Used to release energy in respiration

What are the uses of glucose?

• Starch for energy storage

• Cellulose for cell walls

• Sucrose for transport

• Other sugars for nectar

What are the other uses of glucose?

• To make amino acids and proteins using nitrogen from nitrate ions

• To make chlorophyll using nitrogen and magnesium ions

How are leaves adapted for photosynthesis?

• Large S.A to capture sunlight energy and to increase carbon dioxide absorption from the air

• Stomata on the lower surface to allow carbon dioxide to diffuse into air spaces to the cells in the palisade mesophyll layer, where most photosynthesis takes place

How do you test a leaf for starch

• Boiled to break down cell membranes

• Heated in alcohol to remove chlorophyll

• Then iodine solution is added

Why do we use the starch test?

• To show that leaf or leaf parts without light, chlorophyll or carbon dioxide can’t photosynthesise to make starch.

• Controls are needed so we can compare results

What can we use to measure photosynthesis rate?

An aquatic plant. By counting the number of bubbles given off in a unit of time, or measuring the volume of gas given off in a period of time.

What other factors can the aquatic plant be used to measure?

Used to investigate the effects of altering light intensity, temperature, or carbon dioxide concentration on the photosynthesis rate.

What is a limiting factor?

An environmental factor that is in short supply and when we give more of it the plant photosynthesises faster.

What are limiting factors for photosynthesis?

Light intensity, carbon dioxide concentration and temperature.