Learner Resource 1 – Photosynthesis
By completing this handout, you will have summary notes on the process of photosynthesis.
1.
What does a plant need to carry out photosynthesis?
2.
What is produced by photosynthesis?
3.
What do humans use these products for?
4.
Draw a simple diagram representing photosynthesis:-
The chemical equation for photosynthesis:-
Compare that to the equation for respiration:C6H12O6 + 6O2  6CO2 + 6H2O + energy
5.
Why are we dependent on plants?
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Overview of Process of Photosynthesis:•
Carbon dioxide and water are taken in by plants
•
Plants absorb light energy and convert it to a usable form- ATP
•
Energy is used to “fix” carbon dioxide into sugar molecules (chemical energy)
•
Sugar is converted to starch and stored for use by the plant, and by animals when they
eat plants.
Chloroplasts
6.
Draw and label a chloroplast:-
Chloroplasts are the organelles in the leaf where photosynthesis takes place. They are
positioned in leaves to harvest the maximum amount of light energy.
They contain chlorophyll molecules – a pigment that absorbs sunlight
A system of flattened membranous vesicles – the thylakoids - are located throughout the
chloroplast. These are surrounded by a liquid based matrix – the stroma.
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Photosynthesis consists of two stages –
 The light-dependent stage which takes place on the thylakoid membranes where
chlorophyll is situated.
 The light-independent stage (the Calvin Cycle) which takes place in the stroma
containing enzymes which control the complex reactions.
What happens in the light-dependent reactions:Two useful products are formed by the light-dependent stage – ATP and NADPH
These are needed to drive the light-independent stage.
7.
Using the sorting activity, produce a summary of the reactions that occur during the lightdependent stage.
The light-independent reactions:•
The reactions take place in the stroma of the chloroplasts and form a metabolic
pathway known as the Calvin Cycle.
•
These reactions do not need light but do need the products of the light dependent
reactions. Because of this they cannot go on for long in the dark as the ATP and
NADPH run out.
•
The light independent reactions consist of a cycle which uses up carbon dioxide, ATP
and NADPH.
•
It produces carbohydrate molecules.
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8.
What happens in the light-independent reactions:-
9.
Use the sorting activity to produce your own summary.
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Products of photosynthesis
During photosynthesis carbon dioxide is ‘fixed’ producing glycerate phosphate (GP) and triose
phosphate (TP). GP and TP can then be used to make carbohydrates, lipids and proteins
within a plant.
Complete the following table to explain how GP or TP is converted into carbohydrates, lipids
and proteins:Organic
molecule
Diagram of molecule
Production
mechanism
carbohydrate
Diagram of glucose
(monosaccharide)
carbohydrate
(polysaccharide)
Diagram of amylose and amylopectin
glycerol
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Fatty acids
lipids
Amino acid
Protein
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