Photosynthesis is the process by which plants produce their own food, using water, carbon dioxide, and sunlight as raw materials. The byproducts are oxygen and sugars. It occurs in the chloroplasts of plant cells, specifically the mesophyll cells of leaves. Chlorophyll in the chloroplasts absorbs sunlight to drive the reaction that produces oxygen and sugars like glucose. Photosynthesis provides food for heterotrophs and oxygen for all organisms on Earth.

1. Photosynthesis
is a process
whereby green
plants
manufacture
their own food.

2.  Materials used during the
process of photosynthesis
are: water, sunlight and
carbon dioxide.
The by-products are: oxygen
and sugars.

3. Photosynthesis can be summarized
in the following equation:
6 CO2 + 12H2O+ Light energy
C6H12O6 + 6 O2 + 6H2O
(glucose)

4. Who or what photosynthesizes?
 Photoautotrophs can photosynthesize.
 Includes: green plants, algae, cyanobacteria and green
protists

5. The importance of photosynthesis
To provide nutrients and oxygen for heterotrophs.
Heterotrophs are dependent on autotrophs, because
they cannot produce their own food.
Auto means self: troph means feeding
Thus plants are self-feeding organisms meaning that
they make their own food.

6. RAW MATERIALS OF
PHOTOSYNTHESIS
• The raw materials of
photosynthesis are:
 water,
carbon dioxide and
sunlight.

7. Where in the plants does
photosynthesis occur?
 Photosynthesis occurs in the chloroplasts of
plant cells.
 The chloroplasts are mainly concentrated in the
mesophyll cells of leaves.
 Chloroplast contain chlorophyll – green pigment
that absorbs sunlight.
 Chlorophyll fill the space in the thylakoid
membrane.

8. Chloroplast structure

9. HOW RAW MATERIALS REACH THE
CHLOROPLASTS
 Water is absorbed through the root hair into the xylem
of the roots, into the xylem of the stem, through the
xylem of the leaves into the mesophyll cells and finally
into the chloroplasts.
 Carbon dioxide diffuses from the atmosphere through
the stomata, into the intercellular airspaces in the
leaves, and finally into the chloroplasts of the
mesophyll cells.
 The chlorophyll and other pigments in the thylakoid
membrane absorb the solar energy to drive
photosynthesis

10. The function of the stomata in
photosynthesis
A stomata is a pore that is found on the leave.
It plays a vital role in the gaseous exchange;
Carbon dioxide diffuses from the atmosphere
through the stomata into the leave.
Oxygen diffuses from the leaves through the
stomata into the atmosphere.

11. Factors that that causes a change
in the rate of photosynthesis
 Light, concentration of carbon dioxide and temperature.
 With light: less sun= less photosynthesis,
 More sun= more photosynthesis. This is because there is a 'light
dependant reaction' as part of photosynthesis, and therefore
photosynthesis can only happen when there is enough sunlight. The
more the carbon dioxide, the faster the rate of photosynthesis.

12.  Increasing the temperature increases the rate of
photosynthesis. This is because there are enzymes
in the process of photosynthesis.
 Enzymes activity increases with an increase in rate
of the temperature (up to a point, when it is too hot
for the enzymes to work).

13. The importance of photosynthesis
A review
o Photosynthesis produce oxygen into the atmosphere .
o Plants store excess sugar as starch in roots,
tubers, seeds, and fruits.
o Plants produce food by through the process of
photosynthesis.

14. References
 Williamson, J. (2011). Unit 6: Photosynthesis (Process of food
production by plants) PowerPoint Slides. Johannesburg:
University of Johannesburg.
 http://wiki.answers.com/Q/What_is_the_function_of_stomata_in_the
_leaf ( Accessed on 15 October 2012)