2. Chapter Outlines
Define photosynthesis
Write overall chemical equation for
photosynthesis
Explain light absorption spectrum
Name the photosynthetic pigments
Describe the structure of
chloroplast
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3. 1 hour
st
• By the end of lesson, students should be
able to:
• give the overall outline of photosynthetic
process that leads to the production of
glucose
• list and explain the photosynthetic
pigments involved in photosynthesis
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4. 6.1 WHAT IS PHOTOSYNTHESIS?
Photosynthesis is the process whereby
light energy is converted to chemical
energy that is stored in glucose or
other organic compounds
In the present of light, green plant
produce organic compounds and oxygen
from carbon dioxide and water
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6. PHOTOSYNTHETIC PIGMENTS
Photosynthesis occurs in the
chloloplasts in which chlorophylls are
the most important pigments
In the centre of the chlorophyll ring is a
magnesium atom
At the peripheral location of the ring is
a long hydrocarbon tail that can be
associated with the hydrophobic region
of the thylakoid 10membrane17 18 19 20
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9. PHOTOSYNTHETIC PIGMENTS
These chlorophylls absorb blue and red
lights
Other accessory pigments absorb light
between the blue and the red
wavelengths and transfer the energy to
the chlorophylls
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10. ABSORPTION SPECTRUM
A graph of a pigment’s light absorption
versus wavelength is called an absorption
spectrum
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11. CHROMATOGRAPHY
Chromatography is a technique
used to separate mixtures into
their components
For photosynthesis, a paper
chromatography is commonly
used
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12. The steps involved are as follows:
1. The chlorophyll mixture is dissolved in a suitable
solvent
2. Drops of the resultant solution are repeatedly
placed on top of each other to form a small
concentrated spot near on end of a paper strip
3. A line is drawn across the paper to mark the
position of the spot
4. When the solvent front moves up the paper and
about 1 cm from the end, a line is drawn to mark
the position4 of 7 8 9 10 11 12 13 14front 18 19 20
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the solvent 15 16 17
13. Rf VALUE
The position of various pigments are
marked
The Rf value of a solute / pigment is
calculated using the formula
Rf = distance moved by solute
distance moved by solvent front
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16. Chloroplasts
Any green part of a plant has
chloroplasts
The color of a leaf comes from
chlorophyll, the green pigment in the
chloroplasts
Chlorophyll plays an important role in
the absorption of light energy during
photosynthesis
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17. Chloroplasts are found mainly in mesophyll
cells forming the tissues in the interior of
the leaf
O2 exits and CO2 enters the leaf through
microscopic pores, stomata, in the leaf
Veins deliver water from the roots and
carry off sugar from mesophyll cells to
other plant areas.
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19. Each chloroplast has two membranes
around a central aqueous space, the stroma
In the stroma are membranous sacs,
the thylakoids
- These have an internal aqueous
space, the thylakoid lumen or
thylakoid space
- Thylakoids may be stacked into
columns called grana
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