Plants
Lab 8
Photosynthesis


The Earth is an open system that
requires energy input from the sun.
This energy is channeled into
organic molecules via
photosynthesis.
Photosynthesis



Photons of light arrive at the Earth’s
surface and are absorbed by
pigments in the chloroplasts of
algae and plants.
Photosynthesis makes glucose and
oxygen from carbon dioxide and
water.
6 CO2 + 12 H2O
Sunlight
C6H12O6 + 6 H2O + 6 O2
Photosynthetic Pigments

Pigments are molecules that
absorb some photons in the light
spectrum, and reflect others.

Colors in plants are produced by the
reflection of the light waves that are
not absorbed.
Photosynthetic Pigments


Chlorophyll a and chlorophyll b
are green pigments found in
chloroplasts.
Anthocyanins produce blue, purple,
pink and dark red and are not
involved in photosynthesis.


Water soluble
Carotenoids produce yellow,
orange & bright red. Located in
chloroplasts.
Isolating Plant Pigments

Paper Chromatography
is a technique that allows
us to isolate plant
pigments based on
solubility.




Chlorophyll a (yellow-green)
Chlorophyll b ( blue-green)
Carotenes (orange-yellow)
Xanthophylls (yellow)
Leaf Anatomy

Mesophyll cells are the cells that
perform photosynthesis.
Leaf Anatomy



Mesophyll cells require carbon
dioxide to photosynthesize and
must get rid of oxygen.
Stomata are openings in the leaf
surface that allow gas exchange.
Each stoma is surrounded by guard
cells.
Tropisms

Tropisms are directional growth
responses of plants to external
stimuli.


Phototropism – plant grows toward
light. (roots away, shoots toward)
Gravitropism – plant grows in
response to gravity.