Plants

1
Plants

• Lab 8

2
Photosynthesis

• The Earth is an open system that requires energy
  input from the sun.
• This energy is channeled into organic molecules
  via photosynthesis.

3
Photosynthesis

• Photons of light arrive at the Earths 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 C6H12O6 6 H2O 6 O2

Sunlight
4
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.

5
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.

6
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)

7
Leaf Anatomy

• Mesophyll cells are the cells that perform
  photosynthesis.

8
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.

9
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.