1. REACTIONS of PHOTOSYNTHESIS 8-2
REACTIONS of PHOTOSYNTHESIS 8-2

2. An chemical equation tells what happens in a chemical reaction when molecules interact.
NaOH + HCl → NaCl + H20
______________ _______________
Molecules that react Molecules that are
produced →

3. Research into PHOTOSYNTHESIS began centuries ago with this
simple question:
When a tiny seed grows into a
huge plant, where does all the
“new plant” come from?

4. EXPERIMENTS TO FIND OUT
a Belgian physician ___________________ determined the mass of a pot of dry soil
and a small seedling.
Jan van Helmont
Then he planted the seedling in the pot and watered
it regularly. At the end of 5 years the _____________
__________about 75 kg, but the mass of the _________ was almost ________________.
seedling had
gained
soil unchanged
He decided the “increase in plant” had to come from
the ________… that was the only thing he had added!
WATER

5. EXPERIMENTS TO FIND OUT
Van Helmont didn’t realize
the major contribution to
the mass of his tree
was something he
couldn’t see…
__________________ from the air.
carbon dioxide
Plants use _______ and ______ dioxide to make ___________________
water
carbon
Carbohydrates

6. EXPERIMENTS TO FIND OUT
1771- An English minister,
_________________________,
discovered that a flame burning
in a closed jar would die out.
If he placed a __________ in the
jar and allowed a few days to
pass, the candle could be lit again.
Joseph Priestley
live plant
The plant produced something
“required for burning” that the candle used up
OXYGEN
We now know it was …____________

7. EXPERIMENTS TO FIND OUT
1779-
Dutch scientist ________________________
showed Priestley’s plant experiment only
worked if the plant was exposed to _________________ !
Jan Ingenhousz
light

8. EXPERIMENTS TO FIND OUT
1961- American chemist ________________________
received the Nobel prize for
figuring out the
chemical _______________
used by plants to make sugar
Melvin Calvin
pathway

9. THE BIG PICTURE → These experiments led to work by later
scientists who finally discovered that in the
presence of light, plants transform CO2 and water
into carbohydrates and release oxygen.
_____________ + ____________ _______________ + ____________ →
_____________ + ____________ _______________ + ____________

10. In addition to water and carbon dioxide, __________________ and
are needed for photosynthesis to happen.

11. PHOTOSYNTHESIS Light-Dependent Reaction oxygen Light & Water
ATP
NADPH
(CH2O)n
Carbon Dioxide
Light-Independent Reactions
Calvin Cycle

12. PHOTOSYNTHESIS: Reactants & Products
LIGHT ENERGY
6CO2 + 6H2O
SUGAR + 6O2

13. Myth:
Many people think that plants are green because they absorb and use green light in photosynthesis,
BUT
Image from:

14. BUT… We “see” reflected light
Light wavelengths that are ___________
off of objects bounce back to our eyes .
That is the ___________ we “see”
Image modified from:

15. absorbs ALL except This book “looks BLUE” because the dye in
this cover _______________ of the
wavelengths of light _________ blue.
_______ light is
____________ to your eyes and it
looks BLUE
absorbs ALL
except

16. The dye in this T shirt absorbs all of the
colors __________________________
Red wavelengths are
_________________ to
your eyes and the
shirt looks RED
GO CATS!

17. Objects “look BLACK” because black dye ________________ of the
wavelengths of light.
When wavelengths are absorbed so is
the_____________ of the wave.
That is why wearing a black T-shirt in the summer feels warmer than wearing
a white t-shirt.

18. The dye in white objects _____________ of the wavelengths of light.
_______ energy is ABSORBED
so wearing white
clothing is “cooler”.

19. Which wavelengths of light are these Flowers REFLECTING?
Images by: VanderWal

20. Which wavelengths of light do these LEAVES reflect?
So green leaves ____________ the
green wavelength
of light.
Image by: VanderWal

21. Plants gather the sun’s energy with light absorbing molecules called ___________.
By: VanderWal

22. (These look yellow, orange, and red)
The main energy
absorbing molecule
in green plants is
___________________
_________________
are plant pigments too.
(These look yellow, orange, and red)

23. GREEN leaves have BOTH chlorophyll AND carotenoids __________________
but the huge amount of chlorophyll ______
the other colors and
leaves usually
look green

24. In ______, chlorophyll production slows as the trees shut down and photosynthesis stops for winter.

25. carotinoid colors that are usually _______ by chlorophyll
Then we can see the
carotinoid colors that are usually _______ by chlorophyll

26. There are two types of chlorophyll
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There are two types of chlorophyll
__________________ & ___________________
Absorption of Light by
Chlorophyll a and Chlorophyll b
Chlorophyll a
absorbs the
_____ & ________
wavelengths best.
It absorbs very
little ______ light.
violet
red
Chlorophyll b
Chlorophyll a
red
Blue

27. There are two types of chlorophyll
© Pearson Education, Inc. Publishing asPearson Prentice-Hall. All rights reserved.
There are two types of chlorophyll
__________________ & ___________________
Absorption of Light by
Chlorophyll a and Chlorophyll b
Chlorophyll b
absorbs some
______light and
even more
_________ light.
red
Chlorophyll b
Chlorophyll a
Blue-violet
red

28. NEITHER KIND OF CHLOROPHYLL IS VERY GOOD AT ABSORBING _________ LIGHT!
© Pearson Education, Inc. Publishing asPearson Prentice-Hall. All rights reserved.
Absorption of Light by
Chlorophyll a and Chlorophyll b
NEITHER KIND OF CHLOROPHYLL IS VERY GOOD AT ABSORBING _________ LIGHT!
Chlorophyll b
Chlorophyll a
red

29. That’s why leaves LOOK GREEN…..
That’s why leaves LOOK GREEN…..
Chlorophyll doesn’t absorb….
it ___________ GREEN light!

30. That’s why plant have other pigments (like carotenoids)
That’s why plant have other pigments (like carotenoids). They help _________ some wavelengths chlorophyll _______; so the plant can __________ of the sun’s energy.

31. SO WHAT WAVELENGTHS ARE BEST FOR PHOTOSYNTHESIS?
© Pearson Education, Inc. Publishing asPearson Prentice-Hall. All rights reserved.
Absorption of Light by
Chlorophyll a and Chlorophyll b
THE ONES CHLOROPHYLL ABSORBS
THE BEST
________ and
_______________
Chlorophyll b
Chlorophyll a

32. Pearson Education Inc, Pusblishing as Pearson Prentice Hall
Because light is a form of ___________, any molecule that absorbs light also ___________the energy from the light.