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

2. 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?

3. Discussion Questions
Do you think that the factory is a good analogy for the process of photosynthesis in plants?
Why did von Helmont think that plants got their nourishment from soil?
Why did he eliminate soil as a source of nourishment and focus on water?
What did he measure to find out if the willow plant got its nourishment from soil?
What do you think von Helmont concluded when he measured the change in weight of the plant and the soil?

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 2 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. 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.
Carbon dioxide
WATER
Sugars
Oxygen
_____________ + ____________ _______________ + ____________
6 CO2
6 H2O →
C6H12O6
6 O2
_____________ + ____________ _______________ + ____________

9. chlorophyll light energy In addition to water and carbon dioxide,
_______________(green) __
and
__________________
are needed for photosynthesis to happen.
chlorophyll
light energy

10. See a video about PHOTOSYNTHESIS 8B

11. PHOTOSYNTHESIS: Reactants & Products
LIGHT ENERGY
6CO2 + 6H2O
SUGAR + 6O2
So light drives the reaction! Draw Me!!!

12. 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.
ENERGY
ABSORBS

13. colors Visible light is made up of many different
_______________of light
Your eyes “see”
different sizes of
waves as different
___________
wavelengths
colors

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

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

16. absorbs ALL except BLUE reflected
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
BLUE
reflected

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

18. absorbs ALL ENERGY 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.
absorbs ALL
ENERGY

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

20. Which wavelengths of light are these Flowers REFLECTING?
Purple & yellow
yellow
Images by: VanderWal

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

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

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

24. GREEN leaves have BOTH chlorophyll AND carotenoids __________________
but the huge amount of chlorophyll ______
the other colors and
leaves usually
look green
ALL THE TIME
hides

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

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

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

28. CFU!!! 1. Where do plants get the energy they need to grow?
2. What ingredients (raw materials) do green plants need for photosynthesis?
3. Where do plants get these ingredients?
4. In what part of the plant does photosynthesis take place?
5. What do plants use the sun’s energy to manufacture?
6. What do they use the energy stored in glucose for?
7. What gas do animals exhale and plants take in? What do plants use this gas for?
8. What gas do plants give off and animals inhale?
10. Why are plants called producers?
11. Green plants make their own food from 1) __________ that is absorbed by the roots and travels up the stem to the leaves; 2) a gas in the air, called __________; and 3) energy from __________, which the green leaves trap.

29. THE BIG PICTURE
Very important to remember what goes into a plant and then what comes out. Also known as the reactancts (going in) and the products (coming out) Put many stars next to this in your notes
Carbon dioxide
WATER
Sugars
Oxygen
_____________ + ____________ _______________ + ____________
6 CO2
6 H2O →
C6H12O6
6 O2
_____________ + ____________ _______________ + ____________

30. Remember from CELL BIO CHLOROPLASTS
Enzymes for PHOTOSYNTHESIS are in the ________________
CHLOROPLASTS

31. PHOTOSYNTHESIS HAPPENS IN CHLOROPLASTS
THYLAKOIDS
= sac-like
photosynthetic
membranes
inside chloroplast
Image from BIOLOGY by Miller and Levine; Prentice Hall Publishing©2006

32. Factors that Affect Photosynthesis
AMOUNT OF WATER
____________________
Water is one of the raw materials needed, so
A shortage of water can ________________
photosynthesis
slow or stop
Desert plants and conifers
that live in dry conditions
have a waxy coating on
their leaves to prevent
water loss.

33. Factors that Affect Photosynthesis
TEMPERATURE
Photosynthesis enzymes function best between 0° C - 35° C
At temperatures above or below this range, photosynthesis will slow or stop
Conifers in winter may carry out
photosynthesis only occasionally

34. Factors that Affect Photosynthesis
LIGHT INTENSITY
____________________
More light increases rate of photosynthesis
up to a certain level until plant reaches its
maximum rate of photosynthesis

35. THE BIG PICTURE sugars PHOTOSYNTHESIS provides
the _____________ we breathe
and the __________heterotrophs consume to survive
OXYGEN
sugars
Carbon dioxide
Sugars
WATER
Oxygen
_____________ + ____________ _______________ + ____________

36. Check For Understanding
Write the equation for Photosynthesis.
Increasing the intensity of light will _______ Photosynthesis.
The name of the organelle that allows plants to do photosynthesis is _________.
Decreasing the amount of water will _________ Photosynthesis.
Plants in Alaska where its colder will do (more or less) photosynthesis than plants in Florida?

37. Core High School Life Science Performance Descriptors
High school students performing at the
ADVANCED level:
explain the steps of photophosphorylation and the Calvin Cycle;
analyze chemical reaction and chemical processes involved in the Calvin Cycle and Krebs Cycle;
predict the function of a given structure;
predict how homeostasis is maintained within living systems
PROFICIENT level:
describe and give examples of chemical reactions required to sustain life (hydrolysis, dehydration synthesis, photosynthesis, cellular respiration, ADP/ATP, role of enzymes);
describe the relationship between structure and function
explain how homeostasis is maintained within living systems;
predict how life systems respond to changes in the environment;
BASIC level
name chemical reactions required to sustain life (hydrolysis, dehydration synthesis, photosynthesis, cellular respiration, ADP/ATP, role of enzymes);
recognize that different structures perform different functions;
define homeostasis;