08 Photosynthesis Fifth standard characters

Photosynthesis
5 th grade

1. Photosynthesis

2. All we know in science began with a question….
In 1634, Jan Baptist van Helmont had a question:
Where do plants get their mass when they grow?



Video:
where do
plants get
their mass?

Pause at
0.45

3. Three Hypotheses:
A.Plants get their mass from water.
B.Plants get their mass from soil.
C.Plants get their mass from air.
Choose the ONE you think is the
accurate answer and write it in your
notebook. We will refer back to this
question periodically.

4. Scientists then design an
experiment for testing the
hypothesis.
Jan Helmont wanted to test the
idea that plants gained mass
from consuming soil in some
way. Think of a way you could
test this idea and be prepared to
share it with the class.

5. Helmont’s Experiment
1. Measure the mass
of soil placed in a pot

2. Measure the mass
of a young willow
plant.

6. 3. Plant was watered and
placed in sunlight.
4. 5 years later, the mass of the soil and
the mass of the willow was determined.

7. Important Data - Helmont Experiment
Based on the data, was his hypothesis that
plants consumed soil accurate?
Where did the mass of the plant come from?



Mass at Start Mass After 5 Years
Soil 90 kg 89.9 kg
Plant 2.25 kg 76.1 kg

8. A.Plants get their mass from water.
B.Plants get their mass from soil.
C.Plants get their mass from air.
Which hypothesis did Helmont eliminate?
If “B” was your hypothesis, choose either A or C as a
new hypothesis and write this in your notebook. With
the person sitting next to you, develop an experiment
to test your new hypothesis (either A or C). Create a
sketch of your design and be prepared to share it with
the class. ~ 5 -10 minutes.

9. Though we don’t have time to look at all of the historical
experiments, scientists finally realized that air and
water were necessary for plants to grow in mass.
The Law of Conservation of Matter - matter cannot
be created or destroyed it just changes forms.

10. The Law of Conservation of Energy
Energy ...
-cannot be created or
destroyed, it can change
form.
-can be transferred from
one form to another.
SOLAR → CHEMICAL

11. Energy
All living things need energy to survive
Autotrophs (plants) make food from the sun
Heterotrophs (animals) consume food

12. Pause and Reflect
1. What do plants need to grow in mass?
a) light b) water c) air d) soil
2. How did Helmont show that soil did not contribute to the mass of the plant?
a) weighed the soil b) watched the plant grow c) measured water
3. Energy from the sun is converted to chemical energy such as that stored in:
a) soil b) apples c) air
4. Why was the law of conservation of matter important to Helmont’s experiment?

13. Priestley’s Experiment:

1) Caption the images 2) Summarize the Results

14. How is energy from the sun converted to chemical energy?
Photosynthesis is the
process in which plants
1) use energy (sunlight)
2) to convert water and
carbon dioxide
3) into glucose and oxygen.

O
2
Glucose

15. The Photosynthesis Equation
6CO
2
+ 6H
2
O → C
6
H
12
O
6
+ 6O
2

carbon dioxide + water → sugar + oxygen

16. Leaf Anatomy


Stoma (stomata)
are openings on
the leaf where
gases are
exchanged.
See also: leaf
anatomy coloring

18. Photosynthesis Graphic
Sunlight
Glucose
Oxygen
Carbon Dioxide
Water

19. Photosynthesis Graphic
Sunlight
Glucose
Oxygen
Carbon Dioxide
Water

20. Chloroplasts - where photosynthesis occurs
CHLOROPHYLL (pigment)
absorbs most colors of light
except for green.

21. Chloroplasts
Stacks of thylakoids | Stroma = space between
Draw this
chloroplast
and label it in
your notes.

22. Let’s watch this TED Video to review.

23. Stages of Photosynthesis
Stage 1: Light
Dependent
Light + Water
Releases
Oxygen
(Thylakoid)




Stage 2
Light-Independent
CO
2
in

Glucose out

(Stroma)
“How Does
Photosynthesis
Work” Handout

24. H
2
O
CO
2
O
2
Sunlight

Glucose

ATP

NADPH

Light Reaction
Thylakoids

Calvin
Cycle
Stroma

Student Handout

25. H
2
O CO
2
O
2
Sunlight

Glucose

ATP

NADPH

Thylakoids

Calvin
Cycle
Stroma

Light Reaction

26. What Goes
IN
What comes
OUT
Where it
Occurs
Light
Dependent





Light
Independent
(Calvin Cycle)

27. ATP - an energy carrying molecule
( Adenosine Triphosphate )
-produced by the mitochondria
- requires glucose & oxygen
- breaking bonds releases energy

28. How Can the Rate of Photosynthesis Be Measured?
Examine the diagram, try
to explain what you see
with regard to plants and
photosynthesis.
1. Will the water level in the
tube go up or down?

2. What will happen if you turn
off the light?

3. Where is the plant getting
carbon dioxide from?
See Virtual
Simulation as a
demonstration
lab

30. What factors could affect the rate of photosynthesis?
Interpret these graphs….

31. Absorption Spectrum of Chlorophyll A
What is this graph
showing about light
colors that plants
absorb?
See Virtual Simulation
as a demonstration
lab

32. Why do leaves turn red and yellow in the fall?
Carotenoids!