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Photosynthesis Review Sheet
Define and give an example of:
1. Autotrophs- Any plants, Algae, Cynobacteria… an organism that is able to form nutritional organic
substances from simple inorganic substances such as carbon dioxide.
Heterotrophs- Animals, Humans… An organism that cannot synthesize its own food and is dependent upon
complex organic substances such as plants and other animals for its nutrients.
Here is a diagram of an ATP molecule:
Phosphate groups
How many phosphate groups does ATP have? Three
Describe what happens when ATP gets converted to ADP: Loses a phosphate group
Which is a fully charged battery – ATP or ADP? ATP
Energy in molecules is stored in their: Bonds
The word photosynthesis means: To joint together with light.
Describe what Jan van Helmont discovered with his 5 year experiment
The prevailing theory at the time was that plants grew by eating soil, and van Helmont devised a clever investigation
to test this idea. He weighed a willow tree and weighed dry soil. He planted the tree, watered it and then left it for 5
years. He then re-weighed the tree, which had increased in mass by over 12 stone. He dried the soil and weighed it,
showing that the soil was almost the same mass. He concluded that the tree grew by drinking water.
What did Priestly discover about photosynthesis?
That CO2 is needed and oxygen is produced.
Jan Ingenhousz showed the effects of Priestly’s experiment only happens when the plants are exposed to
LIGHT.
Together the experiments of these scientists led to our basic understanding of photosynthesis Write the
formula for photosynthesis
Pigment- any substance whose presence in the tissues or cells of animals or plants colors them.
Chlorophyll- is a chemical found in the chloroplasts of plants that allows the plant to absorb light. Energy from the
light is used in photosynthesis to make glucose. This contains lots of stored energy which the plant needs to release.
Please write the colors of the 3 accessory pigments:
Carotenoids- red to yellow Anthocyanin- Purple Xanthophyll- Yellow
How does the energy compare of waves in the EM spectrum that have longer vs. shorter wavelengths? The
shorter the wavelength the greater the energy.
How can you remember the colors of the rainbow? Which color has the most energy and the least?
ROYGBIV
most = Violet
Least = Red
Plants appear green to us because they REFLECT green wavelengths and ABSORBS all of the other colors of
wavelengths.
What would be happening to the light if an
object appears yellow? (use your answers
from above to help you)
You can see from the diagram on the right
that Red, Orange, Green, Blue, Purple
Violet are all absorbed and yellow is
reflected back to your eye.
On this chloroplast diagram, label thylakoid, granum, and stroma - also state which part of photosynthesis
they are active in:
Light Dependent Reaction
Light Independent Reaction
Aka: Calvin Cycle
Location
Membrane of the thylakoid
Stroma
Raw Materials
H2O, sunlight and dead batteries
(ADP and NADP+)
CO2 and charged batteries (ATP
and NADPH)
Products
Charged batteries (ATP & NADPH)
(C6H12O6) and dead batteries (ADP
and NADP+)
Light intensity
Amount H2O
Temperature
Surface Area of leaves: same as light intensity
What environmental factor is the cause for leaves to start to change color?
The decrease in sunlight and decrease in temperature.
Why is it that we see reds, yellows, and oranges on the leaves in the fall?
The chlorophyll breaks down, the green color disappears, and the yellow to orange colors become visible and give the
leaves part of their fall splendor. At the same time other chemical changes may occur, which form additional colors
through the development of red anthocyanin pigments.
The Road to Photosynthesis
A. Van Helmont (1600s)
In 1634 Jean Baptist Van Helmont was arrested for the crime of studying plants and other phenomena. He considered
the question "how do plants grow?". The original theory was that plants grew by eating soil.
1. What do you think Van Helmont concluded the increase in weight of the plant ultimately came from?
The increase in weight did not come from dirt as was thpught but came primarily from water.
2. What other factors could be responsible for the increase in the weight of the plant?
We now know that fertilizer, CO2, light and other factors make the plant larger.
B. Joseph Priestly (1770s)
With the new microscopes that were developed in the late 17th century, an Englishman and an Italian discovered
small pores in the leaves of plants, called stomata. The discovery of stomata in the surfaces of leaves suggested that
plants need gases from the air as well as water from the ground. Stomata appeared to allow air to pass to the interior of
the leaves. These pores open if a plant needs to collect carbon dioxide and close if a plant needs to conserve water.
From the discovery of stomata, they speculated that the activities of plants must somehow depend on not only
interactions with water, but also interactions with air. This idea was confirmed through the following experiment by
Joseph Priestly. Examine the picture below and make your own conclusion based on your observations.
1. Why did the candle burn out when the lid was placed on top?
It used up the oxygen and butned out.
2. Why could the candle be relit after giving it time with a mint plant?
Plants produce oxygen which the candel needs to burn.
3. Why does a mouse die when a lid is placed on top?
It runs out of oxygen.
4. Why was the mouse able to survive when placed in the jar with a mint plant?
The mint produces oxygen as a waste project and this si what the mouse needs to breath.
5. What do you think Priestly concluded from this experiment?
That plants provide what mice need and mice provide what plants need.
C. Jon Ingenhousz (1779)
Ingenhousz compared two underwater plants. He placed one plant in a light environment and the other in a dark
environment as seen below.
A. Light Environment
1. Summarize the experiment in your own words.
The plant only produces oxygen in the presence of light not in the dark.
2. What is necessary to produce oxygen?
Light and Carbon Dioxide
B. Dark Environment
Food like glucose
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Electron Carriers (page 209)