1 1 Photosynthesis Photosynthesis converts light energy into chemical energy Plants and some other types of organisms (all of which are autotrophes) are able to use light energy from the sun to produce food 2 Saving for a Rainy Day Suppose you earned extra money by having a part-time job. At first, you might be tempted to spend all of the money, but then you decide to open a bank account. 1. What are the benefits of having a bank account? 2. What do you have to do if you need some of this money? 3. What might your body do when it has more energy than it needs to carry out its activities? 4. What does your body do when it needs energy? Section 8-1 Interest Grabber 3 8 – 1 Energy and Life A. Autotrophs and Heterotrophs Section 8-1 Section Outline 4 Autotrophes • These form the base of all ecosystems • Use energy from the sun to produce C 6 H 12 O 6 (sugar/food) from CO 2 + H 2 O (carbon dioxide + water) – These are called photoautotrophes (>99% of all producers) • Some use the energy stored in the chemical bonds of inorganic molecules – These are called chemoautotrophes (< 1% of all producers)
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Section 8-1 Photosynthesis - Jones-Biofull... · Section 8-2 Photosynthesis: Reactants and Products 23 Absorption of Light by Chlorophyll a and Chlorophyll b V B G YO R Chlorophyll
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1
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syn
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Photosynthesis converts light energyinto chemical energy
Plants and some other
types of organisms (all of
which are autotrophes) are
able to use light energy
from the sun to produce
food2
Saving for a Rainy Day
Suppose you earned extra money by having a part-time job. At first, you might be tempted to spend all of the money, but then you decide to open a bank account.
1. What are the benefits of having a bank account?
2. What do you have to do if you need some of this money?
3. What might your body do when it has more energy than it needs to carry out its activities?
1. A solar-powered calculator uses solar cells that are found in rows
along the top of the calculator. Into what kind of energy is the light
energy converted so that the calculator works?
2. Recall that plants use light energy from the sun to make food. Into
what kind of energy is the light energy converted by plants?
3. Most plants, no matter what size or shape they are, have some parts
that are green. Which parts of a plant are usually green?
4. What does the green color have to do with the plant’s ability to
convert light energy into the energy found in the food it makes?
Section 8-2
Interest Grabber continued
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8–2 Photosynthesis: An Overview
A. Investigating Photosynthesis
1. Van Helmont’s Experiment
2. Priestley’s Experiment
3. Jan Ingenhousz
Section 8-2
Section Outline
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Van Helmont’s Experiment
•In the 1600s, the Belgian physician Jan van Helmont devised
an experiment to find out if plants grew by taking material out
of the soil.
– determined the mass of a pot of dry soil and a small
seedling
– He watered it regularly. At the end of five years, the
seedling, which by then had grown into a small tree, had
gained about 75 kg
– The mass of the soil, however, was almost unchanged.
– Conclusion? That most of the gain in mass had come
from water, because that was the only thing that he had
added.
– (the carbon for carbohydrates comes from the CO2 in the
atmosphere)
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Priestley’s Experiment
• 1771- Priestley took a candle, placed a glass jar over it, and
watched as the flame gradually died out.
– Something in the air, Priestley reasoned, was necessary
to keep a candle flame burning.
– When that substance was used up, the candle went out.
– That substance was oxygen.
•Priestley then found that if he placed a live sprig of mint under
the jar and allowed a few days to pass,
– the candle could be re-lighted and would remain lighted
for a while.
– The mint plant had produced the substance required for
burning.
– In other words, the mint released oxygen.
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Jan Ingenhousz’s Experiment
•1779 - Dutch scientist Ingenhousz
showed that the effect observed by
Priestley occurred only when the plant
was exposed to light.
–The results of both Priestley's and
Ingenhousz's experiments showed
that light is necessary for plants to
produce oxygen. 20
8–2 Photosynthesis: An Overview
A. Investigating Photosynthesis
1. Van Helmont’s Experiment
2. Priestley’s Experiment
3. Jan Ingenhousz
B. The Photosynthesis Equation
C. Light and Pigments
Section 8-2
Section Outline
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What is the basic equation for
photosynthesis?
6H2O + 6CO2 C6H12O6+ 6O2Water plus carbon dioxide plus light yield sugar and oxygen
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Light Energy
Chloroplast
CO2 + H2O Sugars + O2
Section 8-2
Photosynthesis: Reactants and Products
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Absorption of Light byChlorophyll a and Chlorophyll b
V B G YO R
Chlorophyll b
Chlorophyll a
Section 8-2
Figure 8-5 Chlorophyll Light Absorption
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B
A
This is the visible spectrum
of light (what we can see)
(One billionth (10-9) of a meter)
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A Look Into the Future
It is 100 years in the future and you are a research scientist. An enormous volcanic eruption has recently sent huge quantities of dust and ash into the atmosphere.
In your notes, make a list of how this event will affect each of the following: