Work with a partner
Read Section page 60 in Section 2.4, and discuss answers
to questions C­F.
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Discuss your responses with the class.
Any Questions?
Title: Jun 7­8:32 AM (1 of 25)
Title: Oct 16­10:13 AM (2 of 25)
Work with a partner
Read the section on Priestly's second experiment on page 61, and discuss answers to questions G­I with your partner.
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Discuss your responses with the class.
Any Questions?
Title: Jun 7­8:32 AM (3 of 25)
Title: Oct 17­10:45 AM (4 of 25)
Work with a partner
Read the rest of page 61, and discuss answers to questions J and K with your partner.
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Discuss your responses with the class.
Any Questions?
Title: Jun 7­8:32 AM (5 of 25)
Title: Oct 17­11:05 AM (6 of 25)
Title: Oct 17­11:19 AM (7 of 25)
Work with a partner
If plants undergo both photosynthesis (which uses CO2 and releases O2) and cell respiration (which uses O2 and releases CO2), why do we say that plants remove CO 2 from the atmosphere and produce O 2?
Title: Jun 7­8:32 AM (8 of 25)
Carbon Cycle
Why do nutrients need to be recycled within the ecosystem?
Why is carbon important for living things?
Title: Jun 6­10:52 AM (9 of 25)
Carbon Cycle
The Carbon Cycle consists mainly of two processes, Photosynthesis and Cell Respiration
What organisms perform photosynthesis?
What ones perform cell respiration?
Title: Jun 6­10:52 AM (10 of 25)
Carbon Cycle
What is the pigment that plants use to capture sunlight?
Chlorophyl
...This is what gives plants their green color.
Pigments such as chlorophyll are made of proteins.
Title: Jun 6­10:52 AM (11 of 25)
Chemical Equations of the Carbon Cycle
Photosynthesis:
Cell Respiration:
Title: Jun 6­10:54 AM (12 of 25)
The two processes linked together form the carbon cycle.
Plants capture carbon in the form of carbon dioxide from the atmosphere, and use energy from sunlight to combine it with water and form sugar (glucose). When they do this, oxygen is released into the atmosphere.
When animals eat plants, they break down the glucose by combining it with oxygen to release the stored energy, which their cells use. The products of this are carbon dioxide and water, which the animals give off.*
*(Plants also use this process to release the energy stored in the glucose they manufacture.)
Title: Jun 6­10:56 AM (13 of 25)
Carbon Cycle
Title: Jun 7­8:37 AM (14 of 25)
Homework
Read Section 2.4 (pages 62­65) and complete questions #1­6 and 8 on page 65.
Title: Jun 7­8:57 AM (15 of 25)
Nitrogen Cycle
Nitrogen is an important nutrient in all living things. It is used in making proteins and DNA (genetic material)
Knowing what nitrogen is used for, how does this explain why plants that grow in nitrogen­poor soil turn yellowish?
Title: Jun 7­8:57 AM (16 of 25)
Nitrogen Cycle
How much of the atmosphere is composed of nitrogen?
The atmosphere is about 79% nitrogen...but organisms cannot absorb pure nitrogen and make use of it directly.
In order to be used, the nitrogen has to be combined with oxygen to form the nitrate ion...
NO31­
Title: Jun 7­8:57 AM (17 of 25)
Nitrogen Cycle
There are two main ways in which nitrogen in the atmosphere can be converted into nitrates.
1) Bacteria in the soil, called nitrogen fixing bacteria, are able to combine atmospheric nitrogen and oxygen to
form nitrates.
2) The energy released during a lightning strike causes
nitrogen and oxygen to combine into nitrate ions, which
are then washed into the soil with rain. (This only
accounts for a small amount of nitrates though)
Title: Jun 7­8:57 AM (18 of 25)
Nitrogen Cycle
Nitrogen fixing bacteria survive well in soil which is well aerated (in other words, loose enough to allow plenty of oxygen to penetrate)
They also live in bumps, called nodules, on the roots of some types of plants (such as clover and alfalfa). These bacteria form far more nitrate than they can use...the excess is released into the soil, where it can be absorbed and used by other plants.
Title: Jun 7­8:57 AM (19 of 25)
Nodules on the roots of a clover plant.
Title: Jun 6­11:07 AM (20 of 25)
Title: Jun 6­11:24 AM (21 of 25)
Nitrogen Cycle
Title: Jun 7­8:37 AM (22 of 25)
Phosphorous Cycle
Phosphorous in living organisms is used in the form of phosphate ions.
PO43­
It is used in making DNA, in the calcium phosphate used by animals to form bones and shells, and in molecules which form cell membranes and help release chemical energy.
Title: Jun 7­8:57 AM (23 of 25)
Phosphorous Cycle
Phosphates follow a short cycle and a long cycle.
The long cycle involves phosphates being deposited by decomposition on the ocean floor, accumulating in sediment to form rock, and then being raised over periods of millions of years to form new landmasses. Eventually, weathering washes the phosphates out of the rock and back into the soil, where they can be taken in and used by plants.
In the short cycle, phosphates are absorbed by plants from the soil, travel through the food chain, and are returned to the soil by decomposition.
Title: Jun 7­8:57 AM (24 of 25)
Phosphorous Cycle
(short cycle only)
Title: Jun 7­8:37 AM (25 of 25)