 In your notebooks, take 2 minutes to try to come up with your own definition of what a cycle is.
 Work with your lab/table partners to come up with a complete and scientific definition of a cycle.
 Let’s share out!

Definitions of Cycle
 Biological Definition :
 A repeating series of events or processes in plants and/or animals
 Physical/Chemical Definition:

A continuous change or chain of changes in the state of a system that leads to a return of the system to its original state.

Understanding Earth’s Cycles

Earth’s Cycles
Types of Cycles

Carbon Cycle
 Water Cycle
 Nitrogen Cycle
Phosphorus Cycle these cycles and locations during this unit.
Areas of Cycling on Earth
 Atmosphere – Air
 Biosphere – Living things
 Geosphere – Land
 Hydrosphere – Water
 Cryosphere – Ice and
Glaciers

 The Carbon Cycle :
 The process by which carbon is cycled between the atmosphere(air), geosphere (land), hydrosphere(water) and biosphere(living things).
 Why does Carbon matter?

Carbon is a building block of proteins, fats and carbohydrates
 This is our FOOD!
 CO
2
(Carbon Dioxide) is a greenhouse gas
 Too little and our planet gets cold
 Too much and our planet gets hot

The Carbon Cycle Variations
 Short-Term Cycle
 This is a daily cycle

Involves the following spheres
 Atmosphere
 Biosphere

Hydrosphere
 Long-Term Cycle
 This is a drawn-out or protracted cycle (taking hundreds and millions of years)
 Involves the following spheres
 Atmosphere
 Biosphere

Geosphere
 Hydrosphere

The Short-Term Cycle
 The pathway of this cycle is:
 Atmosphere  Biosphere  Atmosphere
 The Hydrosphere (mostly the oceans) acts like a
Carbon Dioxide “Warehouse”
 CO
2 can be “Stored” and “Released” as needed when there are temporary imbalances.
 When these imbalances go too long we get other problems but we will talk about that later.

How can Carbon move from the
Atmosphere to the Biosphere?

Plants!
Without Plants and photosynthesis we would not be able to access the Carbon in the atmosphere.
 Photosynthesis  Conversion of Carbon Dioxide (CO
2 into sugars and carbohydrates.
)

Carbon Dioxide + Water + Sunlight  Sugar + Oxygen

How does Carbon move back to the
Atmosphere from the Biosphere?
Cellular Respiration!
 This is done by both animals and plants
 It breaks down the sugar created in photosynthesis to give living things energy! (sun energy to chemical energy )
 Cellular Respiration  The conversion of sugar into usable energy
Sugar + Oxygen  Carbon Dioxide + Water + Energy

The Carbon Cycle – Recap
The combination of photosynthesis and cellular respiration allows Carbon to move continuously from the Atmosphere to the Biosphere and then back to the Atmosphere.

Changes in one sphere can lead to changes in another spheres.
For example
If we loose a large number of plants, less carbon dioxide will be removed from the atmosphere and converted to sugar, animals will continue to release carbon dioxide as a waste product and it will build up in the atmosphere.
Based on what you learned about Carbon Dioxide in previous units, what impact could that have on the environment?