Concept 8.4

Summary:
- Some of the processes that occur on a global scale on Earth depend on the metabolism of tiny chloroplasts and mitochondria.
- Through photosynthesis, producers such as grass convert inorganic carbon dioxide to organic compounds.
- Consumers such as a Cape buffalo obtain the organic compunds by eating the producers.
- Cellular respirtation by producers and consumers returns carbon dioxide to the atmosphere.
- No other chemical process on the planet matches the output of photosynthesis.
- Earth's plants and other photosynthetic organisms make about 160 billion metric tons of organic meterial per year.
- A key elemement of the carbon cycle is carbon dioxide.
- Plants use carbon dioxide to make sugars in phtosynthesis, and most organisms give off carbon dioxide as waste from cellular respiration.
- Though any one organism may use or produce relatively small amounts of carbon dioxide, the total effect of all the organisms on Earth has a very large effect on the amount of carbon dioxide in the atmosphere.
- Carbon dioxide in the atmosphere also traps heat from the sun that would otherwise escape from Earth back into space.
- Greenhouse effect keeps the world climate warm enough for living things.

Concept check:
1. Give an example of carbon moving from an inorganic compound to an organic compound to an organic compund in the carbon cycle. Give an example of carbon moving from an organic to an inorganic compound.
Carbon cycle, photosynthesis

2. How is carbon dioxide important to Earth's climate?
The total effect of all the organisms on Earth has a very large effect on the amount or carbon dioxide in the atmosphere.

Vocab:
Carbon cycle: the process by which carbon moves from inorganic to organic compounds and back.
Greenhouse effect: the property that keeps the world climate warm enough for living things.