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Re: closed ecosystem

Olga writes:

<snip>< complete
> >sealed inside a glass sphere. 
> Am I wrong in thinking that this would be impossible. Surely the sphere
> could not be completely enclosed. The living things would need air.  >>

Not exactly air.  The animals need oxygen, which it exchanges for CO2.  The
plants utilize CO2 during photosynthesis, exchanging it for O2.  The two types
of organisms establish a balance based on each other's metabolism, the
elements contained in the ecosystem, and the amount of energy provided via
sunlight, which is converted to metabolic energy by the photosynthesis.  The
plants recycle the animal waste, and the animals recycle the products of the
plants' metabolism.

Earth is essentially a closed ecosystem, with the only thing being imported to
support it is the sunlight.  The water, nitrogen, oxygen, carbon dioxide, and
all the other things are constantly recycled back and forth into various
compounds by the metabolism of the organisms that live here.

Bob Dixon