This picture is an example of early autrophs.
Click on image for full size
Image courtesy of Corel Photography
Over a very long time, gradual changes in the earliest cells gave rise to new life forms. These new cells were very different from earlier cells because they were able to get their energy from a different source -- the Sun.
Organisms that are able to make their own food by using the energy of the
Sun are called autotrophs. Photosynthesis is the name of the process by which these autotrophs eat.
Because the autotrophic bacteria were able to feed themselves by
using the energy of the Sun, they were no longer dependent on the same
limited food supply as the earliest life and were able to grow and multiply. Over millions of years of
evolution, these sun loving bacteria eventually led to modern day plants.
The appearance of organisms capable of photosynthesis was very significant -- if it weren't for the photosynthetic activity of
these early bacteria, Earth's air would still be without oxygen
and animals which need oxygen, including humans, could never have even begun!
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