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Early Life - Windows to the Universe

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Become a nitrogen atom in the nitrogen cycle in our Traveling Nitrogen Classroom Activity Kit/Game. See all our games, activity kits and classroom activities.
This picture is an example of early autotrophs.
Click on image for full size
Image courtesy of Corel Photography

Early Life

Over a very long time, gradual changes in the earliest cells gave rise to new life forms. These new cells were very different from the earlier heterotrophs because they were able to get their energy from a new source -- the Sun.

Organisms that are able to make their own food (in the form of sugars) by using the energy of the Sun are called autotrophs, meaning "self-feeders". Photosynthesis is the name of the process by which these autotrophs use energy from the sun and 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 their ancestors and were able to flourish. Over millions of years of evolution, photosynthetic bacteria eventually gave rise to modern day plants.

The appearance of organisms capable of performing photosynthesis was very significant -- if it weren't for the photosynthetic activity of these early bacteria, Earth's atmosphere would still be without oxygen and the appearance of oxygen-dependent animals, including humans, would never have occurred!

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Traveling Nitrogen is a fun group game appropriate for the classroom. Players follow nitrogen atoms through living and nonliving parts of the nitrogen cycle. For grades 5-9.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF