Scientists believe that nearly 2.5 billion years ago after the big bang some 13 to 14 billion years ago the surface of the earth and the evolution of the atmosphere became stable in order to support the early life. Therefore, organisms with a single cell started to develop in the sea which covers the planet, earth. It is also said that the sea has been formed by the accumulation of water vapour and carbon dioxide yielded by the volcanic eruptions. The first evolution of plant started with a single cell organism known as the blue green algae. On the other side the first animal to evolve is thought to be from a multi cellular organism. In other words this means that according to the scientists life has began in the sea.
When the blue green algae started to grow in the seas of the earth, they produce oxygen which then spread through around the atmosphere we know today. The availability of oxygen in our atmosphere made it easier for the other organisms to develop on the earth. That is why plants are called producers, because they are the once that brought life on the earth by being able to produce their own food during the process of photosynthesis.
During the process of photosynthesis, the blue-green algae use energy from the sunlight, carbon dioxide from the atmosphere, water and mineral from the soil. At the same time when they photosynthesize, they release oxygen and water which are useful for life of other organisms on the earth. Animals and other organisms use the produced oxygen and release carbon dioxide which is also used by plants during the process of photosynthesis.
The first animal to evolve is thought to be eukaryotic animal. The information has been found by studying the fossils of multi-cellular eukaryotic animal. It is further explained by saying that the multi-cellular organisms underwent evolution from a single cell organism. Even though the first animals were very small, but they did manage to evolve into all other large and complex animals that we see on the earth today. The first animal were called eukaryotic because they possess nucleus in their cells as opposed to prokaryotic animals which they do not possess nucleus in their cells. These first animals are called consumers, because they depend on plants for their food. Therefore animals depend on plants for their food.
In conclusion, plants especially the blue green algae are thought to be the first plants to evolve on earth. They are also termed producers because they use energy from the sun, carbon dioxide and water to produce their own food during the process of photosynthesis. On the other side the first animal to evolve is thought to have evolved from a multi-cellular eukaryotic animal in the colonies of a single cell organism. Therefore animals and other organisms depend on plants for food because they are incapable of manufacturing their own food. Plants are also first in the food chain because they have the ability to manufacture their own food.
Wikipedia contributors. Segmentation [Internet]. Wikipedia, The Free Encyclopaedia; 2006 March 24, 13:04 UTC [cited 2006 May 08]. Available from: http://en.wikipedia.org/wiki/Segmentation_(biology)
Wikipedia contributors. Evolution [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 08, 06: 45 UTC [cited 2006 May 08]. Available from: http://en.wikipedia.org/wiki/Evolution
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