Tuesday, May 09, 2006


Plants and animals are complex organisms. They have different kinds of cells. The scientists believe that there are more than 260.000 of plant species. Some plants are very short, they can be hardly seen. However, other plants are bigger than human or animals. In California, there is one of the biggest living plants on the earth that is called sequoia trees. Some stand more than two-hundreds and ninety feet (eighty eight meters) high and measure more than thirty feet (nine meters).

The first fossils were formed during the origin of life. These were the fossil of bacteria. The bacteria consist of single cell. After three and half billion years the first animal evolved. Bacteria used sunlight to manufacture their own food. These cells were prokaryotic meaning that they had no nucleus inside of the cell. Bacteria are still prokaryotic even nowadays. Three billion later the first animals evolved (kohler 2000).

It was earliest known multicellular eukaryotic animal fossil. These involved from “colonies” of single celled organisms. At this moment animals were small and simple (segmented worms, metazoans, coelenterates arthropods) finally evolve into all of the bigger and more multipart animals. At this moment, there was an unexpected “burst” of evolution, often called the Cambrian explosion. As results of explosion different type of invertebrates were involved in the ocean. The animals were consisted with hard shell which formed fossil after the death .These fossils include trilobites and brachiopods. At this moment the Oxygen in the atmosphere attained two percent. The first fish evolved (Kohler 2000).

The ozone layer was formed in the atmosphere due to high percentages of oxygen in the atmosphere. The ozone layer is essential because it blocks ultraviolet rays of the sun. It was nearly impossible for organisms to exist out of water because they would be killed by ultraviolet rays. As a result, it was possible for life form to involve on land. At this time, the ozone was sufficient to permit life on land. The earliest plants evolved. Plants existed on land before animals. The earliest plants were simple. The earliest plants were like the moss of nowadays.

Close to 2.5 billion years ago, the earth surface and atmosphere were stable enough to support primitive life. Single celled organisms started to develop in the seas that covered the planet. The blue algae appeared and across the seas. They used sunlight and water to manufacture their own food, during the process oxygen is created. As the blue-green grew on earth’s seas, they start to fill the atmosphere with oxygen. The oxygen which is produced by blue-green algae is used by other organisms to grow. This organism will produce carbon dioxide carbon dioxide, which algae needed to perform its functions (Kazlev 2000).

Plants are very much essential in the nature cycle. The oxygen that animals breathe comes from plants. Through the process of photosynthesis, plants take energy from the sun, carbon dioxide from the air, water as well as from the soil. As a result, they give off water and oxygen. Animals take part through respiration. The cycle of photosynthesis and respiration play an important role in sustaining the earth’s natural balance of oxygen, carbon dioxide and water.


1. Kazlev.A.M. 2002, PLANT,(land plants) [Internet] 2006 May o8, 11:00.UTC [Cited 2006 May 09, 10:12]. Available from:
2.Kohler S (2000). Plants, [Internet] 2006 May 05, 10:40 UCT [cited 2006 May 09] Available from:
3.McLand, E. (2004). The quite Evolution of Trees. [Online]. Available from: [cited 2006 May 09]

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  • You have not used quotes to indicate copying more than four words verbatim from a reference. This is plagiarism.

    You have also paraphrased paragraphs from a reference without acknowledging it in the text. This is plagiarism.

    By Blogger Gwen, at May 18, 2006 1:56 PM  

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