UNIT 1: Living Organisms in the Environment



Diversity of Life

Living things have the ability to maintain themselves and reproduce. Anything from the lowliest, single-cell bacterium to the most complex vertebrates and towering redwood trees have that ability. Viruses, on the other hand are only quasi living. They are not much more than bundles of DNA. To survive, they force host cells to carry out these functions for them.

There are millions of species of organisms living on the Earth today. Many millions of others that lived in the past are now extinct. Scientists and natural philosophers (such as Aristotle in ancient Greece) have recognized that organisms can be organized according to similarities and differences.






This topic  is designed as an introduction. This section involves the study of the interrelationships between organisms and their environment and to appreciate the variety and complexity of these relationships.




Characteristics of Living Organisms

  • Respiration- living things require energy for several life processes such as metabolism and locomotion. 
        
  • Feeding- nutrients are required by all living things to obtain energy and build new protoplasm.


  • Excretion- this is the process of removing metabolic waste product from living things.


  • Growth-growth in living things is the increase in size and number of cells.


  • Movement- all living things are able to move on their own accord.


  • Reproduction- all living things can produce new individuals.


  • Irritability- the ability of a living thing to respond to changes in the environment. 




For more information on  characteristics of living organisms
please click the link below:
http://www.xtremepapers.com/revision/gcse/biology/characteristics_of_living_organisms.php





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