lunes, 12 de octubre de 2015
miércoles, 7 de octubre de 2015
sábado, 3 de octubre de 2015
VIRUSES
Viruses are smaller than any known living being. We have only been able to study them since the invention of the powerful electronic microscope.
Under examination, we can see that they are made up of diverse types of geometrical capsules and genetic material, which contain the information necessary to reproduce.
Viruses can not perform vital functions on their own. They must introduce themselves into living organisms; in other words, infect them in order to survive.
For this reason, viruses are the cvause of many illnesses, such as the flu, measles, polio or hepatitis.
Some types of lichens only grow in places where there is little or no contamination. By simply observing what types of lichen grow in an area scientists can determine the level of contamination and the air quality of an area.
Lichens do not grow in places where there are high levels of contamination. Only onw or two types of lichen grow in places where there are medium levels of contamination. A large variety of lichens grow in places where there are low levels of contamination.
jueves, 1 de octubre de 2015
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