<span>The specimen are placed in vacuum while examining the cells or living organisms. Also, the electron must penetrate inside of the cell and in such conditions, any living organism is not able to survive. Thus, this reason best explains the answer to why dead cells specimen must be used for Transmission electron microscopy.</span>
1. Griffith in his experiment used two related strains of bacteria (Streptococcus pneumonia), known as R and S and mice, trying to develop a vaccine against pneumonia. R strain-formed nonvirulent, rough-edged colonies
S strain- rounded and smooth colonies, with sugar protection coat, virulent
Mice that were injected with S strain developed pneumonia and died.
But, when mice were injected with heat-killed S strain it did not cause disease in mice.
The next part of experiment is the injection of combined harmless R bacteria with harmless heat-killed S bacteria. The result was that the mouse developed pnenumonia and in blood sample from the dead mouse, living S bacteria were found.
2. From his experiment, Griffith concluded that injected together, R strain and S strain bacteria most likely “communicate”. The R-strain bacteria took "transforming principle" (we know today that this is genetic material DNA) from the heat-killed S bacteria which allowed them to "transform" into virulent bacteria.
1)Biotic factors are the living components of an ecosystem. These include living animals, plants, and microscopic organisms like bacteria.
Abiotic factors are the non-living components of an ecosystem. ... Biotic and abiotic factors both influence each other.
