<span>A fossil leaf that is made only of carbon preserved between two rock layers is called carbon film fossil.
</span>Characteristic of the carbon film fossils is that they are primarily composed of carbon. The fossil leaf has usually lost <span>internal components (cell walls and internal cell structures ).</span>
<span>Anton van Leeuwenhoek learned to grind lenses ( 1668) and develop simple microscopes.
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Leeuwenhoek heated the middle of a small soda glass rod , over a flame. On pulling apart the two ends, the glass rod elongated into thin whiskers .
Heating the end of this whisker resulted in a tiny high quality glass sphere. These glass spheres then became the lens of his microscope, with the smallest sphere providing the greatest magnification.
Leeuwenhoek's designs were very basic. The body of the microscope was a single lens mounted in a tiny hole on a brass plate. The specimen was then mounted on a sharp point that sticks up in front of the lens. It's position and focus could be adjusted by turning the two screws.
The entire instrument was about 3 to 4 inches long and had to be held up close to the eye, requiring good lighting and great patience to use.
Since you did not give a list of choices,here are some reasons why l<span>iving cells cannot use heat to provide the activation energy for biochemical reactions:
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>Heat can never be used to do work.
>Heat is not readily available to all living cells.
>Heat doesn't provide the activation energy for their reactions.
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