Explanation:
Divide the number of cells in view with the diameter of the field of view to figure the estimated length of the cell. If the number of cells is 50 and the diameter you are observing is 5 millimeters in length, then one cell is 0.1 millimeter long. Measured in microns, the cell would be 1,000 microns in length.
Matter is anything that takes up space. Your mass determines how big, or small you are. Or, how big or small something is. Matter is in everything. Even air has matter. Humans are made of matter. Matter makes up atoms, carbon, cells, and everything else you can think of. (Except ideas)
Answer:
An index fossil is a fossil used to determine the age of the sediments in which it is found. When quickly approximating the age of new finds, an archaeologist looks at the rocks in which it is buried, as those sediments would have been on the surface at the time of the death of the pre-historic creature.
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What is different with retroviruses in reproduction is that they do not kill their hosts at first because they can still insert their own genome. This process is what is known the reverse transcription. This is done by different proteins.