Nicolaus Copernicus was a Renaissance mathematician and astronomer. He was the first to formulate a comprehensive heliocentric cosmology with the Sun, instead of the Earth, as the center of the Universe. The distance of the planets from the sun was in direct relationship to the size of their orbits.
D. Things that are kept constant.
Controls are used in an experiment where some variable is being changed. By only changing one thing and keeping the others constant they can make sure that any change in the results is caused by the variable and not the constant, since the constant didn’t change.
Image result for Compare and contrast intracellular vs. intercellular communication
The key difference between intracellular and intercellular signaling is that intracellular signaling is the communication within the cell while intercellular signaling is the communication between cells. ... Also, within the cell, communication occurs between organelles and nucleus to carry out cellular functions.
Answer:
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Cell divison is necessary to replace cells that are worn and aging. Cells do not have an indefinite life span. Fo example, the life span of a red blood cell is about 120 days.
