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Answer:
The effect of an external physical factor on cell division is clearly seen in density-dependent inhibition, a phenomenon in which crowded cells stop dividing. ... When cells have formed a complete single layer, they stop dividing (density-dependent inhibition).
Explanation:
Answer: The oxygen content at the source of the streams or rivers is higher as compared to the mouth of the river. Consequently, the organisms which require more oxygen tend to find at the source of the rivers whereas the organisms which require less oxygen tend to find at the mouth of the river.
Explanation:
