During phototropism, the plant hormone auxin<span> controls cell elongation.</span>
Differentiation in plants refers to the processes by which distinct cell types arise from precursor cells and become different from each other. Plants have about a dozen basic cell types that are required for everyday functioning and survival. Additional cell types are required for sexual reproduction. While the basic diversity of plant cell types is low compared to animals, these cells are strikingly different. For example, some cells such as parenchyma cells retain the potential to respond to environmental and/or hormonal signals throughout their life and, under the right conditions, can be transformed into another cell type (transdifferentiation). Other cells such as the water-conducting vessel elements undergo cell death as part of their differentiation pathway and thus can never transdifferentiate to another cell type
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Answer:
The oil produced in United States is light and low sulfur content and they do not have proper processing facilities, hence purchase it from other countries.
Explanation:
About 9.93 million barrels per day U.S purchase oil from 86 countries. Because the crude oil present is not homogeneous in nature. It is very light in nature with low sulfur content or may be high,this particular factor depends upon the method of the refining. Most of the oil are being exported by the Saudi Arabia and then comes Russia followed by Iraq. Despite the collapse in price, U.S. dependence on foreign oil should continue to decrease.
