Identical twins could not be considered as clones for they are different individuals which came from the same egg and sperm. Clones are produced asexually, a copy of another organism. Even though identical twins share the same DNA, they have different qualities as of the other twin which makes them their own unique self.
The movement in phloem is bidirectional, whereas, in xylem cells, it is unidirectional (upward).
30% of the earth's surface is covered by forests.
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We breathe in air, not straight oxygen. Attached is a pie chart showing roughly what percentage of what is in the air we breathe
