Answer:
The answer is A
By the late 1830s, botanist Matthias Schleiden and zoologist Theodor Schwann were studying tissues and proposed the unified cell theory. The unified cell theory states that: all living things are composed of one or more cells; the cell is the basic unit of life; and new cells arise from existing cells.
Carrier and channel proteins in the plasma membrane
are similar because they are both transport membrane proteins that allow
molecules to flow in and out of the membrane. Meanwhile, carrier protein can
further be classify as active or passive transport. These two transport
proteins makes cell’s ability to perform their functions well by maintaining a
difference between the intracellular and extracellular environment.
This is obvious but the correct answer is B. Earth
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