Answer:
The correct answer is A.
Explanation:
Diffusion is the net movement of a substance from a region of higher concentration to a region of lower concentration. The difference in concentration between two environments creates a concentration gradient which is what drives diffusion. Therefore, this movement does not require aid such as extra energy molecules for active transport or integral membrane proteins for directed movement, hence the answer is not B nor C. If the cell is in equilibrium with its environment, it means that the concentration of substances inside the cell is equal to the concentration outside the cell, and any movement that takes place will be random movement of substances across the plasma memberane. Movement in the cell will not cease as the cell is still active. Therefore, the answer cannot be D either.
<span>he visited galapagos islands</span>
An enzyme lowers the activation energy of a reaction so it can take place within living organism, so an enzyme is a biological catalyst.
Answer:
Middle layer of the meninges that contains the cerebrospinal fluid
