Pioneer organisms are the first organisms that reoccupy a region that was destroyed by a disaster like flood, forest fire, volcanic eruptions, etc. These pioneer species can grow in the habitat that is barren and is not suitable for the growth and survival of other species.
Some of the pioneer species are lichens and algae. Pioneer species like lichens help in the formation of soil from breakdown or rocks which allow the formation of a suitable environment for the ecological succession of other species like mosses, algae, and other small plants. Therefore the statement is true.
Enzyme activity is highest at 6.6. This means that 6.6 is the optimal pH for this enzyme. If the pH is too low or high the enzyme will denature and the enzyme activity will lower.
The solution is hypertonic because the amount of solute(s) is higher outside of the cell than it is inside the cell, so the solvent (e.g. water) would move from the cell to the solution in order to obtain equilibrium between the two.
