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.
<span>After immunizations, the weakened vaccine viruses or bacteria replicate (grow) in the vaccinated person. This means a relatively small dose of virus or bacteria can be given in order to stimulate an immune response.</span>
