Regeneration in planarians depends on the presence of stem cells called neoblasts. These cells are distributed throughout the body and, when part of the worm has been amputated, they are activated to reform the tissues that have been removed.
<span>Sumerians built walls using the natural resource they were surrounded with, which was namely clay. They used this clay to create fired mud-bricks, as there was not any other building stone available at the time. However, the clay mud-bricks proved to be a solid structure for town fortification.</span>
Assuming this is multiple choice, the answer would be "niche". An organism's niche is where that certain organism fits into an ecosystem, or what their part to play is.
Answer:
temperature and precipitation
