Okay, I would bend over backwards! :)
Leeuwenhoek was inspecting things under his artifial magnifying instrument and found single-cell living beings that he alluded to as protists.
Its either dead material or organisms that eat producers
Solid milk and solid food
Natural selection is the process in nature by which organisms better adapted to their environment tend to survive and reproduce more than those less adapted to their environment. For example, treefrogs are sometimes eaten by snakes and birds.