Http://www.phschool.com/science/biology_place/biocoach/bioprop/folding.html hope it helpps
The nutrients in some soils could be toxic to microorganisms/fish in those ponds or lakes.
Because you cannot test it or observe it.
A scientific theory are created through the scientific method, in the scientific method you need to be able observe it and experiment.
A stem is what keeps the plant together and supports their leaves
B. STEMS
