Material through which water flows is permeable. This material can be either natural or artificial. Naturally permeable material can be clean sand and gravel for example, or a sandstone and in the latter case the sandstone can have both porosity which is not synonymous with permeability as the pores must be connected to be permeable. An impermeable membrane could be used to line ditches for example to prevent leakage near mines.
The correct answer is a dichotomous key. Basically, you use the key to decide what species an organism is by looking at what traits it has, and if it doesn't have some traits you can instantly rule out a large number of species which brings you closer to your answer of what the species is that you're looking at.
<span>Two prokaryotes turning into a eukaryotic cell began with a process called
endosymbiosis. One large prokaryote engulfs (a process called
endocytosis) one small, aerobically respiring prokaryote. The small
prokaryote turned into a membrane-bound organelle, which prokaryotes do
not have, and like we know, only eukaryotes have membrane-bound
organelles. So that is how the eukaryotic cell structure evolved from
prokaryotic cells, meaning that before this evolution, they were most likely symbiotic.</span>
