A. atom
atoms are described to be the basic unit of a chemical element.
five ways in which a membrane can deal with the materials are:
1. it keeps molecules out
2.allowing molecules to enter anytime.
3.sometimes it allow molecules at certain times.
4.hydrophobic molecules can go with ease because it can dissolve in the lipid bi layers.
5.large external materials can be taken by the cell through endoctytosis.
If there is a full article/story on this please post it.
Model it literally says a plastic replica