There are two classes of membrane transport proteins—carriers<span> and </span>channels<span>. Both form continuous </span>protein<span> pathways across the lipid bilayer. Whereas transport by </span>carriers<span> can be either active or passive, solute flow through </span>channel proteins<span> is always passive.</span>
They start as single cell orginisms then they evolve from there.
hope that helps
Answer:
The answer to your question is B.
The part of the experiment in which the experimental factor has been removed is referred to as <span>the independent variable. </span>The dependent variable<span> is the element which is being measured in an experiment or evaluated in a mathematical equation.</span>
