The document outlines different transportation mechanisms across cellular membranes. It details osmosis and facilitated diffusion, which do not require energy and move substances along the concentration gradient, as well as active transport, which requires energy and moves substances against the gradient. The selectivity of these mechanisms varies, affecting what substances can be transported.

1. Complete this table:
Solution
Transport mechanism concentration gradient Energy requirement Selectivity Osmosis Along
the concentration gradient No energy required Only solvent molecules Facilitated diffusion
Along the concentration gradient No energy required Solutes including mineral ions Active
transport Against the concentration gradient Energy required Solutes, mineral ions, small organic
molecules