Where does the exchange of materials between a cell and its environment take place?

Answer 1

a cell membrane

Answer 2

A cell's contents are enclosed by a bilayer of phospholipid molecules, each of which has a head group attracted to water and a tail repelled by it. This bilayer is called a membrane and regulates traffic into and out of the cell. There are five types of transport across membranes in cells: diffusion, facilitated diffusion, active transport, cotransport and endocytosis/exocytosis.

1. DiffusionFacilitated and Active Transport
2. Diffusion is the motion of solutes from a region of high concentration to areas of low concentration; over time, diffusion causes solutes to become evenly distributed throughout a liquid, much as a drop of dye added to a glass of water will eventually diffuse throughout the water. Cotransport, Endocytosis and Exocytosis
3. Urea, carbon dioxide, water and oxygen are among the substances that can diffuse across cell membranes. Charged ions and many other important substances like glucose either do not diffuse across the membrane or do so very slowly. In facilitated transport, a carrier protein embedded in the membrane acts like a revolving door to permit substances concentrated on either side of the membrane to flow to the other. In active transport, by contrast, a protein uses energy to actively pump a substance across the membrane.
4. Cotransport is a form of active transport where a membrane-embedded protein uses a concentration gradient of one substance to power the cross-membrane transport of another. If, for example, the cell pumps hydrogen ions out, it could create a high extracellular concentration of hydrogen ions and use this gradient to power inward transport of another molecule like sucrose. In endocytosis, the cell membrane envelops food particles or other molecules and takes them in as a membrane-enclosed sac. Exocytosis is the reverse of endocytosis.

Answer 3

Cell Membrane

Answer 4

the cell/plasma membrane.