BIO Unit 2 test

• Diffusion is the process of molecules moving from high concentration to low concentration.

• Diffusion can occur with or without a membrane.

• Phospholipids are one of the principal components of cell membranes (along with membrane proteins).

• A concentration gradient is the difference between the concentration of a particular molecule in one area compared to the area across the membrane.

• Phospholipid structure determines its properties.

• Phospholipids are amphipathic molecules, meaning they have hydrophilic and hydrophobic regions.

• Phospholipids form bilayers in water due to their polar and nonpolar physical properties.

• Membrane proteins are diverse in terms of structure, position in the membrane, and function.

• Cell membranes are fluid, meaning they are not fixed in position and can adopt amorphous shapes.

• Cell membranes are semipermeable.

• Particles move across membranes by simple diffusion, facilitated diffusion, osmosis, and active transport.

• Describe the structure of the cell membrane in terms of the phospholipid bilayer and embedded proteins, and explain its role in controlling the movement of substances in and out of the cell.

• Explain diffusion as the net movement of molecules from an area of higher concentration to lower concentration down a concentration gradient.

• Describe how the surface area to volume ratio affects the rate of diffusion in cells.

• Define osmosis as the movement of water molecules across a partially permeable membrane from a region of higher water potential to lower water potential.

• Describe the effects of osmosis on animal and plant cells, including lysis, crenation, turgidity, and plasmolysis.

• Explain active transport as the movement of molecules against a concentration gradient using energy from ATP.

• Compare and contrast diffusion, osmosis, and active transport, highlighting their energy requirements and movement of substances.

• Describe the role of carrier proteins in facilitated diffusion and how it differs from simple diffusion.

Skills

• Drawing of the fluid-mosaic model

• Estimation of osmolarity in tissues by bathing samples in hypotonic and hypertonic solutions

• Distinguishing between scatterplot and bar graphs

• Interpretation of graphs

• Describing trends