AP Biology Final Exam Review (Ch 7: Membrane Structure/Function)

Front

What are integral proteins and why are they considered amphipathic?

Back

Integral proteins are proteins that span the entire membrane and have both hydrophilic (water-attracting) and hydrophobic (water-repelling) regions, making them amphipathic.

Front

Define hydrophilic. What role does it play in membrane structure?

Back

Hydrophilic means 'water-loving.' In membrane structure, hydrophilic regions interact with the aqueous environment, helping to stabilize the membrane and facilitate the movement of substances.

Front

What is passive ion diffusion?

Back

Passive ion diffusion is the movement of ions across a membrane without the use of energy, following their concentration gradient.

Front

What effect does blocking passive ion channels have on ion diffusion?

Back

Blocking passive ion channels stops ion diffusion completely, as ions can no longer move across the membrane.

Front

Explain the concept of an electrochemical gradient. How is it used in cells?

Back

An electrochemical gradient is a difference in ion concentration and charge across a membrane. Cells use it to drive processes like the import of nutrients against their concentration gradient.

Front

What is secondary active transport (cotransport)?

Back

Secondary active transport (cotransport) is a mechanism where the movement of one substance down its gradient drives the movement of another substance against its gradient.

Front

Describe the difference between primary and secondary active transport.

Back

Primary active transport directly uses ATP to move substances against their gradient, while secondary active transport uses the energy from the movement of another substance down its gradient.

Front

What happens to molecular movement when a cell reaches equilibrium with its environment?

Back

At equilibrium, molecules continue to move in and out of the cell randomly, but there is no net change in concentration.

Front

Define facilitated diffusion. How does it differ from simple diffusion?

Back

Facilitated diffusion is the process of transporting substances across a membrane with the help of transport proteins, unlike simple diffusion which does not require proteins.

Front

What is osmosis?

Back

Osmosis is the diffusion of water across a selectively permeable membrane, moving from an area of lower solute concentration to an area of higher solute concentration.