3.3 biology test

Facilitated diffusion

is diffusion through transport proteins.

What is a main difference between diffusion and facilitated diffusion?

is the movement of a substance across a membrane, due to a difference concentration, without any help from other molecules.

three types of solutions.

isotonic: equilibrium Hypertonic solution: hyper= high, Cell will shrivel and die.- more hypotonic: hypo = low, cell will burst-less

vesicle transport

Endocytosis moves materials into the cell. Phagocytosis - solid particles Pinocytosis - liquid dropletsExocytosis - moves materials out of the cell

Explain why passive transport does not require energy

No energy is needed because the substances are moving from an area where they have a higher concentration to an area where they have a lower concentration.

What is osmosis? What type of transport is it?

Osmosis is a special type of diffusion — the diffusion of water molecules across a membrane.

Describe how simple diffusion proceeds. What kind of molecules can move across the membrane by simple diffusion?

Substances that can squeeze between the lipid molecules in the plasma membrane by simple diffusion are generally very small, hydrophobic molecules, such as molecules of oxygen and carbon dioxide.

why do materials move across membranes

concentration differences.

Active transport: movement of molecules from a region of lower to higher concentration. This is against concentration gradient.

movement of molecules from a region of lower to higher concentration. This is against concentration gradient.

Explain active transport.

occurs when energy is needed for a substance to move across a plasma membrane.

How is water transported across the membrane?

osmosis

What are the two types of transport proteins? Describe how they function.

oxygen and carbon dioxide

what is the sodium-potassium pump?

sodium-potassium pump, sodium ions are pumped out of the cell, and potassium ions are pumped into the cell.

Osmosis

the diffusion of water across a semipermeable membrane from an area of higher water concentration to an area of lower water concentration. Video

Passive transport

the movement of molecules across a cell membrane without requiring energy.

diffusion

the movement of molecules from a region of higher concentration to a region of lower concentration.