Membrane Transport

What are the two main types of membrane transport?

Passive transport and active transport.

What is passive transport?

Movement across the membrane that does not require energy.

What are the three types of passive transport?

Simple diffusion, facilitated diffusion and osmosis.

What is a concentration gradient?

A difference in concentration between two regions.

What does moving along the concentration gradient mean?

Moving from high concentration to low concentration.

What does moving against the concentration gradient mean?

Moving from low concentration to high concentration.

What is simple diffusion?

The passive movement of solutes from high concentration to low concentration directly through the phospholipid bilayer.

What is facilitated diffusion?

The passive movement of particular ions or molecules from high concentration to low concentration through membrane proteins.

What is the main difference between simple diffusion and facilitated diffusion?

Simple diffusion occurs directly through the phospholipid bilayer, while facilitated diffusion uses channel or carrier proteins.

What is osmosis?

The passive movement of water across a semipermeable membrane from an area of low solute concentration to an area of high solute concentration.

In terms of water concentration, which direction does water move during osmosis?

From high water concentration to low water concentration.

What is an isotonic solution?

A solution with a similar solute concentration to the cell, causing no net movement of water.

What is a hypotonic solution and what happens to cells in it?

It has a lower solute concentration than the cell, so water enters; animal cells swell and plant cells become turgid.

What is a hypertonic solution and what happens to cells in it?

It has a higher solute concentration than the cell, so water leaves; animal cells shrivel and plant cells become plasmolysed.

Why does an animal cell shrink in a hypertonic solution?

Water moves out of the cell by osmosis because the surrounding solution has a higher solute concentration.

What is active transport?

Movement of substances from low concentration to high concentration against the concentration gradient using energy.

What provides the energy for active transport?

ATP.

Compare active and passive transport.

Passive transport requires no energy and moves substances along the concentration gradient, while active transport requires energy and moves substances against the gradient.

What is endocytosis?

An energy-requiring process where large substances or bulk amounts of smaller substances enter the cell.

What is phagocytosis?

A type of endocytosis in which solid substances are engulfed by the cell.

What is pinocytosis?

A type of endocytosis in which liquids or dissolved substances are taken into the cell.

What is exocytosis?

An energy-requiring process where vesicles fuse with the membrane and release their contents outside the cell.

What process moves water from wet soil into plant roots?

Osmosis.

What process moves mineral ions from a low concentration in soil into a higher concentration inside a root cell?

Active transport.

What process occurs when a white blood cell engulfs a bacterium?

Phagocytosis.

What process moves oxygen from the lungs into the blood?

Simple diffusion.

What process moves glucose from high concentration to low concentration through a carrier protein?

Facilitated diffusion.

What is the difference between osmosis and simple diffusion?

Osmosis is specifically the movement of water across a semipermeable membrane, while simple diffusion is the movement of solute particles from high concentration to low concentration.

Why is maintaining a relatively constant internal environment important?

It allows enzymes and metabolic processes to function effectively.