Unit 1.2 Transport Across Cell Membranes

What does the cell membrane consist of?

Phospholipids and proteins

What term describes the cell membrane?

Selectively permeable

What does selectively permeable mean?

Allows only some substances to pass through the cell

Describe passive transport

Occurs down the concentration gradient, does not require energy

Name the two types of passive transport and describe them

Diffusion - Movement of molecules down a concentration gradient from a higher to a lower concentration

Osmosis - Movement of water molecules from a higher to a lower water concentration

Describe active transport

Movement of molecules against the concentration gradient from a lower to a higher concentration, requires energy

Give two differences between passive and active transport

Active transport requires energy whereas passive doesn’t

Active moves against the concentration gradient whereas passive moves down

What would happen to an animal cell placed in a solution that is higher than its cell contents?

Take up water by osmosis and burst

What would happen to an animal cell placed in a solution that is lower than its cell contents?

Lose water by osmosis and shrink

What would happen to a plant cell in a solution higher than its cell contents?

Take up water by osmosis and become turgid

What would happen to a plant cell placed in a solution lower than its cell contents?

Lose water by osmosis and become plasmolysed