IGCSE Biology: Diffusion, Osmosis, and Active Transport

Flashcards comparing diffusion, osmosis, and active transport in IGCSE Biology.

Diffusion

Movement of molecules from a region of higher concentration to a region of lower concentration.

Type of Transport for Diffusion

Passive (does not require energy)

Does Diffusion require a membrane?

No

Direction of Movement in Diffusion

Down the concentration gradient (high to low)

Example of Diffusion in Biology

Oxygen and carbon dioxide gas exchange in lungs.

Osmosis

Movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane.

Type of Transport for Osmosis

Passive (does not require energy)

Does Osmosis require a membrane?

Yes (partially permeable membrane)

Direction of Movement in Osmosis

Down the water potential gradient (high to low)

Example of Osmosis in Biology

Water absorption in plant roots.

Active Transport

Movement of molecules or ions from a region of lower concentration to a region of higher concentration using energy (ATP).

Type of Transport for Active Transport

Active (requires energy in the form of ATP)

Does Active Transport require a membrane?

Yes (usually through carrier proteins in the membrane)

Direction of Movement in Active Transport

Against the concentration gradient (low to high)

Example of Active Transport in Biology

Mineral ion uptake in plant roots and glucose absorption in the small intestine.