IGCSE Biology Chapter 3: Movement Into and Out of Cells

A set of vocabulary flashcards based on the Chapter 3 IGCSE biology lecture covering the mechanisms of diffusion, osmosis, and active transport.

Diffusion

The net movement of particles from a region of higher concentration to a region of lower concentration (down a concentration gradient) as a result of their random movement.

Kinetic Energy

The energy derived from the random movement of molecules and ions which provides the energy for diffusion.

Equilibrium

The state reached when both sides have equal amounts of particles and there is no more net movement or exchange rate.

Gaseous Diffusion

The process by which molecules like glucose and oxygen for respiration, or carbon dioxide for exchange in the lungs, move to required locations.

Cell Membrane

The key barrier that controls which substances move into and out of the cell, often acting as a partially permeable membrane.

Concentration Gradient

The difference in concentration between two regions; maintaining a high to low gradient ensures constant diffusion before equilibrium is reached.

Osmosis

The net movement of water molecules from a region of higher water potential (a dilute solution) to a region of low water potential (a concentrated solution) through a partially permeable membrane.

Solvent

The primary role of water in living organisms, facilitating essential processes such as digestion, excretion, and transport.

Partially Permeable Membrane

A membrane that allows some substances to pass through or penetrate while blocking others, usually based on molecule size.

Hypertonic (Animal Cell)

A condition where water leaves the cell because the external water potential is lower, causing the cell to shrink or shrivel.

Isotonic

A state where the water potential outside the cell is the same as the water potential inside, resulting in no net movement of water.

Hypotonic (Animal Cell)

A condition where water moves into the cell due to higher external water potential, which may cause the cell to burst in a process known as plasmolysis.

Turgid

A state where a plant cell becomes firm because water enters the cell and the resulting pressure of the water pushes outwards on the cell wall.

Flaccid (Plant Cell)

A state where the cytoplasm of a plant cell shrinks and pulls away from the cell wall due to water loss in a hypertonic solution.

Dialysis Tubing

Also known as visking tubing, this material has small pores and is used in experiments to act as a partially permeable membrane to demonstrate osmosis.

Active Transport

The movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration (against a concentration gradient) using energy from respiration.

Protein Carriers

Structures present in the cell membrane that use energy to bind and shuttle molecules or ions across the membrane during active transport.

Ion Uptake

A critical process in root hair cells where minerals from the soil enter the plant against the concentration gradient via active transport.