1. Active transport
1.4 Membrane transport
Cells & Biomolecule
movement of substances
across membranes using
energy in the form of ATP.
ATP
1.4 Membrane transport
Cells & Biomolecule
(adenosine triphosphate)
energy molecule.
Concentration
gradient
1.4 Membrane transport
Cells & Biomolecule
a gradient resulting from an
unequal distribution of ions
across the cell membrane.

2. Diffusion
1.4 Membrane transport
Cells & Biomolecule
passive movement of
particles from a region of
higher concentration to a
region of lower
concentration.
Endocytosis
1.4 Membrane transport
Cells & Biomolecule
the process in which the cell
takes in materials from the
outside by infolding of the
membrane to form a vesicle.
Exocytosis
1.4 Membrane transport
Cells & Biomolecule
the process in which the cell
releases materials to the
outside by discharging them
as membrane-bounded
vesicles that pass through
the cell membrane.

3. Facilitated diffusion
1.4 Membrane transport
Cells & Biomolecule
diffusion through a
membrane that requires
proteins.
Hypertonic
1.4 Membrane transport
Cells & Biomolecule
a more concentrated
solution relative to another
fluid.
Hypotonic
1.4 Membrane transport
Cells & Biomolecule
a less concentrated solution
relative to another fluid.

4. Osmoregulation
1.4 Membrane transport
Cells & Biomolecules
control of the water balance
of a living organism.
Osmosis
1.4 Membrane transport
Cells & Biomolecule
passive movement of water
molecules from a region of
lower solute concentration to
a region of higher solute
concentration.
Secretion
1.4 Membrane transport
Cells & Biomolecule
when material is released
from a cell.

5. Semi-permeable
membrane
1.4 Membrane transport
Cells & Biomolecule
membrane that allows some
substances to diffuse through
but not others. Transport pumps
proteins in the plasma
membrane that use ATP to
move substances across the
membrane. Vesicles a bubble-
like membranous structure that
stores and transports cellular
products.