Guided notes covering material from Topic 1.4 of the updated IB Biology syllabus for 2016 exams. Notes sequence and prompts are based on the Oxford IB Biology textbook by Allott and Mindorff.

1. IB Biology Chapter 1 Notes: Membrane Transport (1.4) NAME:
Word Definition
Passive transport
Transport down a concentration gradient across a semi-permeable membrane that
does not require energy
Active transport
Transport across a semi-permeable membrane that does require energy and is
usually up a concentration gradient
Diffusion The movement of materials from a high concentration to a low concentration
Concentration
gradient
The differences in concentration when comparing two locations
Simple diffusion Diffusion through the phospholipids
Facilitated diffusion Diffusion through a transport protein
Osmosis
The movement of water down water’s concentration gradient; from a lower solute
concentration to a higher solute concentration
Endocytosis
The process of bringing a large molecules into the cell trough engulfing the material
in the membrane. This requires energy
Exocytosis
The process of releasing large molecules out of the cell through the fusion of a
vesicle with the cell membrane. This requires energy

2. 1.4.2 The fluidity of
membranes allows materials
to be taken into cells by
endocytosis orreleased by
exocytosis.
1.4.3 Vesicles move
materials within cells.
1.4.1 Particles move across
membranes by simple
diffusion, facilitated
diffusion, osmosis, and
active transport.
Outline how cells intake materials by endocytosis:
Outline how cells secrete or release materials by exocytosis:
Describe the function of vesicles in cells, specifically how they are used to excrete proteins formed on
the Rough Endoplasmic Reticulum:
Simple Diffusion:
Facilitated Diffusion:
Osmosis:
Active Transport:

3. 1.4.4 Describe the structure
and function of sodium-
potassiumpumps for active
transport and potassium
channels for facilitated
diffusion in axons.
1.4.6 Estimate osmolarity in
tissues by bathing samples in
hypotonic and hypertonic
solutions.
1.4.5 Understand that tissues
or organs to be used in
medical procedures must be
bathed in a solution with the
same osmolarity as the
cytoplasmto prevent
osmosis.
Sodium-Potassium Pump:
What type of cell transport is used? _______________________________
Describe the function:
Axon Potassium Channels:
What type of cell transport is used? _______________________________
Describe the function:
Define the following terms:
Osmolality:
Isotonic solution:
Hypertonic solution:
Hypotonic solution:
What would happen to the mass of water in a tissue sample in each of the following solutions?
Isotonic:
Hypertonic:
Hypotonic:
Explain why tissues ororgans must be stored in isotonic solutions:
Normal saline (salt solution), isotonic to human cells, is used in many medical procedures.List some
examples of its usage: