Biological Membranes
Revision Activity
Complete the exercises below to help you revise and test your knowledge of biological membranes. We also recommend you refer to pages
88-91 (membrane structure) and 110-120 (membrane transport) in your ebook. Remember to write down any questions you have so you
can ask your tutor or lecturer to help you with concepts you don’t understand. For further hints and tips on studying Biology please go to the
Biology Learning Skills section of the LMS.
Revise the topic:
First, please watch the YouTube clip at: http://www.youtube.com/watch?v=mnE_hT3eN6g
Then test your knowledge by completing the following questions.
1. The structure of the plasma membrane
a) Label the following diagram of an animal cell membrane:
Letter
Name
____________ Phospholipid bilayer
____________ Integral Protein
____________ Fatty acid tails
___________ Phosphate heads
___________ Peripheral protein
___________ Cholesterol
___________ Glycoprotein
___________ Glycolipids
Biological Membranes
Revision Activity
b) Fill in the gaps in the sentences below
a. The plasma membrane is mainly composed of four molecules; _________________________ in a bilayer, protein, _______________________
and in animal membranes ______________________________. It is also referred to as the ___________________________________ because the
lipid molecules and some of the proteins move laterally within the membranes.
b. Each phospholipid molecule consists of 2 parts: the polar head which is____________________________ (attracted to water) and a
pair of non polar tails which are ____________________________________(repelled by water).
c. In the lipid bilayer, the polar heads the outer layer of phospholipids faces the _________________________ fluid and the polar heads
of the inner layer of phospholipids faces the _______________________ fluid.
d. __________________________, when it is present, makes the plasma membrane stable, stronger and more flexible.
e. There are 2 types of proteins associated with the plasma membrane: ___________________________ proteins, which are loosely
associated with the membrane surface and __________________________________ proteins which interact with the inner hydrophobic
regions of the membrane. These can extend right through the membrane.
Biological Membranes
Revision Activity
2. Movement across membranes
Revise these concepts by completing the following concept map to categorise the ways that substances can cross the membrane.
TYPES OF
MOVEMENT
ACTIVE
TRANSPORT
PASSIVE
TRANSPORT