Paper 2 · Cell Structure and Membranes
The glycocalyx is a layer of carbohydrate chains attached to proteins and lipids on the outer surface of the cell surface membrane. What is the primary function of the glycocalyx?
AActing as a store of chemical energy for active transport across the membrane.
BEnabling cell recognition, by acting as receptor sites for hormones and antigens.
CCatalysing the hydrolysis of ATP to actively pump ions across the membrane.
DProviding structural support by forming covalent cross links between adjacent phospholipid molecules.
Explanation: The carbohydrate chains of the glycocalyx project from the outer face of the membrane and act as recognition sites: they let similar cells recognise one another and group into tissues, and they act as receptors for chemical signals such as hormones and neurotransmitters, and as antigens recognised by the immune system. The glycocalyx has no role in energy storage, ATP hydrolysis, or covalently linking phospholipids.
Derived from ZIMSEC Biology Paper 2, November 2008, Q16
