Correct me if I'm wrong, but I don't think you'd really need a definition of the management functions, rather a basic outline of the roles they must complete within an organisation;
Finance (accounting) - Look after the financial aspect of an organisation and prepare Balance Sheets, Profit and Loss statements etc. and make decisions based on these figures
Operations (Production) - Monitor the production line of an organisation, and ensure they are meeting OH&S laws etc.
Research and Development - Are the inventors of an organisation, and decide on new products,services etc.
Sales and Marketing - They develop marketing campaigns in order to maximise their sales (fairly straight forward)
Human Resource Management - Look after the rights and welfare of staff within an organisation to ensure they aren't being discriminated against, receive fair wages etc.
I'm sure you can come up with better definitions than mine, they don't have to be word for word perfect, if anything you won't be asked to define REsearch and Development but rather be able to list conflicts which may arise against these functions of management.