Mark Scheme

Polymers are large molecules found in every biological system. Each polymer has a structure that is related to its function. Write a description (i.e., describe) of how the structure of biological polymers is related to their function. [25 marks]

This is the list of the MAIN POINTS that would be looked for in the essay:

Polymers as:

• molecules associated with storage: Biological molecules, carbohydrates and proteins, The release of energy from carbohydrate, The control of blood glucose
• informational molecules: enzymes, DNA as genetic material, structure of nucleic acids, immunology, transport of respiratory gases
• structural molecules: cell ultrastructure, cell walls, biological molecules, carbohydrates and proteins

Examiners are also given instructions as follows: If the essay contains information from more than one area e.g. polymers associated with storage & structural molecules, 2 marks can be given; information from one area is awarded 1 mark generally. However, examiners are allowed some discretion in where information is drawn and this means that other study areas can be incorporated into the essay. For example, an examiner would be able to consider awarding marks for incorporating plant & microbial biology too as this is just as relevant to polymers as vital biological molecules.

How marks are awarded:

Each awarding body has slightly different values to how marks are awarded and / or where certain criteria fall.

This is a general idea of where marks for Essay 3 would be awarded.

• Scientific Content: maximum of 16 marks depending upon coverage of topic areas (in depth, superficial), occurrence of biological / scientific errors
• Breadth of Knowledge: maximum of 3 marks depending upon how many areas of the title have been covered (see Main Points above), if any topic areas essential to basic biological understanding have been omitted, if you have covered more than one area in the main points (little credit is given to writing about just one of the main areas e.g.. storage)
• Relevance: maximum of 3 marks & this speaks for itself. If you start writing or drawing about something other than surface area & its linked topics, marks will be lost. The only occasion where you can put in something less relevant is the introduction but, better to keep to the topic rigidly.
• Quality of language: maximum of 3 marks and this also speaks for itself. This is all about good English, good scientific language (no terms like “great big thing” “huge” “amount” or other weak, vague language)