All Biology GCE A Level courses currently studied are in two parts, with a number of separate units or modules in each part. Some units are further divided into subunits and some have options to allow you to follow a specific path of interest. Some Examination Boards offer alternative externally marked practical examinations or the internal assessment of practical skills (subject to moderation).

In using this Revision Guide most students will have already completed the first half of the course, AS (Advanced Subsidiary). Some students will study both AS and A2 in one year. Some will go on to study the second part of the A Level course, called A2. Both groups of students are advised to use the Letts AS and A2 Revision Guides.

Advanced Subsidiary is assessed at the standard expected halfway through an A Level course, i.e. between GCSE and A Level. This means that AS and A2 courses are designed so that difficulty steadily increases:

• AS Biology builds from GCSE Science/ Biology
• A2 Biology builds from AS Biology.

IMPORTANT NOTE! Each Examination Board has included a common core of subject content in AS and in A2. Beyond the common core material the Examination Boards have included more varied content.

What are the differences between AS and A2?
There are three main differences:
(i) A2 includes the more demanding concepts. (Understanding will be easier if you have completed the AS Biology course as a ‘stepping stone'.)
(ii) There is a much greater emphasis on the skills of application and analysis than in AS. (Using knowledge and understanding acquired from AS is essential.)
(iii) A2 includes a substantial amount of synoptic material. (This is the drawing together of knowledge and skills across the modules of AS and A2.