CCEA AS Biology · AS 2
AS 2: Organisms and Biodiversity
Gaseous exchange, transport in plants and mammals, adaptation, biodiversity, classification, sampling and human impact.
- Level
- CCEA AS
- Weighting
- 40% of AS, 16% of the full A-level
- Exam
- AS 2 written paper (1 hour 30 minutes)
What AS 2 covers
- Gaseous exchange in plants, mammals, fish and insects
- Transport and transpiration in flowering plants
- Transport in mammals: heart, vessels, blood and tissue fluid
- Adaptations of organisms to their environment
- Biodiversity, classification and sampling techniques
- Human impact on biodiversity and conservation
Assessment: Written paper — structured questions plus an extended-response question with QWC credit. The definitive content statements are published by CCEA at ccea.org.uk.
Where marks get lost
- Explaining transpiration as 'water being sucked up' rather than cohesion-tension with a water potential gradient.
- Describing the cardiac cycle without linking pressure changes to valve opening and closing.
- Giving tissue fluid formation without hydrostatic and oncotic (solute) pressure terms.
Question styles to drill
- Data questions on transpiration rate using a potometer — units, controls and limitations.
- Comparing gas exchange surfaces against the same three criteria: surface area, thinness, maintained gradient.
- Sampling calculations: quadrats, transects, percentage cover and species diversity index.
Practise AS 2 now
Generate 10 CCEA-worded AS 2 questions, or photograph a written answer and get it marked in CCEA mark-scheme language.