A2 1: Physiology, Co-ordination and Control, and Ecosystems

What A2 1 covers

• Homeostasis: the kidney, water balance and osmoregulation
• Temperature control and negative feedback
• The nervous system, nervous transmission and synapses
• Muscle structure and contraction
• Hormonal co-ordination in plants and animals
• Photosynthesis: light-dependent and light-independent stages
• Respiration and ATP production
• Ecosystems, energy flow, nutrient cycles and succession

Assessment: Written paper — structured questions plus extended response with QWC credit. The definitive content statements are published by CCEA at ccea.org.uk.

Where marks get lost

• Explaining the loop of Henle without the counter-current multiplier and water potential of the medulla.
• Describing an action potential out of sequence, or omitting the refractory period's role.
• Writing about photosynthesis products without stating where ATP and reduced NADP are used.

Question styles to drill

• Synapse questions that ask you to explain unidirectionality or the effect of a named drug.
• Data on nephron filtrate composition — apply selective reabsorption rather than recall it.
• Energy-flow calculations: percentage efficiency between trophic levels, with reasons for losses.

Other CCEA A2 units

• A2 2 · Biochemistry, Genetics and Evolutionary Trends
• A2 3 · Practical Skills in A2 Biology