Carbon cycle — Normal
Apply the topic independently and explain your method. No hints during the test.
Includes extension practice
The carbon cycle is required. Nitrogen fixation, ammonium, nitrification, nitrate uptake and denitrification in this shared set are nitrogen-cycle extensions.
Easy, Normal and Difficult describe practice demand; they are not the official Core and Extended tiers.
- Cambridge 0654 syllabus2028–2029 · B18.3.1
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