This memory aid covers Memory Aids within The Nitrogen Cycle for GCSE Biology. The nitrogen cycle: nitrogen-fixing, nitrifying, denitrifying bacteria, ammonification, and the role of legumes It is section 10 of 14 in this topic. Use it for quick recall, then test yourself straight afterwards so the memory aid becomes usable in an answer.
Topic position
Section 10 of 14
Practice
15 questions
Recall
15 flashcards
🧠 Memory Aids
The four types of bacteria — "FNAD" (Fix, Nitrify, Ammonify, Denitrify):
- F — Fix: Nitrogen-fixing bacteria convert N₂ → ammonia
- N — Nitrify: Nitrifying bacteria convert ammonia → nitrites → nitrates
- A — Ammonify: Decomposers convert dead proteins → ammonia
- D — Denitrify: Denitrifying bacteria convert nitrates → N₂
Remember: "FNAD sounds like 'FED' — bacteria FEED the cycle."
Nitrifying vs Denitrifying — which one is "good" for farmers?
Nitrifying bacteria = NIce for farming (they make NItrates)
Denitrifying bacteria = DEstructive for farming (they DEstroy nitrates)
The conditions trick — aerobic vs anaerobic:
- Nitrifying bacteria need AIR (aerobic) → well-drained soil
- Denitrifying bacteria hate AIR (anaerobic) → waterlogged soil
Legume mnemonic — "Beans Put Nitrogen in Soil" (BPNS):
- Beans (and peas, clover)
- Partner with Rhizobium bacteria
- Nitrogen fixed in root nodules
- Soil enriched with nitrates after decomposition
What nitrogen is used for in organisms — "PAD-C":
- Proteins (amino acids)
- Amino acids (building blocks of proteins)
- DNA (nucleotides contain nitrogen)
- Chlorophyll (contains a nitrogen ring)