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C1.2.3—ATP ↔ ADP interconversions

ATP and ADP interconvert as ATP hydrolysis releases energy, while respiration and photosynthesis regenerate ATP from ADP and phosphate, supporting usable cellular work and measurable biological activity.

Syllabus
First assessment 2025
Objective
C1.2.3
Level
SL

Exam analysis

Chance of appearing2%of analysed past papers
Latest appearanceMay 2025
Most common paperPaper1
Typical marks1–3

Common command terms

  • Identify
  • State

Recent exam appearances

May 2025Paper1B ["SL"] · TZ13(c)[ 3 ]C1.2.3—ATP ↔ ADP interconversions
November 2021Paper2 ["SL"] · TZ04(b)(i)[ 1 ]C1.2.3—ATP ↔ ADP interconversions
November 2017Paper1 ["SL"] · TZ012[ 1 ]C1.2.3—ATP ↔ ADP interconversions
Practice this objective

Coverage 2017–2025 · Updated 15 Jul 2026

Concept essentials

  • ATP hydrolysis releases energy for cellular work.
  • ADP plus inorganic phosphate can be phosphorylated to form ATP.
  • Respiration and photosynthesis can produce ATP.
  • ATP is rapidly regenerated rather than permanently stored.
ConceptIB Biology SL