9693_s26_ms_31 — 2026 May-June Marine Science 9693 Mark Scheme 3 Variant 1 · Cambridge CAIE AS & A Level

Writing in bullet points instead of continuous prose for Section B 'explain' and 'discuss' questions

“It is expected that candidates write their answers in continuous prose for Section B questions, as stated in the specification. Those writing bullet points often could not be credited as the bullet points were not linked and consisted of a list of terms and short statements in a random and unclear sequence. This was particularly the case for 'explain' and 'discuss' questions, where the linking is essential for candidates to demonstrate they have a depth of understanding.”— 9693 Paper 1, May/June 2025

How to fix: Use one- or two-word bullet points in the margin as scaffolding ONLY, then write the actual answer in linked sentences. Each sentence must connect to the next using cause-and-effect words: 'because', 'so', 'this means', 'as a result'. Bullets in the answer space lose marks even if the content is correct.

Giving own definitions instead of the precise specification definitions

“There are a few definitions within the specification that candidates are expected to know and be able to precisely state what the terms mean. Salinity is one of those, defined as 'the concentration of dissolved salts in sea water'. However, few candidates were able to give the specification definition, often just stating 'the amount of salt' rather than using any scientific terminology in their definition.”— 9693 Paper 1, May/June 2025

How to fix: Build a flashcard set of every term the syllabus marks as a definition: salinity, productivity, ion, tidal range, ecosystem, biodiversity, mutualism, parasitism, bioaccumulation, biomagnification, stenohaline, euryhaline, osmoconformer, osmoregulator. Memorise the EXACT specification wording — not your own paraphrase. 'Salinity = the concentration of dissolved salts in sea water', not 'the amount of salt'.

Confusing pairs of similar marine science terms

“Candidates should also ensure that they understand the difference between biological terms such as bioaccumulation and biomagnification and between stenohaline and euryhaline.”— 9693 Paper 3, May/June 2025

How to fix: Drill the key marine pairs: bioaccumulation (build-up WITHIN one organism over time) vs biomagnification (increase in concentration ALONG a food chain at higher trophic levels); stenohaline (narrow salinity tolerance) vs euryhaline (wide salinity tolerance); osmoconformer (body-fluid salinity tracks the surroundings) vs osmoregulator (body-fluid salinity kept constant). Write a one-line definition for each and use the term in a sentence; never use the pair as if they mean the same thing.