SEC G2 Science (Chemistry, Biology) is syllabus code K225, and its candidates sit Papers 3, 4, 5 and 6 — the Chemistry pair and the Biology pair — selected from a six-paper suite, for 100 marks in total. K225 is the life-sciences pairing, and it is the G2 science combination that lines up most naturally with health, nursing and applied life-science diplomas. Ancourage Academy teaches all three pairings, and this guide covers the paper selection, paired session timing, the absence of a practical paper at G2, and what the pairing supports afterwards. Our secondary science programmes group students by pairing.
Which Four Papers a K225 Candidate Sits
K225 candidates take Papers 3 and 4 for Chemistry and Papers 5 and 6 for Biology: SEAB writes six papers across the G2 science suite — two per science — and each syllabus code selects the four matching its two subjects, so K225 skips the Physics pair.
| Paper | Science | Type | Marks | Sat by K225? |
|---|---|---|---|---|
| Paper 1 | Physics | Multiple choice, 20 questions | 20 | No |
| Paper 2 | Physics | Structured | 30 | No |
| Paper 3 | Chemistry | Multiple choice, 20 questions | 20 | Yes |
| Paper 4 | Chemistry | Structured | 30 | Yes |
| Paper 5 | Biology | Multiple choice, 20 questions | 20 | Yes |
| Paper 6 | Biology | Structured | 30 | Yes |
Paper numbers are fixed to the science rather than to the order sat, so Paper 3 is always Chemistry multiple choice and Paper 5 is always Biology multiple choice, whichever pairing a candidate is entered for. The other codes select differently: K223 (Physics, Chemistry) takes Papers 1, 2, 3 and 4, and K224 (Physics, Biology) takes Papers 1, 2, 5 and 6.
The four papers total 100 marks — 40 from multiple choice and 60 from structured questions, split evenly between the two sciences.
How the Paired Sessions Are Timed
SEC G2 Science (Chemistry, Biology), K225, pairs Chemistry Papers 3 and 4 in one session of 1 hour 15 minutes and Biology Papers 5 and 6 in another, with candidates advised not to spend more than 30 minutes on the multiple-choice Papers 3 and 5.
- Session A — Papers 3 and 4 (Chemistry): multiple choice then structured, sharing one 1 hour 15 minute clock.
- Session B — Papers 5 and 6 (Biology): the same structure and the same 30-minute advisory on the multiple-choice half.
- The structured half carries more marks. 30 against 20. The advised split leaves both halves at the same rate — two-thirds of a mark a minute — so overrunning on multiple choice simply borrows from the bigger paper.
- Practise the pair. Sitting a structured paper alone never rehearses the pacing decision that decides the session.
K225 is the pairing where the 30-minute advisory bites hardest in both sessions, because Chemistry and Biology structured questions both reward written explanation rather than short numerical answers. A candidate who overruns on either multiple-choice half compresses the part of the session that pays best.
No Separate Practical Paper at G2
G2 science has no standalone practical examination. Practical work is expected across the course, with at least four practical tasks expected from each component science’s own list — eight across Chemistry and Biology — and experimental skills and investigations are assessed inside the written papers at approximately 10% of the marks.
The numbering makes this easy to get wrong, so it is worth being exact. At G3, Combined Science includes a separate Paper 5 practical assessment under syllabuses K326, K327 and K328. At G2 no practical paper exists, and Paper 5 refers to the Biology multiple-choice paper instead.
For K225 candidates the experimental content matters twice over, since both Chemistry and Biology structured papers can ask about apparatus, variables, controls, sources of error and interpretation of results. Our science practical preparation guide covers those skills, and they transfer directly into written experimental questions.
Who the Chemistry and Biology Pairing Suits
K225 is the life-sciences pairing, and it suits students heading towards nursing, health sciences, applied science and biotechnology diplomas, where a chemistry foundation alongside biology is genuinely useful.
- The two sciences reinforce each other. Biological processes are chemical processes; a student who understands bonding and reactions reads respiration and digestion more easily.
- Written explanation is the shared currency. Both halves reward precise terminology and structured reasoning more than calculation, so one study method serves both.
- Physics is absent. Routes with a strong physical or engineering component will need that background elsewhere.
- It is a full science subject. Two sciences at the G2 standard, not a reduced option.
Our guide to Combined Science versus Pure Science covers the wider choice, and the Sec 3 subject combination guide covers when the decision is made.
How K225 Compares with the G3 Route
The G3 counterpart, K328, is a different examination: four papers including a practical assessment, 200 marks in total, at the former O-Level standard.
| Aspect | G2 Science, Chemistry and Biology (K225) | G3 route (K328) |
|---|---|---|
| Papers sat | Four, selected from a six-paper suite | Four, including a practical assessment |
| Total marks | 100 | 200 |
| Practical examination | None — assessed within the theory papers | Yes, a separate practical assessment |
| Session structure | Paired papers, 1h 15min per pair | Separate papers |
| Exam standard | Former N(A)-Level standard | Former O-Level standard |
| Counts for JC L1R4 | No | Yes |
Our G2 vs G3 subject levels guide covers how levels are set and reviewed under Full Subject-Based Banding, and the SEC replaces the O-Level for G3 subjects from 2027.
Where a K225 Grade Counts, Including Nursing
G2 science grades appear on the SEC certificate and count for polytechnic and Polytechnic Foundation Programme routes; junior college and Millennia Institute aggregates from 2028 must be built entirely from G3 subjects.
MOE's JC and MI admission criteria state that "All subjects used in aggregate score computation for JC and MI admissions must be taken at G3."
The polytechnic side is where K225 pays. MOE's polytechnic diploma course page sets the general bar, for admissions from the 2028 Post-Secondary Admissions Exercise onwards, as an ELR2B2 net aggregate that "must not exceed 22", with the Diploma in Nursing scored on a separate ELR2B2-C net aggregate that "must not exceed 24". Note that clearing an aggregate is necessary but not sufficient — each diploma also sets its own minimum entry requirements, which is where the science pairing itself is read. Our post-secondary pathways guide covers the routes in detail.
Revising Two Sciences That Share a Method
K225 is the pairing where a single study method serves both halves, because Chemistry and Biology at G2 both reward precise terminology and structured written explanation.
- Build one terminology discipline across both. Vague paraphrase loses marks a student believes they earned, in either science.
- Use the overlap deliberately. Revise bonding and reaction basics before the biological processes that depend on them.
- Weekly: one timed pair, alternating Session A and Session B, with a hard stop on the multiple-choice half.
- Track the sciences separately. A middling overall mark commonly hides one strong and one weak half.
- Drill experimental questions in both. Our guide to using past-year papers effectively sets out an error-analysis routine that applies to structured science papers.
Where science sits near a promotion threshold, our guide to what counts towards Sec 3 promotion explains how subject marks are counted, and a trial class (usually $18) starts with a timed paired session.
Common Questions About SEC G2 Science (Chemistry, Biology)
What is the syllabus code for G2 Science with Chemistry and Biology?
It is K225, listed by SEAB among the G2 Cambridge subjects as "Science (Chemistry, Biology)". The other two G2 science pairings are K223, Science (Physics, Chemistry), and K224, Science (Physics, Biology).
Which papers does a K225 candidate take?
Papers 3, 4, 5 and 6. SEAB writes six papers across the G2 science suite, two for each of Physics, Chemistry and Biology, and each code selects the four matching its sciences. K225 takes the Chemistry pair (Papers 3 and 4) and the Biology pair (Papers 5 and 6), totalling 100 marks. Papers 1 and 2, which are Physics, are not sat.
Is there a practical paper in K225?
No. G2 science has no standalone practical examination. Practical work is expected during the course, with at least four practical tasks expected from each component science’s own list — eight across Chemistry and Biology — and experimental skills and investigations are assessed within the written papers at approximately 10% of the marks. Paper 5 at G2 is the Biology multiple-choice paper, not a practical assessment.
Is K225 good preparation for a nursing diploma?
SEC G2 Science (Chemistry, Biology), K225, is relevant preparation for nursing, since chemistry and biology both underpin health-science content. Admission is scored on the ELR2B2-C net aggregate for the Diploma in Nursing, which MOE states must not exceed 24, against a general polytechnic bar of 22 (both from the 2028 Post-Secondary Admissions Exercise, the first a K225 cohort can enter). Clearing the aggregate is necessary but not sufficient — each diploma sets its own minimum entry requirements, so check the specific course.
Does skipping Physics at G2 matter?
It depends entirely on the intended route. K225 covers Chemistry and Biology only, which suits life-science, health and applied-science pathways well. Routes with a strong physical or engineering component would need physics background built another way, so match the pairing to the intended diploma rather than choosing on comfort alone.