CCEA A Level Biology: how the 260 marks across A2 1, A2 2 and the Practical Skills paper are structured, the unit-conversion and definition mix-ups that recur in examiner reports, and legal calculator techniques for standard deviation, Hardy-Weinberg and dilution questions.
閱讀時間 3 分鐘更新於: 2026年9月3日
試卷概覽
卷數
3
總分
260
考試時間
5小時 45分鐘
題型
12
試卷
時間
分數
題數
比重
題型
A2 1
2小時 15分鐘
100
9
40%
Short answer and data analysis, Extended synthesis essay
A2 2
2小時 15分鐘
100
9
40%
Short answer, genetics crosses and data analysis, Extended synthesis essay
A2 3, practical skills
1小時 15分鐘
60
8
20%
Practical methods, statistical evaluation and experimental design
評級
A*ABCDEU
計算機規定
Scientific calculators with statistical functions are permitted and expected throughout the A2 papers, particularly for standard deviation, Hardy-Weinberg and other statistical calculations in A2 3, where a printed statistics and formulae sheet is provided in the exam itself. The standard JCQ rule applies: no computer algebra or symbolic manipulation function, no communication with another device, and no retrievable information of any kind, including formulae, notes or programs, stored in the calculator. Clear the calculator's memory before the exam or activate its exam mode; the printed statistics sheet supplies the formulae, not the calculator's memory.
AO1: Demonstrate knowledge and understanding of scientific ideas, processes, techniques and procedures. (33%)
AO2: Apply knowledge and understanding of scientific ideas, processes, techniques and procedures in a theoretical context, in a practical context, when handling qualitative data, and when handling quantitative data. (42%)
AO3: Analyse, interpret and evaluate scientific information, ideas and evidence to make judgements and reach conclusions, and to develop and refine practical design and procedures. (25%)
用途: Get an accurate sample standard deviation without re-deriving the formula by hand under time pressure.
使用時機: Any question that asks you to calculate or use a standard deviation from a set of data, for example in A2 3 practical evaluation.
步驟
Enter the calculator into statistics list mode, key in each data value, then read the standard deviation directly from the statistics menu, checking you have selected the sample version with the n minus 1 denominator rather than the population version, since some calculators label them differently.
考試提示: This uses the calculator's ordinary statistics mode live during the exam with data you enter from the question. CCEA and JCQ rules do not allow any formula, note or program to be stored in the calculator beforehand; the statistics and formulae sheet is provided on paper for that reason. Activate exam mode if your calculator has one.
Hardy-Weinberg without losing track of p and q
Casio fx-83/85 series (scientific)
用途: Keep allele and genotype frequencies distinct so the calculation stays valid.
使用時機: Population genetics questions that give a genotype frequency and ask for an allele frequency, or the reverse.
步驟
Take the square root of the given genotype frequency on the calculator immediately to get the allele frequency, and write down which letter, p or q, you have just found. Then calculate the remaining allele frequency as 1 minus that value.
考試提示: This is a step-by-step calculation performed during the exam using the calculator's square root and arithmetic keys. No formula or worked method may be pre-stored in the calculator; everything must be entered fresh from the question.
Chaining a haemocytometer dilution calculation
Casio fx-83/85 series (scientific)
用途: Stop small conversion errors from compounding across a multi-step dilution and depth calculation.
使用時機: Cell counting questions using a haemocytometer, where the count must be corrected for chamber depth and any dilution factor.
步驟
Work out the count per square, the chamber depth conversion and the dilution factor as one continuous chain of multiplications and divisions on the calculator, rather than rounding after each step and re-entering the rounded number.
考試提示: This is a live, on-the-fly calculation using the calculator's normal keys. Storing a ready-made dilution formula or method in the calculator's memory is not permitted under CCEA and JCQ rules; clear the calculator before the exam.
常見錯誤
1high涉及分數: 2Calculations and units
Haemocytometer and conduction velocity calculations mix millimetre and metre or millilitre and cubic millimetre units partway through the working, giving an answer wrong by a large factor even though the method is right.
如何避免: Convert every measurement to a single unit system before you start calculating, and write that unit next to each number as you work, not only at the final answer.
2high涉及分數: 2Population genetics
Allele frequency, p or q, is confused with genotype frequency, p squared or q squared, in Hardy-Weinberg questions, invalidating the whole calculation.
如何避免: Fix the notation before you calculate: p and q are allele frequencies, p squared, 2pq and q squared are genotype frequencies. Identify which one the question actually gives you before substituting.
3medium涉及分數: 1Enzymes and hormones
Competitive inhibition or hormone receptor blocking is described only as blocks the enzyme or receptor, without stating that the inhibitor is a complementary shape that binds the active or receptor site.
如何避免: State the mechanism specifically: the inhibitor has a shape complementary to the active site or receptor and binds there, preventing the normal substrate or hormone from binding.
4high涉及分數: 4Extended writing
In the Section B extended essay, candidates list correct points without integrating them into a mechanistic explanation tied to the specific scenario in the question.
如何避免: Before writing, list every distinct point relevant to the scenario given, then write each one as a full explanatory sentence connected to the context, not as a standalone fact.
5medium涉及分數: 1Genetics
Dominance, an interaction between alleles of the same gene, is confused with epistasis, an interaction between different genes, when describing inheritance patterns.
如何避免: Ask whether the genes involved are the same gene or two different genes. Same gene, different alleles, is dominance; different genes affecting the same characteristic is epistasis.
6medium涉及分數: 1Statistical tests
Statistical test answers give a probability value without stating the comparison to the 0.05 threshold or what that means for the null hypothesis.
如何避免: Always finish a statistical test with an explicit sentence: because the calculated value is greater than or less than the critical value at p equals 0.05, the null hypothesis is accepted or rejected.
7medium涉及分數: 1Muscle contraction
Muscle contraction is described only as the power stroke, without stating that ATP is specifically needed to break the cross-bridge and detach the myosin head from actin between strokes.
如何避免: State both roles of ATP separately: it powers the myosin head movement, and it is also required to detach the myosin head from actin so the cycle can repeat.
8medium涉及分數: 1Nervous coordination
Repolarisation and hyperpolarisation of the axon membrane are confused, or the closing of sodium channels is described as if it were the opening of potassium channels.
如何避免: Keep the two events and their gates separate: sodium channels inactivate to stop depolarisation, and potassium channels open afterwards to cause repolarisation and the brief hyperpolarisation that follows it.