Expert study guides, comprehensive exam structures, historical weightings, calculator methodologies, and common candidate mistakes for OCR A Level Biology A (H420).
阅读时间 4 分钟更新于: 2026年6月21日
试卷概览
卷数
3
总分
270
考试时间
6小时
题型
3
试卷
时间
分数
题数
比重
题型
Biological processes
2小时 15分钟
100
51
37%
選擇題 (MCQ), Structured Short Answer, Level of Response Essay
Biological diversity
2小时 15分钟
100
48
37%
選擇題 (MCQ), Structured Short Answer, Level of Response Essay
Unified biology
1小时 30分钟
70
19
26%
Structured Short Answer, Level of Response Essay
评级
A*ABCDEU
计算器规定
A scientific or graphical calculator that meets JCQ regulations may be used (some GCSE Mathematics and Science papers are non-calculator). Graphical calculators must be set to exam mode; you must clear any stored programs, notes or data before the exam, and the calculator must not be able to retrieve stored text or formulae.
根据历届试题与评分标准整理（2022–2024）。
计算器程序
Graph: zeros, intersections & turning points
Graphical calculator / GDC (exam mode)
用途: Plot a function to read its roots (zeros), points of intersection, and maxima/minima.
使用时机: Checking solutions, sketching, or solving where an analytic method is hard.
步骤
Graph the function(s) and use the built-in zero, intersect and maximum/minimum tools.
考试提示: Allowed under JCQ rules, but you must still show your method — an unsupported calculator answer earns no method marks. Clear all stored programs, notes and data (graphical calculators in exam mode) before the exam.
Numerical equation solver
Graphical calculator / GDC (exam mode)
用途: Solve an equation or find a variable numerically when an algebraic route is long or implicit.
使用时机: Iterative or implicit equations, or to confirm an algebraic solution.
步骤
Use the equation/zero solver, entering the equation and a sensible starting estimate.
考试提示: Allowed under JCQ rules, but you must still show your method — an unsupported calculator answer earns no method marks. Clear all stored programs, notes and data (graphical calculators in exam mode) before the exam.
Numerical integration & differentiation
Graphical calculator / GDC (exam mode)
用途: Evaluate a definite integral \(\int_a^b f(x)\,dx\) or a gradient \(f'(x)\) at a point.
使用时机: Checking calculus answers, or where only a numerical value is needed.
步骤
Use the GDC's numeric integral / derivative function with the limits or the point.
考试提示: Allowed under JCQ rules, but you must still show your method — an unsupported calculator answer earns no method marks. Clear all stored programs, notes and data (graphical calculators in exam mode) before the exam.
Statistics & probability distributions
Graphical calculator / GDC (exam mode)
用途: 1-var/2-var statistics, linear regression, and cumulative binomial / normal / Poisson probabilities without tables.
使用时机: Statistics questions and hypothesis tests.
步骤
Enter data in the statistics editor, or use the distribution menu (binomial cdf, normal cdf, …).
考试提示: Allowed under JCQ rules, but you must still show your method — an unsupported calculator answer earns no method marks. Clear all stored programs, notes and data (graphical calculators in exam mode) before the exam.
常见错误
1high涉及分数: 3Ecosystems
Failing to calculate and plot frequency density when plotting histograms where class intervals are unequal.
如何避免: Always calculate frequency density (frequency divided by class width) for each interval when plotting histograms with variable category widths.
2medium涉及分数: 1Populations and sustainability
Omitting the negative sign in rates of change where a population or variable is declining.
如何避免: Double-check the direction of the trend. If the trend is downwards, ensure the rate value includes a negative sign.
3high涉及分数: 1Transport in plants
Suggesting that plant cutting procedures completely stop water loss rather than reduce it.
如何避免: Use conditional/relative language. State that the action 'reduces' or 'minimises' transpiration rather than stops it.
4medium涉及分数: 2Ecosystems
Using unspecific terms like 'nitrifying bacteria' when asked to describe nitrification.
如何避免: Name the specific genera: Nitrosomonas for converting ammonia to nitrites, and Nitrobacter for converting nitrites to nitrates.
5high涉及分数: 3Cell structure
Forgetting to convert units from millimeters to micrometers during microscope graticule calibration math.
如何避免: Convert micrometer scale measurements to the same base units (e.g., multiply mm by 1000 to get µm) before executing division steps.
6medium涉及分数: 2Cellular control
Stating that point mutations always modify the tertiary structure of proteins.
如何避免: Explain that due to the degeneracy of the genetic code, silent mutations can occur where the altered codon still codes for the same amino acid, leaving the protein unchanged.
7medium涉及分数: 1Transport in plants
Thinking that the Casparian strip acts as a barrier to the symplast pathway.
如何避免: Remember that the Casparian strip is a suberin barrier embedded in the cell walls, thus blocking the apoplast pathway and forcing water into the symplast pathway.