Edexcel Maths Skills for OCR A Level Biology June 2023 Paper 3 | Edexcel数学技能在OCR A Level生物2023年6月Paper 3中的应用

📚 Edexcel Maths Skills for OCR A Level Biology June 2023 Paper 3 | Edexcel数学技能在OCR A Level生物2023年6月Paper 3中的应用

This revision guide bridges the core mathematical techniques taught in Edexcel A Level Mathematics and the quantitative questions that frequently appear in OCR A Level Biology Paper 3, including the June 2023 Unified Biology paper. The 2023 paper continued to reward candidates who could calculate accurately, interpret data and justify statistical choices.

本复习指南连接了 Edexcel A Level 数学中训练的核心技术与 OCR A Level 生物 Paper 3 中常出现的定量题，包括 2023 年 6 月 Unified Biology 试卷。2023 年试卷继续奖励那些能准确计算、解读数据并合理解释统计选择的考生。

1. Units, Prefixes and Standard Form | 单位、词头与科学计数法

OCR Biology Paper 3 assumes you can move quickly between metres, millimetres, micrometres and nanometres, and write very small or very large values in standard form. Edexcel Mathematics trains the same index laws used in these conversions.

OCR 生物 Paper 3 默认你能快速在米、毫米、微米和纳米之间换算，并用科学计数法书写非常小或非常大的数值。Edexcel 数学训练的指数运算规则正是这些换算的基础。

1 mm = 10⁻³ m, 1 μm = 10⁻⁶ m, 1 nm = 10⁻⁹ m

Always convert to the same unit before calculating magnification or concentration. For example, a cell length of 75 μm is 75 × 10⁻⁶ m, which is 7.5 × 10⁻⁵ m in standard form.

在计算放大倍数或浓度前，始终先换算成相同单位。例如，75 μm 的细胞长度为 75 × 10⁻⁶ m，科学计数法写作 7.5 × 10⁻⁵ m。

2. Percentages and Percentage Change | 百分数与百分比变化

Mass, length and rate data are often compared using percentage change. The formula is (final value – initial value) ÷ initial value × 100.

质量、长度和速率数据常用百分比变化进行比较。公式为（最终值 – 初始值）÷ 初始值 × 100。

percentage change = (final – initial) ÷ initial × 100

If a potato chip in sucrose solution changes from 4.20 g to 3.78 g, the calculation is (3.78 – 4.20) ÷ 4.20 × 100 = -10.0%. The negative sign shows a loss in mass.

如果蔗糖溶液中的马铃薯条从 4.20 g 变为 3.78 g，计算为 (3.78 – 4.20) ÷ 4.20 × 100 = -10.0%。负号表示质量下降。

3. Magnification and Scale | 放大倍数与比例尺

Magnification questions require the equation magnification = image size ÷ actual size, with both lengths in the same unit. Edexcel ratio and proportion skills help you rearrange this equation quickly.

放大倍数题需要公式：放大倍数 = 图像尺寸 ÷ 实际尺寸，两个长度必须使用相同单位。Edexcel 的比与比例技能能帮助你快速变形该公式。

M = I ÷ A

If an image is 25 mm long and the actual organelle is 5 μm long, convert 25 mm to 25 000 μm, then M = 25 000 ÷ 5 = 5000×.

如果图像长度为 25 mm，实际细胞器长度为 5 μm，先把 25 mm 换算为 25 000 μm，则 M = 25 000 ÷ 5 = 5000×。

4. Dilutions and Concentrations | 稀释与浓度

Serial dilutions are common in Paper 3 practical analysis. The dilution factor is the ratio of final volume to stock volume, and the equation C₁V₁ = C₂V₂ works for simple dilutions.

连续稀释在 Paper 3 实验分析中很常见。稀释因子是最终体积与原液体积之比，简单稀释可用 C₁V₁ = C₂V₂ 计算。

C₁V₁ = C₂V₂

Adding 1 cm³ of stock to

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