AS Edexcel Biology: Formula & Theorem Quick Reference | AS Edexcel 生物：公式定理速查手册

📚 AS Edexcel Biology: Formula & Theorem Quick Reference | AS Edexcel 生物：公式定理速查手册

Mastering key formulas and theorems is essential for success in AS Edexcel Biology. This quick-reference guide compiles all the critical equations and principles you need for calculations, data analysis, and understanding biological processes across Topics 1–4.

掌握关键公式和定理对于 AS Edexcel 生物学的成功至关重要。本速查手册汇编了您需要在计算、数据分析和理解生物过程（涵盖主题 1–4）中使用的所有重要方程式和原理。

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1. Microscopy and Magnification | 显微镜与放大倍数

Magnification (M) = Image size (I) / Actual size (A). Always convert all lengths to the same unit (e.g. mm to μm: ×1000).

放大倍数 (M) = 图像尺寸 (I) ÷ 实际尺寸 (A)。始终将所有长度转换为相同单位（例如 1 mm = 1000 μm）。

Rearranged forms: I = M × A and A = I / M. Remember to measure the image in the same unit, e.g. millimetres on a print.

变形公式：I = M × A 以及 A = I ÷ M。请记住用相同单位测量图像，例如打印标尺的毫米数。

For scale bars: measure the bar length on the image; the actual length is given on the bar. Magnification = measured bar length / actual length.

对于比例尺：测量图像上比例尺的长度；实际长度在比例尺上标注。放大倍数 = 测量的尺长 ÷ 实际长度。

Conversion factors: 1 cm = 10 mm; 1 mm = 1000 μm; 1 μm = 1000 nm.

单位换算：1 cm = 10 mm；1 mm = 1000 μm；1 μm = 1000 nm。

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2. Surface Area to Volume Ratio | 比表面积与体积比

Surface area to volume ratio (SA:V) = Surface area / Volume. For a cube of side L, SA = 6L², Volume = L³, so SA:V = 6/L.

比表面积 (SA:V) = 表面积 ÷ 体积。对于边长为 L 的立方体，SA = 6L²，体积 = L³，因此 SA:V = 6/L。

A higher SA:V ratio promotes faster diffusion, which is why cells and organisms have evolved flattened shapes or transport systems.

较高的 SA:V 比促进更快的扩散，这就是为什么细胞和生物进化出扁平形状或运输系统的原因。

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3. Diffusion and Fick’s Law | 扩散与菲克定律

Rate of diffusion ∝ (surface area × concentration difference) / thickness of membrane. This is expressed as Fick’s Law: Rate = k (A × ΔC) / d, where k is the diffusion coefficient.

扩散速率 ∝ (表面积 × 浓度差) ÷ 膜厚度。表示为菲克定律：速率 = k (A × ΔC) / d，其中 k 为扩散系数。

Factors that increase diffusion rate: larger surface area, steeper concentration gradient, shorter diffusion distance, and higher temperature. Adaptations like thin alveolar walls maximise gas exchange.

增加扩散速率的因素：更大的表面积、更陡的浓度梯度、更短的扩散距离和更高的温度。像薄的肺泡壁等适应性结构能最大化气体交换。

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4. Cardiovascular Formulas | 心血管公式

Cardiac output (CO) = Heart rate (HR) × Stroke volume (SV). CO is measured in L min⁻¹; HR in beats per minute (bpm); SV in L per beat.

心输出量 (CO) = 心率 (HR) × 每搏输出量 (SV)。CO 单位为 L min⁻¹；HR 为每分钟心跳次数；SV 单位为升/次。

BMI = body mass (kg) / (height in metres)². A BMI over 30 is classified as obese; a very low BMI indicates underweight, both affecting cardiovascular health.

BMI = 体重 (kg) ÷ (身高 米)²。BMI 超过 30 被视为肥胖；极低的 BMI 表示体重不足，两者均影响心血管健康。

Waist-to-hip ratio is used to assess fat distribution. It is calculated as waist circumference / hip circumference.

腰臀比用于评估脂肪分布，计算公式为腰围 ÷ 臀围。

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5. Lung Volumes and Ventilation | 肺容量与通气量

Pulmonary ventilation (minute volume) = tidal volume × breathing rate. Tidal volume is the volume of air inhaled/exhaled per breath; breathing rate is breaths per minute.

肺通气量（每分钟通气量）= 潮气量 × 呼吸频率。潮气量为每次呼吸吸入或呼出的空气量；呼吸频率为每分钟呼吸次数。

FEV₁/FVC ratio: Forced Expiratory Volume in 1 second divided by Forced Vital Capacity. A ratio below 0.7 suggests obstructive airway disease such as COPD.

FEV₁/FVC 比值：一秒用力呼气量 ÷ 用力肺活量。比值低于 0.7 提示阻塞性气道疾病如 COPD。

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6. Enzyme Rate Calculations | 酶反应速率计算

Rate of reaction = change in product concentration / time or change in substrate concentration / time. For colour-based assays, rate can be expressed as 1 / time taken for a standard colour change.

反应速率 = 产物浓度变化 ÷ 时间 或 底物浓度变化 ÷ 时间。对于比色法测定，速率可表示为 1 ÷ 达到标准颜色变化所需时间。

To find initial rate: draw a tangent to the curve at time zero and calculate its gradient. Gradient = Δ[product] / Δt.

求初始速率：在时间零点作曲线的切线，并计算其斜率。斜率 = Δ[产物] ÷ Δt。

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7. Photosynthesis Rate and Respiratory Quotient | 光合速率与呼吸商

Rate of photosynthesis = volume of O₂ produced / time or 1 / time for indicator colour change. Net photosynthesis = Gross photosynthesis − Respiration.

光合速率 = 产生 O₂ 的体积 ÷ 时间 或 1 ÷ 指示剂变色时间。净光合作用 = 总光合作用 − 呼吸作用

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