Year 12 AQA Biology: Formula & Theorem Quick Reference | Year 12 AQA 生物：公式定理速查手册

📚 Year 12 AQA Biology: Formula & Theorem Quick Reference | Year 12 AQA 生物：公式定理速查手册

This quick reference handbook compiles all the essential formulas, equations, and key principles you need to master for Year 12 AQA Biology. From microscopy calculations to population genetics, every formula is presented with a clear explanation and the necessary context for AS-level examinations. Bookmark this guide for efficient revision and last-minute checks.

本速查手册汇集了 Year 12 AQA 生物学所需的所有关键公式、方程和核心原理。从显微镜计算到种群遗传学，每个公式都配有清晰的解释和适用于 AS 考试的必要背景。收藏本指南，便于高效复习和考前速览。

1. Microscopy Calculations | 显微镜计算

The magnification formula relates the image size you see or measure to the actual size of the specimen. It is fundamental for all microscope work in the AQA practicals.

放大倍数公式将你所看到或测量的图像大小与样本的实际尺寸联系起来。这是所有 AQA 显微镜实验工作的基础。

Actual size (A) = Image size (I) / Magnification (M)

Remember to ensure that both image size and actual size are expressed in the same unit, typically micrometres (µm). Common unit conversions: 1 mm = 1000 µm, and 1 nm = 0.001 µm.

请确保图像大小和实际尺寸使用相同的单位，通常为微米（µm）。常用单位换算：1 mm = 1000 µm，1 nm = 0.001 µm。

2. Surface Area to Volume Ratio & Fick’s Law | 表面积体积比与菲克定律

As an organism or cell increases in size, its surface area to volume ratio (SA:V) decreases. This limits the rate of exchange by diffusion alone. Fick’s Law describes the factors that influence the rate of diffusion across a membrane or tissue.

随着生物体或细胞体积增大，其表面积体积比（SA:V）会下降。这限制了仅靠扩散进行物质交换的速率。菲克定律描述了影响物质通过膜或组织扩散速率的因素。

Rate of diffusion ∝ (Surface Area × Concentration difference) / Diffusion distance

Maximising SA (e.g. villi, alveoli), maintaining a steep concentration gradient, and minimising diffusion distance (thin epithelium) are key adaptations seen in exchange surfaces. Fick’s Law provides the theoretical basis for understanding why such adaptations are necessary.

最大化表面积（如绒毛、肺泡）、维持陡峭的浓度梯度以及缩短扩散距离（薄的上皮组织）是交换表面常见的关键适应。菲克定律为理解这些适应为何必要提供了理论依据。

3. Cardiac Output | 心输出量

Cardiac output is a measure of the volume of blood pumped out of a ventricle per minute. It is a vital parameter for assessing circulatory system performance.

心输出量衡量心室每分钟泵出的血容量，是评估循环系统功能的重要指标。

Cardiac Output (CO, cm³ min⁻¹) = Heart Rate (HR, bpm) × Stroke Volume (SV, cm³)

For a typical resting adult, heart rate might be 70 bpm and stroke volume about 70 cm³, giving a CO of around 4900 cm³ min⁻¹. During exercise, both HR and SV increase, significantly raising CO.

典型静息的成年人，心率约为 70 bpm，每搏输出量约 70 cm³，心输出量约 4900 cm³ min⁻¹。运动时，心率和每搏输出量均会增加，大幅提高心输出量。

4. Respiratory Quotient (RQ) | 呼吸商

The respiratory quotient indicates the type of metabolic substrate being respired. It is the ratio of carbon dioxide produced to oxygen consumed, measured over a given time.

呼吸商指示正在被呼吸的代谢底物类型。它是一定时间内产生的二氧化碳量与消耗的氧气量之比。

RQ = Volume of CO₂ produced / Volume of O₂ consumed

Theoretical RQ values: 1.0 for pure carbohydrates, around 0.7 for lipids, and approximately 0.9 for proteins. By measuring RQ using a respirometer, you can infer which food type a cell or organism is predominantly using for respiration.

理论 RQ 值：纯碳水化合物为 1.0，脂质约为 0.7，蛋白质约为 0.9。通过呼吸计测量 RQ，你可以推断细胞或生物体主要利用哪种营养物进行呼吸。

5. Water Potential (Ψ) | 水势

Water potential determines the net movement of water. Water always moves from a region of higher water potential to one of lower water potential. It is measured in kilopascals (kPa).

水势决定水的净移动方向。水总是从水势较高的区域流向水势较低的区域。水势的单位是千帕（kPa）。

Water potential Ψ = Solute potential Ψₛ + Pressure potential Ψₚ

Solute potential (Ψₛ) is always negative or zero because dissolving solutes reduces free energy. Pressure potential (Ψₚ) is positive in turgid plant cells (pushing against the cell wall) and zero in open solutions or animal cells. At equilibrium, the water potential of the cell equals that of its surroundings

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