📚 Year 12 WJEC Biology: Formula & Theorem Quick Reference Handbook | Year 12 WJEC 生物：公式定理速查手册
This quick-reference handbook compiles essential formulas, equations, and theorems required for Year 12 WJEC Biology. Mastering these relationships will strengthen your quantitative skills and help you tackle calculation-based exam questions with confidence.
本速查手册汇总了 Year 12 WJEC 生物所需的核心公式、等式与定理。掌握这些关系将强化你的量化技能，助力你自信应对涉及计算的试题。
1. Magnification and Actual Size | 放大率与实际大小
size (A) of a specimen. The formula is M = I / A, provided I and A are in the same units.
放大率(M)定义为图像大小(I)与实际大小(A)的比率。公式为 M = I / A，前提是 I 与 A 单位相同。
Magnification = Image size / Actual size
measures 20 mm at a magnification of ×4000, the actual size is 20 mm ÷ 4000 = 0.005 mm = 5 µm.
要计算实际大小，可转换公式：A = I / M。例如，图像在 ×4000 的放大率下长为 20 mm，实际大小为 20 mm ÷ 4000 = 0.005 mm = 5 µm。
Common unit conversions: 1 mm = 1000 µm; 1 µ . A useful trick is to convert everything to micrometres first and then apply the formula.
常见单位换算：1 mm = 1000 µm；1 µm = 1000 nm；1 nm = 1000 pm。计算前务必统一单位。一个实用的技巧是先将所有长度换算为微米再代入公式。
When measuring from a photomicrograph, always check whether a scale bar is given. If a scale bar is present, use it to determine the magnification or directly read the actual size.
从显微照片测量时，务必检查是否提供比例尺。如果有比例尺，可以利用它来确定放大率或直接读出实际大小。
2. Surface Area to Volume Ratio | 表面积与体积比
As an object increases in size, its surface area to volume ratio (SA:V) decreases. This is critical for exchange surfaces and heat loss in living organisms.
随着物体增大，其表面积与体积比 (SA:V) 降低。这对活体生物中的交换表面和热量散失至关重要。
For a cube: SA = 6 × side², V = side³, so SA:V = 6 / side
For a sphere: SA = 4πr2 and V = (4/3)πr3 ganisms rely on diffusion, so a high SA:V is essential. Multicellular organisms have adaptations like folded membranes and capillary networks to compensate for low SA:V.
对于球体：SA = 4πr2，V = (4/3)πr3，SA:V = 3 / r。单细胞生物依赖扩散，高 SA:V 至关重要。多细胞生物通过膜折叠和毛细血管网等适应来补偿较低的 SA:V。
tio drops to 3:1. This illustrates why larger organisms need specialised exchange systems.
示例：边长为 1 mm 的立方体，SA = 6 mm²，V = 1 mm³，比值为 6:1。若边长增至 2 mm，SA = 24 mm²，V = 8 mm³，比值降至 3:1。这说明为什么较大的生物需要特化的交换系统。
3. Rates of Reaction and Q10 | 反应速率与 Q10 系数
The rate of an enzyme-controlled reaction can be calculated by measuring the appearance of product or disappearance of substrate per unit time.
酶促反应速率可通过测量单位时间内产物的出现量或底物的消耗量来计算。
Rate = Change in product concentration / Time
Initial rate is measured early in the reaction when substrate concentration is not limiting. A tangent drawn on a progress curve at time zero gives the initial rate. For temperature sensitivity, the Q10 coefficient is used.
初始速率在反应早期底物浓度不受限时测量。在进程曲线上于时间零点处作切线可得到初始速率。对于温度敏感性，使用 Q10 系数。
Q10 = Rate at (T + 10°C) / Rate at T
Q10 is usually around 2 for enzyme-catalysed reactions, meaning the rate doubles for a 10°C rise, until denaturation occurs. If rates are measured at 20°C and 30
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