📚 Year 8 AQA Biology Formula & Theorems Quick-Reference | Year 8 AQA 生物公式定理速查手册
This quick-reference guide covers the essential formulas, equations, and key theorems you need for Year 8 AQA Biology. Master these to solve calculations, interpret data, and explain biological processes with confidence.
本速查手册涵盖 Year 8 AQA 生物学必需的公式、方程和关键定理。掌握这些内容，你就能自信地完成计算、解读数据并解释生物过程。
1. Magnification Formula | 放大倍数公式
Magnification is the number of times larger an image is compared to the real size of the object. Use the triangle method: cover the letter you need to find, then multiply or divide the other two letters.
放大倍数是图像比物体实际尺寸大的倍数。使用三角形方法：遮住你需要求的字母，然后对其他两个字母进行乘或除运算。
Magnification = Image size ÷ Actual size
放大倍数 = 图像尺寸 ÷ 实际尺寸
Rearranged forms:
变形公式：
- Image size = Magnification × Actual size | 图像尺寸 = 放大倍数 × 实际尺寸
- Actual size = Image size ÷ Magnification | 实际尺寸 = 图像尺寸 ÷ 放大倍数
Always convert the units so that the image size and actual size are in the same unit before calculating (e.g., both in mm or both in μm).
计算前务必转换单位，使图像尺寸和实际尺寸使用同一单位（例如都以毫米或微米表示）。
2. Photosynthesis Word Equation | 光合作用文字方程式
Photosynthesis is the process by which green plants and some other organisms use light energy to convert carbon dioxide and water into glucose and oxygen.
光合作用是绿色植物及某些其他生物利用光能将二氧化碳和水转化为葡萄糖和氧气的过程。
Carbon dioxide + Water → Glucose + Oxygen
二氧化碳 + 水 → 葡萄糖 + 氧气
This reaction requires light energy and chlorophyll. The rate of photosynthesis can be affected by light intensity, carbon dioxide concentration, and temperature.
该反应需要光能和叶绿素。光合作用速率受光照强度、二氧化碳浓度和温度的影响。
The balanced chemical equation (for reference): 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
配平化学方程式（供参考）：6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
3. Aerobic Respiration Word Equation | 有氧呼吸文字方程式
Aerobic respiration releases energy from glucose in the presence of oxygen. It takes place continuously in the mitochondria of living cells.
有氧呼吸在有氧气存在时从葡萄糖中释放能量。它在活细胞的线粒体中持续进行。
Glucose + Oxygen → Carbon dioxide + Water (+ Energy)
葡萄糖 + 氧气 → 二氧化碳 + 水（+ 能量）
The energy released is used for life processes such as growth, movement, and keeping warm (in mammals). The word ‘energy’ is placed in brackets because it is not a chemical substance.
释放的能量用于生命活动，如生长、运动和保持体温（哺乳动物）。”能量”一词加括号是因为它不是化学物质。
4. Anaerobic Respiration in Animals | 动物无氧呼吸
When oxygen is limited, animal cells can switch to anaerobic respiration. This produces far less energy and leads to the formation of lactic acid.
当氧气不足时，动物细胞可转为无氧呼吸。这种方式产生的能量少得多，并会形成乳酸。
Glucose → Lactic acid (+ Energy)
葡萄糖 → 乳酸（+ 能量）
The build-up of lactic acid causes muscle fatigue and cramps. During recovery, lactic acid must be oxidized back to carbon dioxide and water using extra oxygen (oxygen debt).
乳酸积累会导致肌肉疲劳和抽筋。恢复期间，乳酸必须被氧化，消耗额外的氧气（氧债）重新转化为二氧化碳和水。
5. Anaerobic Respiration in Plants and Yeast | 植物与酵母的无氧呼吸
In plant cells and yeast, anaerobic respiration produces ethanol and carbon dioxide instead of lactic acid. This process is called fermentation.
在植物细胞和酵母中，无氧呼吸产生乙醇和二氧化碳，而非乳酸。这一过程称为发酵。
Glucose → Ethanol + Carbon dioxide (+ Energy)
葡萄糖 → 乙醇 + 二氧化碳（+ 能量）
Fermentation is used in baking (CO₂ makes bread rise) and in brewing (ethanol is the alcohol in beer and wine).
发酵用于烘焙（二氧化碳使面包膨发）和酿酒（乙醇即啤酒和葡萄酒中的酒精）。
6. Enzyme Activity and Temperature | 酶活性与温度
Enzymes are biological catalysts that speed up reactions. Each enzyme has an optimum temperature at which its activity is greatest. For most human enzymes, this is around 37 °C.
酶是加速反应的生物催化剂。每种酶都有其活性最强的温度，大多数人体酶的最适温度约为 37 °C。
As temperature increases, enzyme activity rises because molecules move faster and collide more often. However, if the temperature exceeds the optimum, the enzyme’s active site changes shape (denatures) and activity falls sharply.
温度升高时，酶活性上升，因为分子运动加快，碰撞更频繁。但若温度超过最适值，酶的活性部位会改变形状（变性），活性急剧下降。
Key theorem: Enzyme activity follows a bell-shaped curve with temperature: it increases to an optimum, then rapidly declines due to denaturation.
关键定理： 酶活性随温度呈钟形曲线：先上升到最适值，随后因变性而迅速下降。
7. Enzyme Activity and pH | 酶活性与酸碱度
Each enzyme also has an optimum pH. For example, stomach protease (pepsin) works best at pH 2, whereas intestinal enzymes often prefer a pH around 7–8.
每种酶也有其最适 pH。例如，胃蛋白酶（胃蛋白酶）在 pH 2 时活性最强，而肠道酶通常偏好 pH 7–8 左右。
If the pH moves too far from the optimum, the enzyme’s active site changes shape and the enzyme denatures, losing its catalytic function permanently.
若 pH 偏离最适值过远，酶的活性部位改变形状，酶变性，永久失去催化功能。
Key theorem: Extreme pH values disrupt the ionic and hydrogen bonds that hold the enzyme’s shape, leading to irreversible denaturation.
关键定理： 极端 pH 值会破坏维持酶形状的离子键和氢键，导致不可逆的变性。
8. Surface Area to Volume Ratio & Diffusion | 表面积体积比与扩散
Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration. The rate of diffusion is influenced by the surface area to volume ratio (SA:V).
扩散是净粒子从高浓度区域向低浓度区域的移动。扩散速率受表面积体积比（SA:V）的影响。
Surface area to volume ratio = Surface area ÷ Volume
表面积体积比 = 表面积 ÷ 体积
A larger SA:V allows faster diffusion because there is more membrane surface for particles to cross relative to the internal volume. This is why cells are small, and why organisms have specialised exchange surfaces like alveoli and villi.
较大的 SA:V 允许更快的扩散，因为相对于内部体积，有更多的膜表面让粒子通过。这就是细胞较小以及生物体具有肺泡和小肠绒毛等特化交换表面的原因。
Key theorem: As an object gets bigger, its SA:V decreases. This limits the size of unicellular organisms and explains the need for transport systems in multicellular organisms.
关键定理： 随着物体变大，其 SA:V 下降。这限制了单细胞生物的尺寸，也解释了多细胞生物需要物质运输系统的原因。
9. Osmosis and Water Potential | 渗透与水势
Osmosis is the net movement of water molecules through a partially permeable membrane from a dilute solution (high water potential) to a concentrated solution (low water potential).
渗透是水分子通过部分透性膜从稀溶液（高水势）向浓溶液（低水势）的净移动。
There is no single equation for osmosis, but you can calculate the percentage change in mass of plant tissue to compare water movement.
渗透没有单一公式，但你可以计算植物组织质量的变化百分比来比较水分移动。
Percentage change in mass = ((Final mass – Initial mass) ÷ Initial mass) × 100%
质量变化百分比 =（（最终质量 – 初始质量）÷ 初始质量）× 100%
A positive value indicates water gained by osmosis; a negative value indicates water lost. Water potential is a measure of the tendency of water to move; pure water has the highest water potential.
正值表示渗透吸水，负值表示渗透失水。水势是水移动趋势的量度；纯水具有最高的水势。
10. Genetic Diagrams and Punnett Squares | 遗传图解与旁氏方格
Genetic crosses predict the probability of offspring inheriting specific traits. You can use a Punnett square to combine parental gametes.
遗传杂交可预测后代遗传特定性状的概率。你可以使用旁氏方格来组合亲本配子。
For a monohybrid cross (one gene with two alleles), the expected genotypic ratio may be:
对于单基因杂交（一个基因有两个等位基因），预期的基因型比可能为：
- Homozygous dominant : Heterozygous : Homozygous recessive = 1 : 2 : 1
- 纯合显性 : 杂合子 : 纯合隐性 = 1 : 2 : 1
If one allele is dominant, the phenotypic ratio often simplifies to 3 : 1 (dominant phenotype : recessive phenotype).
如果其中一个等位基因是显性，表型比通常简化为 3 : 1（显性表型 : 隐性表型）。
Key theorem: In a Punnett square, each cell represents a possible combination of alleles with an equal chance of occurring, provided fertilisation is random.
关键定理： 在旁氏方格中，每个格子代表一种可能的等位基因组合，并且所有组合发生的机会均等，前提是受精是随机的。
11. Biomass and Energy Transfer | 生物量与能量传递
Biomass is the total mass of living material at each trophic level. Only about 10% of the energy in one trophic level is transferred to the next level; the rest is lost through respiration, waste, and uneaten material.
生物量是每个营养级中活物质的总质量。从一个营养级传递到下一级的能量仅为约 10%；其余通过呼吸、排泄和未被采食而流失。
Efficiency of energy transfer = (Energy transferred to next level ÷ Energy available at previous level) × 100%
能量传递效率 =（传递至下一级的能量 ÷ 上一级可用的能量）× 100%
Pyramids of biomass are usually pyramid-shaped because biomass decreases along a food chain. You can draw pyramids to scale by calculating the dry biomass of each level.
生物量金字塔通常呈金字塔形，因为沿着食物链生物量递减。可通过计算每一级的干生物量按比例绘制金字塔。
12. Calculating Mean and Sampling | 计算平均值与取样
When taking repeated measurements in biology, the mean (average) is used to improve reliability and reduce the effect of random errors. It is calculated by summing all values and dividing by the number of values.
在生物学中进行重复测量时，使用平均值（平均数）可提高可靠性并减少随机误差的影响。计算方法是将所有数值相加后除以数值的个数。
Mean = (Sum of values) ÷ (Number of values)
平均值 =（数值总和）÷（数值个数）
When sampling organisms with a quadrat, you can estimate a population size using:
使用样方调查生物时，可通过下式估算种群数量：
Estimated population = (Mean count per quadrat) × (Total area ÷ Quadrat area)
估计种群数量 =（每样方平均计数）×（总面积 ÷ 样方面积）
Always place quadrats randomly to avoid bias and take enough samples to ensure a reliable mean.
应随机放置样方以避免偏差，并采集足够样本以确保平均值可靠。
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