📚 Year 9 WJEC Biology: Quick Reference to Equations and Principles | WJEC Year 9 生物：公式定理速查手册
This quick reference handbook gathers all the essential equations, formulas and key scientific principles you will encounter in the Year 9 WJEC Biology course. Whether you are studying cells, respiration, photosynthesis, genetics or ecology, having these relationships at your fingertips will boost your confidence in class tasks and exam papers.
这本速查手册汇集了你在 Year 9 WJEC 生物学课程中会遇到的所有关键方程、公式和重要科学原理。无论你正在学习细胞、呼吸作用、光合作用、遗传还是生态学，随时查阅这些关系式都能增强你在课堂练习和考试中的信心。
1. Total Magnification in Microscopy | 显微镜总放大倍数
A light microscope uses two lenses to magnify specimens: the eyepiece lens (ocular lens) and the objective lens. The total magnification is the product of the magnifying power of these two lenses.
光学显微镜使用两个透镜来放大标本：目镜和物镜。总放大倍数是这两个透镜放大倍数的乘积。
Total magnification = Eyepiece magnification × Objective magnification
总放大倍数 = 目镜放大倍数 × 物镜放大倍数
For example, if the eyepiece lens is 10× and the objective lens is 40×, the image you see is magnified 400 times. This quick calculation helps you estimate the size of cells and structures under the microscope.
例如，如果目镜是 10×，物镜是 40×，你看到的图像被放大了 400 倍。这个快速计算可以帮助你估计显微镜下细胞和结构的尺寸。
| Eyepiece (目镜) | Objective (物镜) | Total Magnification (总放大倍数) |
|---|---|---|
| 10× | 4× | 40× |
| 10× | 10× | 100× |
| 10× | 40× | 400× |
2. Word Equation for Photosynthesis | 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 synthesise glucose from carbon dioxide and water. The overall word equation summarises the reactants and products.
光合作用是绿色植物和某些其他生物利用光能，将二氧化碳和水合成葡萄糖的过程。总的文字方程式概括了反应物和生成物。
carbon dioxide + water → glucose + oxygen
二氧化碳 + 水 → 葡萄糖 + 氧气
The arrow is read as ‘goes to’ in the presence of light energy and chlorophyll. Chlorophyll, found in chloroplasts, absorbs the light energy that drives this reaction. Oxygen is released as a by-product.
箭头表示在光能和叶绿素的参与下“生成”。存在于叶绿体中的叶绿素吸收驱动该反应的光能。氧气作为副产物被释放出来。
3. Symbol Equation for Aerobic Respiration | 有氧呼吸的化学符号方程式
Aerobic respiration occurs in the mitochondria of cells, using oxygen to break down glucose and release energy for cellular activities. The balanced symbol equation is a key concept in Year 9 biology.
有氧呼吸发生在细胞的线粒体中，利用氧气分解葡萄糖并释放能量供细胞活动使用。配平的化学符号方程式是 Year 9 生物学中的一个关键概念。
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O (+ energy)
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O（+ 能量）
Glucose (C₆H₁₂O₆) and oxygen (O₂) react to produce carbon dioxide (CO₂) and water (H₂O), while releasing energy stored as ATP. The six in front of O₂, CO₂ and H₂O shows that the equation is balanced according to the law of conservation of mass.
葡萄糖（C₆H₁₂O₆）与氧气（O₂）反应生成二氧化碳（CO₂）和水（H₂O），同时释放储存在ATP中的能量。O₂、CO₂ 和 H₂O 前面的 6 表明该方程式遵循质量守恒定律是配平的。
The same products – carbon dioxide and water – can be tested during respiration experiments. Carbon dioxide turns limewater milky, and water condenses as colourless droplets.
相同的产物——二氧化碳和水——可以在呼吸作用实验中进行检测。二氧化碳使石灰水变浑浊，水蒸气则冷凝为无色液滴。
4. Enzyme Activity and Optimum Conditions | 酶活性与最适条件
Enzymes are biological catalysts that speed up metabolic reactions. Each enzyme has an optimum temperature and pH where its activity is highest. The ‘lock and key’ model explains how the active site fits a specific substrate.
酶是加速代谢反应的生物催化剂。每种酶都有一个使其活性最高的最适温度和 pH。“锁钥模型”解释了活性位点如何与特定底物结合。
Enzyme activity is fastest at the optimum temperature and pH
酶活性在最适温度和 pH 下最快
As temperature rises, kinetic energy increases, and more enzyme-substrate complexes form. However, beyond the optimum, the active site denatures – its shape changes permanently – and the substrate can no longer bind. The graph below shows this pattern.
随着温度升高，动能增加，形成更多的酶-底物复合物。然而，超过最适温度后，活性位点会变性——其形状发生不可逆的改变——底物无法再结合。下图展示了这一模式。
| Condition (条件) | Effect on Enzyme (对酶的影响) |
|---|---|
| Low temperature (低温) | Low kinetic energy, fewer successful collisions, activity low (动能低，碰撞成功少，活性低) |
| Optimum temperature (最适温度) | Maximum rate of reaction, active sites fully occupied (反应速率最大，活性位点完全被占据) |
| High temperature (高温) | Denaturation, active site shape lost, reaction stops (变性，活性位点形状丧失，反应停止) |
| Extreme pH (极端 pH) | Denaturation by disrupting bonds in the active site (通过破坏活性位点中的化学键而变性) |
5. Rate of Diffusion and the Relationship with Surface Area | 扩散速率及其与表面积的关系
Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration. The rate at which this happens depends on three main factors: surface area, concentration gradient and diffusion distance.
扩散是粒子从高浓度区域向低浓度区域的净移动。这发生的速率取决于三个主要因素：表面积、浓度梯度和扩散距离。
Rate of diffusion ∝ (Surface area × Concentration difference) / Diffusion distance
扩散速率 ∝ (表面积 × 浓度差) / 扩散距离
This simplified relationship shows that a larger surface area, a steeper concentration gradient and a shorter diffusion distance all result in faster diffusion. In organisms, specialised exchange surfaces such as alveoli in the lungs and villi in the small intestine have large surface areas and thin membranes to maximise the rate of diffusion.
这个简化关系式表明，更大的表面积、更大的浓度梯度和更短的扩散距离都会使扩散更快。在生物体中，特殊的交换表面，如肺中的肺泡和小肠中的绒毛，都具有巨大的表面积和极薄的膜，以最大限度地提高扩散速率。
Oxygen diffuses from the alveoli into the blood because the concentration of oxygen is higher in the air sacs. Adaptations like a good blood supply maintain a steep concentration gradient.
氧气从肺泡扩散到血液中，是因为气囊中氧气的浓度更高。良好的血液供应等适应性特征能够维持一个陡峭的浓度梯度。
6. Osmosis and Water Potential Gradient | 渗透作用与水势梯度
Osmosis is a special case of diffusion that involves the movement of water molecules from a dilute solution (high water potential) to a more concentrated solution (low water potential) through a partially permeable membrane.
渗透作用是扩散的一种特例，涉及水分子通过半透膜从稀溶液（高水势）向较浓溶液（低水势）的移动。
Water moves from high water potential to low water potential
水从高水势区域向低水势区域移动
The direction of net movement is always down the water potential gradient. If an animal cell is placed in pure water, it may swell and burst because water enters by osmosis. In a concentrated salt solution, the cell shrinks as water leaves. Plant cells are protected by their cell wall and become turgid in dilute solutions or flaccid in concentrated ones.
净移动的方向总是沿着水势梯度向下。如果把一个动物细胞放入纯水中，由于水通过渗透作用进入，它可能会膨胀并破裂。在浓盐溶液中，细胞会因水流出而皱缩。植物细胞受到细胞壁的保护，在稀溶液中会变得坚挺（膨胀），在浓溶液中则会变得疲软（质壁分离）。
7. Energy Transfer Efficiency in Food Chains | 食物链中的能量传递效率
At each trophic level in a food chain, a large proportion of the energy stored in biomass is lost to the environment. The 10% rule is a useful approximation: only about one tenth of the energy available at one level is transferred to the next level.
在食物链的每个营养级中，贮存在生物量里的大部分能量都散失到环境中。“百分之十定律”是一个很有用的近似值：一个营养级上可利用的能量中只有大约十分之一能传递到下一营养级。
Energy transfer efficiency (%) = (Energy at higher level ÷ Energy at lower level) × 100
能量传递效率 (%) = (高营养级能量 ÷ 低营养级能量) × 100
Approximately 90% of energy is lost at each step through respiration, movement, heat production, excretion and undigested material. This loss of energy explains why food chains rarely have more than four or five trophic levels and why there are fewer top predators.
大约 90% 的能量在每一步中通过呼吸作用、运动、产热、排泄和未消化物质而损失。这种能量损失解释了为什么食物链很少超过四或五个营养级，以及为什么顶级捕食者的数量较少。
8. Genetic Ratios from Monohybrid Crosses | 单基因杂交的遗传比例
When you follow the inheritance of a single gene with two alleles, a monohybrid cross can be set up using a Punnett square. The most common pattern in Year 9 biology involves two heterozygous parents (e.g. Tt × Tt).
当你追踪由两个等位基因控制的单基因遗传时，可用庞纳特方格进行单基因杂交。Year 9 生物学中最常见的模式涉及两个杂合亲本（例如 Tt × Tt）。
Phenotypic ratio = 3 : 1 (dominant : recessive)
表型比例 = 3 : 1（显性 : 隐性）
Genotypic ratio = 1 : 2 : 1 (homozygous dominant : heterozygous : homozygous recessive)
基因型比例 = 1 : 2 : 1（纯合显性 : 杂合 : 纯合隐性）
The probability of an offspring showing the dominant trait is 3/4 (75%), while the chance of showing the recessive trait is 1/4 (25%). A Punnett square organises the possible allele combinations from each parent’s gametes.
后代表现出显性性状的概率是 3/4 (75%)，表现出隐性性状的概率是 1/4 (25%)。庞纳特方格将每个亲本配子可能的等位基因组合加以整理。
Probability = (Number of desired outcomes) / (Total number of outcomes)
概率 = 期望结果数 / 总结果数
9. Calculating Heart Rate from Pulse Measurements | 根据脉搏测量计算心率
Heart rate is the number of times your heart beats per minute (bpm). In a laboratory or fitness investigation, you can determine heart rate by counting the pulse for a set time and then scaling it to one minute.
心率是心脏每分钟搏动的次数（bpm）。在实验室或体能调查中，你可以通过数定长时间的脉搏，然后将其换算为一分钟来确定心率。
Heart rate (bpm) = Number of beats counted × (60 / time in seconds)
心率 (bpm) = 脉博次数 × (60 / 秒数)
For example, if you count 18 beats in 15 seconds, the heart rate is 18 × (60/15) = 18 × 4 = 72 bpm. This simple formula is vital for experiments linking exercise intensity to heart rate changes.
例如，如果你在 15 秒内数到 18 次搏动，心率就是 18 × (60/15) = 18 × 4 = 72 bpm。这个简单的公式对于将运动强度与心率变化联系起来的实验至关重要。
10. Biomass and Pyramids of Numbers | 生物量与数量金字塔
Biomass refers to the total dry mass of living material at a given trophic level. Pyramids of biomass are usually a better representation of an ecosystem than pyramids of numbers because they account for size differences among organisms.
生物量是指特定营养级上生物材料的总干质量。生物量金字塔通常比数量金字塔更能准确地表示一个生态系统，因为它考虑了生物体之间的大小差异。
Biomass at a trophic level = dry mass of all organisms at that level (g/m² or J)
某一营养级的生物量 = 该级所有生物体的干质量（克/平方米 或 焦耳）
A pyramid of biomass is almost always pyramid-shaped because energy losses limit the biomass that can be supported at higher levels. When drawing such pyramids, you must draw each bar to scale, with producers at the base and top consumers at the apex. The efficiency of biomass transfer can also be calculated using the same percentage formula used for energy transfer.
生物量金字塔几乎总是呈金字塔形状，因为能量损失限制了较高营养级所能支持的生物量。绘制此类金字塔时，你必须按比例绘制每个横条，以生产者作为底部，顶端消费者作为顶部。生物量传递效率也可以使用与能量传递相同的百分比公式进行计算。
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