📚 IGCSE Edexcel Biology: Respiration Key Points | IGCSE Edexcel 生物：呼吸作用 考点精讲
Respiration is a fundamental process that releases energy from food molecules to power all life activities. In IGCSE Edexcel Biology, you must understand the difference between aerobic and anaerobic respiration, the role of ATP, and how to describe and compare the word and chemical equations. This article breaks down every key point you need for the exam, with paired English–Chinese explanations to help bilingual learners master the topic.
呼吸作用是从食物分子中释放能量以驱动一切生命活动的基本过程。在 IGCSE Edexcel 生物课程中，你必须理解有氧呼吸与无氧呼吸的区别、ATP 的作用，并能描述和比较文字方程式与化学方程式。本文拆解了考试所需的每一个关键点，配以中英双语解释，帮助双语学习者掌握这一主题。
1. What is Respiration? | 什么是呼吸作用？
Respiration is the chemical process that happens inside every living cell to break down nutrient molecules (usually glucose) and release energy. It is not the same as breathing; breathing is the physical movement of air in and out of the lungs, while respiration is a series of enzyme‑controlled reactions inside cells.
呼吸作用是发生在每个活细胞内部的化学过程，分解营养分子（通常是葡萄糖）并释放能量。它与呼吸（换气）不同；呼吸是空气进出肺部的物理运动，而呼吸作用是细胞内由酶控制的一系列反应。
Respiration is exothermic, meaning it transfers energy to the surroundings, which is why warm‑blooded animals maintain a constant body temperature. The energy released is used for muscle contraction, active transport, cell division, maintaining body temperature, and building large molecules from smaller ones.
呼吸作用是放热反应，这意味着它将能量传递给周围环境，因此恒温动物能维持恒定体温。释放的能量用于肌肉收缩、主动运输、细胞分裂、维持体温以及从小分子构建大分子。
2. Aerobic Respiration Equation | 有氧呼吸方程式
Aerobic respiration uses oxygen to fully break down glucose into carbon dioxide and water, releasing a large amount of energy. The word equation is: glucose + oxygen → carbon dioxide + water (+ energy). The balanced chemical equation is:
有氧呼吸利用氧气将葡萄糖完全分解为二氧化碳和水，释放大量能量。文字方程式为：葡萄糖 + 氧气 → 二氧化碳 + 水（+ 能量）。配平的化学方程式如下：
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O (+ energy)
You must learn this equation exactly. One glucose molecule reacts with six oxygen molecules to produce six carbon dioxide molecules and six water molecules. The energy released is about 32 molecules of ATP per glucose molecule in ideal conditions.
你必须准确记忆这个方程式。一个葡萄糖分子与六个氧分子反应，生成六个二氧化碳分子和六个水分子。在理想条件下，每个葡萄糖分子释放的能量可产生约 32 个 ATP 分子。
In the exam, you may be asked to write the equation in words or symbols. Make sure you can balance it and identify the reactants and products. Also remember that the energy released is not a chemical substance but is transferred as ATP and heat.
考试中可能要求你用文字或符号写出方程式。确保你能配平并识别反应物和产物。还要记住，释放的能量不是化学物质，而是以 ATP 和热的形式转移。
3. Where Aerobic Respiration Occurs | 有氧呼吸发生场所
Aerobic respiration takes place mainly inside the mitochondria. These organelles have a double membrane; the inner membrane is highly folded into cristae, providing a large surface area for the enzymes involved in the later stages of respiration, such as the Krebs cycle and oxidative phosphorylation.
有氧呼吸主要发生在线粒体内部。这些细胞器具有双层膜；内膜高度折叠形成嵴，为呼吸作用后期阶段（如克雷布斯循环和氧化磷酸化）涉及的酶提供了巨大的表面积。
The first stage, glycolysis, occurs in the cytoplasm and does not require oxygen. Glycolysis splits one glucose molecule into two molecules of pyruvate, producing a small amount of ATP. The pyruvate then enters the mitochondria if oxygen is available for the subsequent aerobic stages.
第一阶段——糖酵解发生在细胞质中，不需要氧气。糖酵解将一个葡萄糖分子分解为两个丙酮酸分子，产生少量 ATP。如果有氧存在，丙酮酸随后进入线粒体进行后续的有氧阶段。
Cells that need a lot of energy, such as muscle cells and sperm cells, contain many mitochondria. You may be asked to relate structure to function: more mitochondria = higher rate of aerobic respiration.
需要大量能量的细胞，如肌细胞和精子细胞，含有许多线粒体。你可能会被要求建立结构与功能的联系：线粒体越多，有氧呼吸速率越高。
4. ATP – The Energy Currency | ATP——能量货币
ATP (adenosine triphosphate) is the immediate energy carrier in cells. The energy released during respiration is used to synthesise ATP from ADP and an inorganic phosphate (Pi). This reaction is reversible and catalysed by the enzyme ATP synthase.
ATP（三磷酸腺苷）是细胞内直接的能量载体。呼吸过程释放的能量用于由 ADP 和无机磷酸（Pi）合成 ATP。该反应可逆，由 ATP 合酶催化。
ADP + Pi (+ energy) ⇌ ATP + H₂O
When a cell needs energy, ATP is broken down back to ADP and Pi, releasing energy immediately for processes such as active transport, muscle contraction, and protein synthesis. Therefore, ATP acts as a rechargeable battery.
当细胞需要能量时，ATP 被分解回 ADP 和 Pi，即刻释放能量用于主动运输、肌肉收缩和蛋白质合成等过程。因此，ATP 就像一个可充电电池。
You do not need to describe the detailed mechanism of oxidative phosphorylation at IGCSE level, but you should understand that most ATP is produced in the mitochondria during aerobic respiration, and that without oxygen very little ATP is made.
在 IGCSE 水平，你不需要描述氧化磷酸化的详细机制，但应明白大多数 ATP 是在有氧呼吸过程中在线粒体内产生的，而没有氧气时只能制造极少量的 ATP。
5. Anaerobic Respiration in Humans | 人类的无氧呼吸
When oxygen supply is insufficient during vigorous exercise, muscle cells switch to anaerobic respiration. Glucose is partially broken down to release a small amount of energy without using oxygen. The word equation is: glucose → lactic acid (+ energy).
剧烈运动时供氧不足，肌细胞转为无氧呼吸。葡萄糖在不用氧的情况下部分分解，释放少量能量。文字方程式为：葡萄糖 → 乳酸（+ 能量）。
C₆H₁₂O₆ → 2C₃H₆O₃ (+ small amount of ATP)
Lactic acid builds up in muscles and causes cramp and fatigue. Once exercise stops, extra oxygen is taken in to oxidise the lactic acid back to carbon dioxide and water or convert it to glycogen. This extra oxygen is called the oxygen debt.
乳酸在肌肉中累积，导致抽筋和疲劳。运动停止后，人体会摄入额外氧气，将乳酸氧化回二氧化碳和水，或转化为糖原。这部分额外氧气称为氧债。
The energy yield of anaerobic respiration is only about 2 ATP per glucose molecule, compared to around 32 ATP in aerobic respiration. This is because glucose is only partially broken down; most of the energy remains locked in the lactic acid molecules.
无氧呼吸的能量产出仅为每个葡萄糖分子约 2 个 ATP，而有氧呼吸则约为 32 个 ATP。这是因为葡萄糖仅被部分分解，大部分能量仍锁在乳酸分子中。
6. Anaerobic Respiration in Yeast | 酵母菌的无氧呼吸
Yeast and some other microorganisms perform a different type of anaerobic respiration known as alcoholic fermentation. In the absence of oxygen, yeast converts glucose into ethanol and carbon dioxide, releasing a small amount of energy.
酵母菌和某些其他微生物进行一种不同的无氧呼吸，称为酒精发酵。在无氧条件下，酵母菌将葡萄糖转化为乙醇和二氧化碳，释放少量能量。
C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ (+ small amount of ATP)
This process is economically important for making bread and alcoholic beverages. The carbon dioxide released makes bread rise, while ethanol is the alcohol in beer and wine. At IGCSE, you must be able to write the word equation: glucose → ethanol + carbon dioxide (+ energy).
这一过程对制作面包和酒精饮料具有经济意义。释放的二氧化碳使面包膨胀，乙醇则是啤酒和葡萄酒中的酒精成分。在 IGCSE 中，你必须能够写出文字方程式：葡萄糖 → 乙醇 + 二氧化碳（+ 能量）。
Note that the ethanol produced by fermentation is toxic to yeast at high concentrations, so the reaction naturally stops when alcohol levels reach around 12–15%.
注意，发酵产生的乙醇在高浓度下对酵母菌有毒，因此当酒精浓度达到约 12–15% 时反应自然停止。
7. Comparing Aerobic and Anaerobic Respiration | 有氧呼吸与无氧呼吸的比较
The table below summarises the key differences that frequently appear in Edexcel IGCSE exams. Making precise comparisons will help you score full marks on extended‑response questions.
下表总结了 Edexcel IGCSE 考试中常出现的关键区别。进行精确比较将帮助你在拓展回应题上获得满分。
| Feature | 特征 | Aerobic Respiration | 有氧呼吸 | Anaerobic Respiration | 无氧呼吸 |
|---|---|---|
| Requires oxygen? | 是否需要氧气？ | Yes | 是 | No | 否 |
| Location | 发生部位 | Mitochondria (mainly) | 线粒体（主要） | Cytoplasm only | 仅细胞质 |
| Breakdown of glucose | 葡萄糖分解程度 | Complete | 完全 | Incomplete | 不完全 |
| Products | 产物 | CO₂ + H₂O | 二氧化碳 + 水 | Lactic acid (animals) or ethanol + CO₂ (yeast) | 乳酸（动物）或乙醇 + 二氧化碳（酵母） |
| ATP yield | ATP 产量 | High (~32 ATP per glucose) | 高（每葡萄糖约 32 ATP） | Low (~2 ATP per glucose) | 低（每葡萄糖约 2 ATP） |
| Need for mitochondria | 是否需要线粒体 | Yes | 是 | No | 否 |
A common misconception is that anaerobic respiration produces more energy quickly. In fact, it produces ATP much faster because it only involves glycolysis, but the total energy released per glucose is much lower. This is why you can sprint at maximum speed for only a short time.
一个常见的误解是，无氧呼吸快速产生更多能量。事实上，它产生 ATP 的速度确实更快，因为它仅涉及糖酵解，但每个葡萄糖释放的总能量却低得多。这就是为什么你只能短时间全力冲刺。
8. Investigating Respiration: Experiments | 探究呼吸作用：实验
Edexcel IGCSE often asks you to describe experiments that demonstrate the products or heat release of respiration. One common setup uses germinating seeds and a vacuum flask with a thermometer. The thermometer shows a temperature rise, proving respiration is exothermic.
Edexcel IGCSE 常要求你描述证明呼吸作用产物或放热的实验。一个常见装置使用正在萌发的种子和一个带温度计的保温瓶。温度计显示温度上升，证明呼吸作用放热。
To test for carbon dioxide production, germinating seeds can be placed in a sealed container with limewater or hydrogencarbonate indicator. The limewater turns milky, or the indicator turns from red/orange to yellow, showing increased CO₂ levels due to respiration.
为检验二氧化碳的产生，可将萌发的种子放入带石灰水或碳酸氢盐指示剂的密封容器中。石灰水变浑浊，或指示剂由红/橙色变为黄色，表明呼吸作用导致 CO₂ 浓度升高。
For controlled comparisons, you would set up a second container with boiled (dead) seeds to show that only living organisms produce the heat and CO₂. Always name the control and explain why it is needed.
为进行对照比较，你应设置另一套装有煮沸（死亡）种子的容器，以证明只有活生物体才能产生热量和二氧化碳。务必指出对照组并解释其必要性。
To investigate anaerobic respiration in yeast, use a test tube with glucose solution and yeast, covered with a layer of liquid paraffin to exclude oxygen. The production of CO₂ can be detected by connecting the tube to another containing limewater, which turns milky. The smell of ethanol can also be detected after a few days.
为探究酵母菌的无氧呼吸，使用装有葡萄糖溶液和酵母的试管，表面覆盖一层液体石蜡以隔绝氧气。产生的二氧化碳可通过连接另一支装有石灰水的试管来检测，石灰水变浑浊。几天后还可闻到乙醇的气味。
9. Factors Affecting the Rate of Respiration | 影响呼吸速率的因素
Like any enzyme‑controlled reaction, respiration rate is affected by temperature. As temperature rises, the kinetic energy of molecules increases, so the rate of respiration goes up – but only up to the optimum temperature (around 37°C in humans). Beyond this, enzymes denature and the rate falls sharply.
与任何酶控反应一样，呼吸速率受温度影响。随着温度升高，分子动能增加，因此呼吸速率上升——但仅到最适温度（人体约 37°C）为止。超过此温度，酶变性，速率急剧下降。
Glucose concentration also affects the rate. Higher glucose levels provide more substrate for respiration, up to the point where enzymes are saturated. You may see this presented in a graph where the rate plateaus.
葡萄糖浓度也会影响速率。在酶饱和之前，较高的葡萄糖水平为呼吸提供更多底物。你可能在图表中看到速率达到平台的现象。
Oxygen concentration is a limiting factor for aerobic respiration. Under low oxygen conditions, cells shift to anaerobic pathways. You should be able to interpret data showing that CO₂ production increases with oxygen availability up to a maximum.
氧气浓度是有氧呼吸的限制因素。在低氧条件下，细胞转为无氧途径。你应该能解读数据显示随着供氧增加，二氧化碳产生量增大至最大值。
Water availability is essential because many metabolic reactions occur in solution. Dehydrated cells have a much lower respiration rate. This links back to the need for water as a solvent and medium for biochemical reactions.
水分的可用性至关重要，因为许多代谢反应在溶液中进行。脱水的细胞呼吸速率显著降低。这与水作为生化反应溶剂和介质的需求相关。
10. Key Exam Tips and Summary | 考试关键提示与总结
Always define respiration as a chemical process that releases energy, not as breathing. Use precise wording: ‘aerobic respiration requires oxygen and produces carbon dioxide and water’, while ‘anaerobic respiration does not require oxygen and produces lactic acid (in animals) or ethanol and carbon dioxide (in yeast)’.
始终将呼吸作用定义为释放能量的化学过程，而非呼吸（换气）。使用精确措辞：“有氧呼吸需要氧气，产生二氧化碳和水”，而“无氧呼吸不需要氧气，产生乳酸（动物）或乙醇和二氧化碳（酵母）”。
When writing equations, check that you have balanced the number of atoms and have not confused the products. Remember that the energy released is not a chemical product but is transferred as ATP. Practice drawing and labeling a mitochondrion, as structure‑related questions are common.
书写方程式时，检查原子数是否配平，不要混淆产物。记住释放的能量不是化学产物，而是以 ATP 的形式转移。练习绘制并标注线粒体，因为与结构相关的问题很常见。
For experimental questions, always include a control, identify independent and dependent variables, and state a clear conclusion based on the trend. Use keywords like ‘exothermic’, ‘denatured’, ‘oxygen debt’, and ‘fermentation’ to show your understanding.
对于实验类问题，务必设置对照组，确定自变量和因变量，并基于趋势给出清晰结论。使用“放热”、“变性”、“氧债”和“发酵”等关键词来展示你的理解。
Finally, link respiration to other topics: digestion provides the glucose, the circulatory system delivers oxygen and removes waste, and the nervous and muscular systems use the ATP. Edexcel IGCSE rewards these cross‑topic connections.
最后，将呼吸作用与其他主题联系起来：消化系统提供葡萄糖，循环系统输送氧气并带走废物，神经和肌肉系统消耗 ATP。Edexcel IGCSE 鼓励这种跨主题的联系。
Published by TutorHao | Biology Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
屏轩国际教育cambridge primary/secondary checkpoint, cat4, ukiset,ukcat,igcse,alevel,PAT,STEP,MAT, ibdp,ap,ssat,sat,sat2课程辅导，国外大学本科硕士研究生博士课程论文辅导