📚 Year 10 CAIE Biology: Core Knowledge Summary | Year 10 CAIE 生物：核心知识点梳理
Year 10 CAIE Biology provides the foundation for understanding life processes, from the molecular level to ecosystems. This revision summary distills the core topics examined in the CAIE syllabus, including cell biology, transport, enzymes, nutrition, and ecology. Mastering these key concepts will help you excel in assessments and build a solid base for further study.
10 年级 CAIE 生物课程为理解从分子到生态系统的生命过程奠定基础。本复习梳理提炼了 CAIE 大纲中考察的核心主题，涵盖细胞生物学、物质运输、酶、营养和生态学。掌握这些关键概念将帮助你在考核中脱颖而出，并为继续学习打下坚实基础。
1. Cell Structure and Function | 细胞结构与功能
All living organisms are made of cells. Animal cells typically contain a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. Plant cells have these same structures plus a rigid cell wall, a large permanent vacuole and chloroplasts.
所有生物体都由细胞构成。动物细胞通常包含细胞核、细胞质、细胞膜、线粒体和核糖体。植物细胞除了具有这些结构外，还有坚硬的细胞壁、一个中央大液泡和叶绿体。
The nucleus controls cell activities and stores genetic material (DNA). Mitochondria are the sites of aerobic respiration, releasing energy for the cell. Ribosomes synthesise proteins. The cell membrane controls what enters and exits the cell. In plants, chloroplasts absorb light for photosynthesis, and the vacuole stores sap and maintains turgor pressure.
细胞核控制细胞活动并储存遗传物质（DNA）。线粒体是有氧呼吸的场所，为细胞释放能量。核糖体合成蛋白质。细胞膜控制物质进出细胞。在植物中，叶绿体吸收光能进行光合作用，液泡储存细胞液并维持膨压。
2. Movement of Substances | 物质进出细胞
Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration down a concentration gradient. It is a passive process that requires no energy. Examples include oxygen diffusing into blood in the lungs and carbon dioxide diffusing out of leaf cells.
扩散是粒子沿浓度梯度从高浓度区域向低浓度区域的净移动，是一种不需要能量的被动过程。例子包括氧气在肺部扩散进入血液，以及二氧化碳从叶肉细胞扩散出去。
Osmosis is the net movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane. In plant cells, water entering by osmosis makes the cell turgid; in animal cells, too much water intake can cause lysis (bursting).
渗透是水分子通过半透膜，从水势较高的区域向水势较低区域的净移动。在植物细胞中，水分通过渗透进入会使细胞变得硬挺；在动物细胞中，摄入过多水分可能导致细胞胀破（裂解）。
Active transport moves substances against a concentration gradient, from low to high concentration, using energy from respiration. Carrier proteins in the membrane pump specific molecules, such as mineral ions into root hair cells or glucose into intestinal villi.
主动运输逆浓度梯度，使物质从低浓度向高浓度移动，需要呼吸作用提供的能量。膜上的载体蛋白泵出特定分子，例如矿物质离子进入根毛细胞，或葡萄糖进入小肠绒毛细胞。
3. Biological Molecules and Food Tests | 生物分子与食物检测
The main biological molecules are carbohydrates, proteins and lipids (fats). Carbohydrates include simple sugars like glucose, and complex polymers like starch and cellulose. Proteins are made of amino acids, and lipids are composed of fatty acids and glycerol.
主要生物分子包括碳水化合物、蛋白质和脂质（脂肪）。碳水化合物包含葡萄糖等单糖，以及淀粉和纤维素等复杂聚合物。蛋白质由氨基酸构成，脂质由脂肪酸和甘油组成。
To identify nutrients, standard food tests are used. The table below summarises the key tests required in the CAIE syllabus.
鉴定营养物质需要使用标准的食物检测方法。下表总结了 CAIE 大纲中要求掌握的关键检测。
| Test for | Reagent | Method | Positive result |
|---|---|---|---|
| Reducing sugars | Benedict’s solution | Heat in water bath | Blue → brick-red precipitate |
| Starch | Iodine solution | Add few drops | Yellow-brown → blue-black |
| Protein | Biuret reagent | Add and shake | Blue → violet/purple |
| Lipids | Ethanol | Dissolve in ethanol, then pour into water | Cloudy white emulsion |
Benedict’s test detects reducing sugars (e.g. glucose); the colour change goes from blue to green, yellow and finally brick-red depending on the concentration. The biuret test requires sodium hydroxide and copper sulfate to detect peptide bonds in proteins.
本尼迪克特检测法检测还原糖（如葡萄糖）；颜色根据浓度由蓝变绿、黄到砖红色。双缩脲检测使用氢氧化钠和硫酸铜来检测蛋白质中的肽键。
4. Enzymes | 酶
Enzymes are biological catalysts made of protein that speed up chemical reactions without being consumed. Each enzyme has an active site that is complementary in shape to its specific substrate – this is known as the lock-and-key model. The substrate fits into the active site, forming an enzyme-substrate complex, and products are released, leaving the enzyme unchanged.
酶是由蛋白质构成的生物催化剂，能加速化学反应而本身不被消耗。每种酶都有一个活性位点，其形状与特定底物互补——这被称为锁钥模型。底物进入活性位点形成酶-底物复合物，产物释放后酶保持不变。
Enzyme activity is affected by temperature and pH. As temperature rises, activity increases until an optimum (often around 37°C in humans) is reached; beyond that, the enzyme denatures – its active site loses shape and can no longer bind the substrate. Each enzyme also has an optimum pH, and extremes of pH cause denaturation.
酶的活性受温度和 pH 的影响。温度升高时活性增加，达到最适温度（人体中约为 37°C）后，进一步升温会使酶变性——活性位点失去形状，无法再与底物结合。每种酶也有最适 pH，极端的 pH 会导致变性。
A common practical investigation uses amylase and starch at different temperatures or pH values, measuring the time for starch to be broken down (tested with iodine). This demonstrates the effect of conditions on enzymatic rate.
常见的实验研究使用淀粉酶和淀粉在不同温度或 pH 下反应，测量淀粉被分解完所需时间（用碘液检测）。这展示了环境条件对酶促反应速率的影响。
5. Plant Nutrition and Photosynthesis | 植物营养与光合作用
Photosynthesis is the process by which green plants manufacture glucose from carbon dioxide and water using light energy absorbed by chlorophyll. The overall word equation is:
光合作用是绿色植物利用叶绿素吸收的光能，将二氧化碳和水转化为葡萄糖的过程。总的文字方程式为：
Carbon dioxide + Water → Glucose + Oxygen
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
The leaf is adapted for photosynthesis: broad, flat lamina to capture light; thin structure for short diffusion distance; stomata for gas exchange; and numerous chloroplasts concentrated in palisade mesophyll cells.
叶片适应光合作用：宽而扁平的叶片以捕捉光；薄的结构缩短扩散距离；气孔进行气体交换；大量的叶绿体集中在栅栏组织细胞中。
Limiting factors include light intensity, carbon dioxide concentration and temperature. At low light, the rate of photosynthesis is limited by light; once it becomes saturating, another factor may become limiting. Mineral deficiencies also affect growth – lack of nitrate ions causes stunted growth because proteins cannot be made; lack of magnesium leads to chlorosis (yellowing) because chlorophyll cannot be synthesised.
限制因素包括光照强度、二氧化碳浓度和温度。在弱光下，光合作用速率受光限制；当光达到饱和，另一个因素可能成为限制。矿物质缺乏也影响生长——缺硝酸根离子会导致植株矮小，因为无法合成蛋白质；缺镁会导致褪绿（叶片发黄），因为叶绿素无法合成。
6. Transport in Plants | 植物运输
Plants have two transport tissues: xylem and phloem. Xylem vessels transport water and dissolved mineral ions from roots to leaves. Xylem cells are dead, hollow tubes strengthened by lignin, allowing water to flow upward in one direction.
植物有两种运输组织：木质部和韧皮部。木质部导管将水和溶解的矿物质离子从根部运输到叶片。木质部细胞是死细胞，中空，由木质素加固，使水单向向上流动。
Phloem transports sucrose and amino acids from sources (e.g. leaves) to sinks (e.g. growing roots) in a process called translocation. Phloem consists of living sieve tubes and companion cells.
韧皮部将蔗糖和氨基酸从源（如叶片）运输到库（如生长的根），这个过程称为转运。韧皮部由活的筛管和伴胞组成。
Transpiration is the evaporation of water from leaf surfaces, mainly through stomata. It creates a pull (transpiration stream) that draws water up the xylem. Factors that increase transpiration rate include higher temperature, increased wind speed, higher light intensity (stomata open wider) and lower humidity.
蒸腾作用是水分从叶片表面（主要是气孔）蒸发的过程。它产生一种拉力（蒸腾流）将水拉上木质部。提高蒸腾速率的因素包括温度升高、风速加大、光照增强（气孔开得更大）和湿度降低。
7. Human Nutrition and Diet | 人体营养与饮食
A balanced diet includes carbohydrates, proteins, lipids, vitamins, minerals, dietary fibre and water. Each component has a specific role: carbohydrates provide energy; proteins supply amino acids for growth and repair; lipids form cell membranes and provide insulation; vitamins and minerals aid various functions, and fibre prevents constipation.
均衡饮食包括碳水化合物、蛋白质、脂质、维生素、矿物质、膳食纤维和水。每种成分都有特定的作用：碳水化合物提供能量；蛋白质提供氨基酸用于生长和修复；脂质构成细胞膜并提供隔热；维生素和矿物质辅助多种功能，纤维预防便秘。
Deficiency diseases arise from lacking essential nutrients. Vitamin C deficiency causes scurvy (bleeding gums), vitamin D deficiency leads to rickets (soft bones in children), and iron deficiency results in anaemia (fewer red blood cells, fatigue).
缺乏必需营养素会导致缺乏病。维生素 C 缺乏引起坏血病（牙龈出血），维生素 D 缺乏导致佝偻病（儿童骨骼软化），铁缺乏导致贫血（红细胞减少，疲劳）。
The digestive system breaks down large insoluble molecules into small soluble ones that can be absorbed. Mechanical digestion (chewing) and chemical digestion (enzymes) occur. Amylase breaks down starch into maltose; proteases break proteins into amino acids; lipases break lipids into fatty acids and glycerol. Absorption of these small molecules takes place mainly in the small intestine, which is lined with villi and microvilli to increase surface area.
消化系统将大分子不溶物质分解成小分子可溶物质以被吸收。机械消化（咀嚼）和化学消化（酶）同时发生。淀粉酶将淀粉分解为麦芽糖；蛋白酶将蛋白质分解为氨基酸；脂肪酶将脂质分解为脂肪酸和甘油。这些小分子主要在小肠吸收，小肠内壁布满绒毛和微绒毛以增加表面积。
8. Transport in Humans: The Circulatory System | 人体运输：循环系统
The human circulatory system consists of the heart, blood vessels and blood. The heart is a muscular organ with four chambers: two atria and two ventricles. Valves prevent backflow of blood. The right side pumps deoxygenated blood to the lungs (pulmonary circulation), and the left side pumps oxygenated blood to the rest of the body (systemic circulation) – a double circulatory system.
人体循环系统由心脏、血管和血液组成。心脏是一个肌肉发达的四腔器官：两个心房和两个心室。瓣膜防止血液倒流。右侧将去氧血泵送到肺部（肺循环），左侧将含氧血泵送到全身其他部位（体循环）——这是一个双循环系统。
Three types of blood vessels are involved. Arteries carry blood away from the heart; they have thick muscular and elastic walls to withstand high pressure. Veins return blood to the heart; they have thinner walls and contain valves. Capillaries are microscopic, one-cell-thick vessels where exchange of gases, nutrients and wastes occurs.
涉及三种类型的血管。动脉将血液从心脏运出；它们壁厚，富有肌肉和弹性，以承受高压。静脉将血液运回心脏；它们壁较薄且有瓣膜。毛细血管是仅一个细胞厚的微小血管，发生气体、营养物质和废物的交换。
Blood is composed of plasma, red blood cells (erythrocytes), white blood cells (leucocytes) and platelets. Plasma transports dissolved substances such as carbon dioxide, glucose, and hormones. Red blood cells contain haemoglobin which binds oxygen for transport. White cells defend against infection, and platelets help clot blood.
血液由血浆、红细胞、白细胞和血小板组成。血浆运输溶解的物质，如二氧化碳、葡萄糖和激素。红细胞含有血红蛋白，可结合氧气进行运输。白细胞防御感染，血小板帮助血液凝固。
9. Respiration | 呼吸作用
Respiration is the release of energy from glucose in living cells. It is not the same as breathing. Aerobic respiration uses oxygen and yields a large amount of energy. The balanced symbol equation is:
呼吸作用是活细胞从葡萄糖中释放能量的过程，与呼吸（通气）不同。有氧呼吸消耗氧气，产生大量能量。配平的符号方程式为：
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O (+ energy)
Anaerobic respiration occurs when oxygen is insufficient. In yeast and some plants, it produces ethanol and carbon dioxide:
当氧气不足时，发生无氧呼吸。在酵母和某些植物中，会产生乙醇和二氧化碳：
Glucose → Ethanol + Carbon dioxide (+ some energy)
C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂
In human muscles during vigorous exercise, anaerobic respiration produces lactic acid, which can cause muscle cramps and fatigue. The energy yield is much lower than aerobic respiration.
在人体肌肉剧烈运动时，无氧呼吸产生乳酸，可能导致肌肉酸痛和疲劳。其能量产量远低于有氧呼吸。
Common experiments to investigate respiration often use germinating seeds. They absorb oxygen and release carbon dioxide (shown by hydrogencarbonate indicator turning yellow) and release heat (temperature rise in a vacuum flask).
研究呼吸作用的常见实验常利用萌发种子。它们吸收氧气并释放二氧化碳（表现为碳酸氢盐指示剂变黄），同时释放热量（保温瓶中温度上升）。
10. Ecology and Ecosystems | 生态与生态系统
An ecosystem consists of a community of organisms interacting with their physical environment. Food chains show the flow of energy from producers (plants) to primary consumers (herbivores) and up to secondary and tertiary consumers (carnivores). A food web is a network of interconnected food chains.
生态系统由生物群落与其物理环境相互作用构成。食物链展示能量从生产者（植物）到初级消费者（植食动物）再到次级和三级消费者（肉食动物）的流动。食物网是相互连接的食物链网络。
Energy is lost at each trophic level through movement, heat, respiration and uneaten parts. Typically, only about 10% of energy is passed on, which limits the length of food chains. Pyramids of biomass represent the dry mass of living material at each level and are usually pyramid-shaped, reflecting energy loss.
能量在每个营养级中因运动、热量、呼吸作用和未食部分而损失。通常仅约 10% 的能量传递，这限制了食物链的长度。生物量金字塔表示各层次生物的干重，通常呈金字塔形，反映了能量的损失。
The carbon cycle is essential for recycling carbon. Carbon dioxide in the atmosphere is removed by photosynthesis and returned by respiration, decomposition and combustion. Fossil fuels formed from ancient organisms release CO₂ when burned, contributing to enhanced greenhouse effect.
碳循环对碳的回收至关重要。大气中的二氧化碳通过光合作用被移除，并通过呼吸作用、分解和燃烧返回。来自古代生物的化石燃料燃烧时释放 CO₂，加剧温室效应。
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