📚 Year 10 CIE Science: Common Misconceptions and How to Correct Them | 十年级CIE科学：常见误区与纠正方法
In Year 10 CIE Science, students frequently encounter conceptual blocks that can turn into long‑term misunderstandings. Across Biology, Chemistry and Physics, certain ideas 'feel' right but contradict the scientific model. This article collects ten of the most persistent misconceptions, explains why they are wrong, and gives the correct explanations that align with the Cambridge IGCSE syllabus. Reading them carefully will help you avoid common traps in exams and build a more accurate mental picture of how the world works.
在十年级 CIE 科学课程中，学生常常会碰到一些概念障碍，若不及时纠正，就容易变成长期的误解。在生物、化学和物理三个学科中都存在着某些“听起来合理”却违背科学模型的观念。本文整理了十个最常见的顽固误区，解释它们错在哪里，并给出符合剑桥 IGCSE 大纲的正确表述。仔细阅读这些内容，能帮助你在考试中避开常见陷阱，并建立一个更准确的对自然世界的理解。
1. Plants Get Their Food from the Soil | 植物从土壤中获得食物
A very widespread idea is that plants extract their 'food' directly from the soil through their roots. In truth, plants are autotrophs: they manufacture their own organic nutrients, primarily glucose, using the process of photosynthesis. The raw materials for photosynthesis are carbon dioxide (from the air) and water (largely from the soil). Soil also supplies mineral ions such as nitrate and magnesium, which are essential for making proteins and chlorophyll, but these are not the plant's energy source. The glucose produced is either used in respiration or converted into starch, cellulose or other molecules.
一个非常普遍的想法是：植物通过根部从土壤中直接吸收“食物”。事实上，植物是自养生物：它们利用光合作用自己制造有机营养，主要是葡萄糖。光合作用的原料是二氧化碳（来自空气）和水（主要来自土壤）。土壤还提供硝酸盐和镁等矿质离子，对合成蛋白质和叶绿素至关重要，但它们并不是植物的能量来源。产生的葡萄糖要么用于呼吸作用，要么转化为淀粉、纤维素或其他分子。
2. Heavier Objects Fall Faster Than Light Objects | 较重的物体比轻的物体下落得更快
Many learners expect a bowling ball to hit the ground before a tennis ball when dropped from the same height. In the absence of air resistance, all objects fall with the same constant acceleration of roughly 9.8 m/s², regardless of their mass. This was famously demonstrated by Galileo and later by the Apollo 15 feather‑and‑hammer experiment on the Moon. On Earth, air resistance can cause lighter or larger‑surface‑area objects to fall more slowly, but that is a separate force acting against gravity, not a property of weight. The key point is that gravitational acceleration is independent of mass.
很多学习者认为，从同一高度同时抛下一个保龄球和一个网球，保龄球会先落地。在没有空气阻力的情况下，所有物体都以大约 9.8 m/s² 的恒定加速度下落，与质量无关。伽利略的思辨实验以及后来阿波罗 15 号在月球上进行的羽毛和锤子实验都精彩地证明了这一点。在地球上，空气阻力可能使较轻或表面积较大的物体下落变慢，但那是与重力方向相反的独立的力，并非重量本身的属性。关键是重力加速度与质量无关。
3. Electric Current Gets 'Used Up' in a Circuit | 电流在电路中被“用完”
A classic circuit misconception is that the electric current leaving the battery is somehow diminished after passing through a bulb or resistor. In a simple series circuit, the current is the same at all points. The charged particles (electrons) are already present throughout the conducting loop, and the battery provides the energy to push them around. What gets 'used up' or, more accurately, transferred, is energy. The bulb converts electrical energy into light and heat, but the number of charges flowing per second (current) remains constant. If current were used up, the flow would stop, and the bulb would not light continuously.
一个关于电路的经典误区是：流过电池的电流在经过灯泡或电阻后会被减弱。在简单的串联电路中，各处的电流大小是相同的。带电粒子（电子）本来就存在于整个导电回路中，电池提供能量推动它们流动。真正被“消耗”或者说被转化的，是能量。灯泡把电能转化为光和热，但每秒流过某一横截面的电荷数（电流）保持不变。如果电流真的被用掉了，流动就会停止，灯泡也就无法持续发光。
4. Burning Is a Physical Change | 燃烧是物理变化
Because wood seems to 'disappear' into ash and smoke, some students classify burning as a physical change akin to melting or evaporation. Burning (combustion) is a chemical reaction: a fuel reacts with oxygen to produce new substances, typically carbon dioxide and water vapour. In the case of hydrocarbons or carbohydrates, the reaction is irreversible under ordinary conditions. Chemical bonds are broken and new bonds formed, which is the hallmark of a chemical change. Moreover, the release of heat and light further confirms that new products with lower chemical potential energy have been created.
因为木材似乎“消失”成了灰烬和烟雾，有些学生便以为燃烧是类似于熔化或蒸发的物理变化。然而，燃烧（氧化反应）是一种化学变化：燃料与氧气反应，生成新的物质，通常是二氧化碳和水蒸气。对于碳氢化合物或碳水化合物，该反应在通常条件下不可逆。化学键断裂并形成新的化学键，这正是化学变化的标志。此外，热和光的释放也进一步表明，产生了化学势能更低的新产物。
5. Temperature Keeps Rising During Melting and Boiling | 熔化和沸腾过程中温度持续升高
When heating ice, students often assume the temperature climbs steadily all the way to boiling. A heating curve reveals a different picture: while a substance is changing state (e.g., melting at 0 °C or boiling at 100 °C for pure water at standard pressure), the temperature remains constant even though energy is continuously being supplied. This supplied energy is used to overcome the attractive forces between particles rather than to raise their average kinetic energy. That 'hidden' energy is called latent heat. The temperature only resumes its climb once the phase transition is complete.
在加热冰块时，学生常常假设温度会稳步上升到沸腾。加热曲线展示了不同的情景：当物质处于状态变化中时（例如纯水在标准压力下于 0 °C 熔化或 100 °C 沸腾），温度保持不变，尽管能量在持续输入。这部分输入的能量用于克服粒子间的吸引力，而不是增加其平均动能。这种“隐藏”的能量叫做潜热。只有当相变完成后，温度才会重新开始上升。
6. 'Natural' Means Safe and 'Synthetic' Means Dangerous | “天然的”就是安全的，“合成的”就是危险的
There is a common belief that chemicals derived from nature are inherently harmless while those made in laboratories are harmful. Science teaches us that toxicity depends on the structure and dose of a substance, not its origin. Many natural compounds are acutely toxic: cyanide from bitter almonds, hemlock poison, and ricin from castor beans are all natural. Conversely, synthetic polymers have produced life‑saving medical devices. Risk assessment in chemistry focuses on empirical evidence, not on whether a substance occurs in nature.
有一种普遍的看法是：从自然界提取的化学物质天然无害，而实验室合成的物质才会有害。科学告诉我们，毒性取决于物质的结构和剂量，而非其来源。许多天然化合物的毒性很强：苦杏仁中的氰化物、毒芹毒素、蓖麻子中的蓖麻毒素都是天然的。相反，合成聚合物却制造出了救命的医疗器械。化学中的风险评估依据的是实验证据，而不是某物质是否在自然界存在。
7. The Heart Lies Entirely on the Left Side of the Chest | 心脏完全在胸腔左侧
Textbook diagrams often show the heart shifted to the left, leading many students to believe it is positioned almost completely on the left side of the body. In reality, the heart is located in the centre of the chest behind the sternum, inside a cavity called the mediastinum. It is tilted so that its apex points slightly to the left, which creates the sensation of a stronger heartbeat on the left. However, a large portion of the heart mass—including the right atrium and right ventricle—lies either centrally or slightly to the right of the midline.
教科书插图常将心脏画得偏左，导致许多学生认为它几乎完全位于身体左侧。实际上，心脏位于胸腔中央，在胸骨后面一个叫作纵隔的腔隙内。它的位置向左倾斜，心尖指向左下方，因而左侧的心跳感觉更强。但心脏的很大一部分，包括右心房和右心室，都在中线位置或略微偏右。
8. All Bacteria Are Harmful Germs | 所有细菌都是有害的病菌
The 'germ theory' education sometimes leaves students with the impression that bacteria are universally dangerous. While pathogenic bacteria do cause diseases such as cholera and tuberculosis, the vast majority of bacterial species are harmless or even essential to life. Nitrogen‑fixing bacteria in the soil convert atmospheric nitrogen into forms plants can use. Bacteria in the human gut synthesise vitamins (e.g., vitamin K) and help digest food. Decomposer bacteria recycle nutrients in ecosystems. Without bacteria, dead organic matter would accumulate and global nutrient cycles would break down.
“细菌致病”的教学有时会让学生产生一种印象：所有细菌都是危险的。虽然致病性细菌确实会引起霍乱、结核病等疾病，但绝大多数细菌物种是无害的，甚至对生命至关重要。土壤中的固氮细菌能将大气中的氮转化为植物可利用的形式。人体肠道内的细菌合成维生素（如维生素K）并帮助消化食物。分解细菌则在生态系统中回收养分。如果没有细菌，死亡的有机质就会堆积，全球养分循环将崩溃。
9. Energy Can Be 'Used Up' or Destroyed | 能量会被“用完”或消灭
In everyday language we say a battery 'runs out of energy' or a torch 'uses up' energy. This phrasing can implant the false idea that energy disappears. The principle of conservation of energy states that energy cannot be created or destroyed, only converted from one form to another. A battery converts chemical energy into electrical energy, which is then changed into light and heat in the bulb. The total quantity of energy remains the same; it merely becomes more dissipated into the surroundings, making it less available to do useful work. What is depleted is the store of chemical potential energy in the battery, not energy itself.
在日常语言中，我们会说电池“没电了”或者手电筒“耗尽了”能量。这种说法可能植入一种错误观念，即能量消失了。能量守恒定律指出，能量既不能创造也不能消灭，只能从一种形式转化为另一种形式。电池将化学能转化为电能，电能又在灯泡中转化为光和热。能量的总量保持不变，只是更多地散逸到周围环境中，变得不易用来做有用功。耗尽的是电池内储存的化学势能，而不是能量本身。
10. Summers Are Caused by Earth Being Closer to the Sun | 夏天是由地球离太阳更近引起的
Because many people feel hotter when they physically move closer to a fire, they assume the same logic explains the seasons. If proximity to the Sun were the main cause, the whole planet would experience summer at the same time. In reality, Earth's orbit is only slightly elliptical, and the distance change is too small to drive the large temperature swings we observe. Seasons are caused by the 23.5° tilt of Earth's axis relative to its orbital plane. This tilt changes the angle at which sunlight strikes the surface and the duration of daylight, concentrating solar energy in one hemisphere while the other cools.
由于人们靠近火源时会感觉更热，许多人就以为季节也是同样的原理。如果与太阳的距离是主因，那么整个地球应该同时经历夏季。实际上，地球的轨道只是微椭圆，距离的变化太小，不足以引起我们观察到的大幅温度变化。季节是由地轴相对于轨道平面倾斜约 23.5° 造成的。这种倾斜改变了阳光照射地表的倾角和白昼长度，使一个半球获得的太阳能量更集中，而另一个半球则在降温。
11. Pure Water Is a Good Conductor of Electricity | 纯水是电的良导体
Movies and safety warnings often show a person being electrocuted through water, which leads students to think water itself conducts electricity well. Chemically pure water is actually a very poor conductor because it contains almost no free ions. The conductivity of tap water or natural water bodies comes from dissolved ionic compounds—such as sodium chloride, calcium bicarbonate, and various salts—that dissociate into mobile charge carriers. It is these dissolved ions, not the H₂O molecules, that allow a current to pass. When dealing with electrical safety, it is the presence of impurities that makes water dangerous.
电影和用电安全警示中经常出现人通过水触电的场景，这让学生以为水本身极易导电。实际上，化学纯的水是极差的导体，因为它几乎不含自由离子。自来水或天然水体之所以导电，是因为溶解了离子化合物——如氯化钠、碳酸氢钙和各种盐类——它们离解成可自由移动的电荷载体。是这些溶解的离子，而非水分子本身允许电流通过。在用电安全方面，正是这些杂质的存在让水变得危险。
12. Respiration Is the Same as Breathing | 呼吸就是呼气和吸气
In everyday language 'respiration' is often used interchangeably with 'breathing', but in Biology they are distinct processes. Breathing (ventilation) is the physical movement of air into and out of the lungs, driven by the diaphragm and intercostal muscles. Respiration is a chemical process that takes place inside every living cell. It is the controlled release of energy from glucose, typically using oxygen to produce ATP, carbon dioxide and water. The two are connected—breathing supplies the oxygen needed for aerobic respiration and removes the waste carbon dioxide—but confusing them can lead to serious errors when explaining gas exchange, exercise physiology or energy flow.
在日常用语中，“呼吸”与“细胞呼吸”常被混用，但在生物学中它们是两个截然不同的过程。呼吸（通气）是指空气在肺中的进出，由膈肌和肋间肌驱动的物理运动。细胞呼吸则是在每一个活细胞内部发生的化学过程，是从葡萄糖中有控制地释放能量，通常利用氧气产生 ATP、二氧化碳和水。两者是相互关联的——呼吸运动为有氧呼吸提供所需的氧气并排出代谢产生的二氧化碳——但若将它们混淆，在解释气体交换、运动生理或能量流动时会产生严重错误。
Published by TutorHao | Science Revision Series | aleveler.com
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