Mastering Environmental Science for IGCSE WJEC Science: Key Concepts and Exam Tips | IGCSE WJEC 科学：环境科学考点精讲

📚 Mastering Environmental Science for IGCSE WJEC Science: Key Concepts and Exam Tips | IGCSE WJEC 科学：环境科学考点精讲

Environmental Science forms a crucial part of the IGCSE WJEC Science syllabus, integrating biology, chemistry, and physics to understand the natural world and the impact of human activities. This comprehensive revision guide covers the essential topics, from ecosystems to sustainability, and provides exam-focused strategies to help you succeed. Whether you’re tackling the Double Award or separate sciences, mastering these concepts will boost your confidence and your grade.

环境科学是 IGCSE WJEC 科学大纲的重要组成部分，融合了生物、化学和物理知识，帮助我们理解自然界以及人类活动的影响。这份全面的复习指南涵盖了从生态系统到可持续发展的所有重要主题，并提供以应试为导向的策略，助你成功。无论你参加双科学还是单独科学考试，掌握这些概念都将提升你的信心和成绩。

1. Ecosystems and Habitats | 生态系统与栖息地

An ecosystem is a community of living organisms (biotic factors) interacting with their non-living environment (abiotic factors) such as temperature, water, and sunlight. Habitat refers to the specific place where an organism lives. Within an ecosystem, populations of different species form a community, and their interactions include predation, competition, and symbiosis.

生态系统是生物群落（生物因素）与其非生物环境（非生物因素，如温度、水和阳光）相互作用的一个整体。栖息地是指生物体生活的特定地点。在生态系统中，不同物种的种群形成群落，它们之间的相互作用包括捕食、竞争和共生。

Key terms: A population is a group of individuals of the same species living in the same area. A niche describes an organism’s role in the ecosystem, including its habitat, feeding relationships, and interactions. Understanding these levels—individual, population, community, ecosystem—forms the basis of ecology.

关键术语：种群是生活在同一地区的同一物种个体组成的群体。生态位描述生物在生态系统中的角色，包括其栖息地、摄食关系和相互作用。理解这些层次——个体、种群、群落、生态系统——是生态学的基础。

WJEC exam questions often ask you to define these terms and apply them to a named example, such as a woodland or pond ecosystem. Be precise: ‘habitat’ is not the same as ‘ecosystem’.

WJEC 考题常要求定义这些术语，并将其应用于具体实例，如林地或池塘生态系统。务必准确：“栖息地”不同于“生态系统”。

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2. Energy Flow and Food Chains | 能量流动与食物链

Energy enters most ecosystems as sunlight and is captured by producers (plants) through photosynthesis. The general equation for photosynthesis is: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. This chemical energy is then transferred through feeding relationships in food chains and food webs.

能量以阳光形式进入大多数生态系统，被生产者（植物）通过光合作用捕获。光合作用的总方程式为：6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂。这种化学能随后通过食物链和食物网中的摄食关系传递。

A food chain shows the linear sequence of who eats whom: e.g., grass → grasshopper → frog → snake → hawk. Arrows indicate the direction of energy flow. At each trophic level, energy is lost through respiration, movement, and heat; only about 10% is passed on to the next level. This limits the length of food chains.

食物链显示谁吃谁的线性顺序，例如：草 → 蚱蜢 → 青蛙 → 蛇 → 鹰。箭头表示能量流动的方向。在每个营养级，能量通过呼吸作用、运动、散热等消耗，只有约10%传递到下一个营养级。这限制了食物链的长度。

You may be asked to construct or interpret pyramid diagrams. A pyramid of biomass represents the dry mass of living material at each trophic level and is usually upright. A pyramid of energy is always upright and shows energy content. Use these to explain why there are fewer top predators.

你可能会被要求绘制或解释金字塔图。生物量金字塔表示每个营养级的生物干重，通常呈直立形状。能量金字塔始终是直立的，表示能量含量。利用它们来解释为什么顶级捕食者数量较少。

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3. Nutrient Cycles: Carbon and Nitrogen | 营养循环：碳循环与氮循环

Nutrient cycles describe how vital elements are recycled in the environment. The carbon cycle involves photosynthesis (CO₂ uptake) and respiration (CO₂ release). Decomposers break down dead matter, returning carbon to the soil. Combustion of fossil fuels and deforestation release large amounts of CO₂, disrupting the balance.

营养循环描述了生命必需元素如何在环境中循环利用。碳循环涉及光合作用（吸收CO₂）和呼吸作用（释放CO₂）。分解者分解死亡的有机物，使碳回归土壤。化石燃料的燃烧和森林砍伐释放大量CO₂，打破了平衡。

The nitrogen cycle is essential for building proteins and DNA. Key processes: nitrogen fixation (converting N₂ gas into ammonia by bacteria in root nodules or soil), nitrification (ammonia to nitrites then nitrates by nitrifying bacteria), assimilation (plants absorb nitrates), and denitrification (nitrates back to N₂ gas by denitrifying bacteria).

氮循环对构建蛋白质和DNA至关重要。关键过程：固氮作用（根瘤菌或土壤中的细菌将氮气N₂转化为氨），硝化作用（硝化细菌将氨转化为亚硝酸盐再转化为硝酸盐），同化作用（植物吸收硝酸盐），和反硝化作用（反硝化细菌将硝酸盐还原为N₂气体）。

WJEC may ask you to label diagrams or explain the role of microorganisms. Remember that lightning also fixes small amounts of nitrogen. Decomposers drive both cycles by breaking down waste and dead organisms.

WJEC 可能要求你标记图表或解释微生物的作用。记住闪电也能固定少量氮。分解者通过分解废物和死去的生物体，驱动这两个循环。

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4. Biodiversity and Its Importance | 生物多样性及其重要性

Biodiversity is the variety of living organisms in an area, encompassing species diversity, genetic diversity, and ecosystem diversity. High biodiversity ensures ecosystem stability, resilience to change, and provides us with food, medicine, and raw materials. It also has ethical and aesthetic value.

生物多样性指一个区域内生物的种类多样性，包括物种多样性、遗传多样性和生态系统多样性。高生物多样性确保生态系统的稳定性、抵抗变化的能力，并为我们提供食物、药物和原材料。它还具有伦理和美学价值。

Human activities such as habitat destruction, pollution, over-exploitation, and introduction of invasive species are causing a rapid decline in biodiversity. Conservation methods include protecting habitats (national parks, nature reserves), captive breeding programmes, seed banks, and legislation.

人类活动，如栖息地破坏、污染、过度开发和外来物种入侵，正导致生物多样性急剧下降。保护方法包括保护栖息地（国家公园、自然保护区）、圈养繁殖计划、种子库和立法。

In the exam, you might discuss a case study like the effect of deforestation on orangutans or coral reef destruction. Always link the cause (e.g., logging) to the impact (loss of habitat → reduced biodiversity).

考试中，你可能需要讨论案例研究，例如森林砍伐对红毛猩猩的影响或珊瑚礁破坏。始终将原因（如伐木）与影响（栖息地丧失→生物多样性减少）联系起来。

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5. Pollution: Air, Water, and Land | 污染：空气、水和土地污染

Pollution is the introduction of harmful substances into the environment. Air pollution includes sulfur dioxide (SO₂) and nitrogen oxides (NOₓ), which cause acid rain, damaging trees, soils, and aquatic life. Carbon monoxide (CO) is toxic, and particulates worsen respiratory diseases.

污染是向环境中引入有害物质。空气污染包括二氧化硫（SO₂）和氮氧化物（NOₓ），它们导致酸雨，损害树木、土壤和水生生物。一氧化碳（CO）有毒，颗粒物加重呼吸道疾病。

Water pollution arises from sewage, agricultural runoff (fertilisers, pesticides), and industrial waste. Eutrophication is a major consequence: excess nitrates and phosphates cause algal blooms that block sunlight and deplete oxygen, killing fish. Land pollution includes landfill waste, toxic chemicals, and plastic accumulation.

水污染源于污水、农业径流（化肥、农药）和工业废物

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