GCSE WJEC Biology: Last-Minute Revision Notes | GCSE WJEC 生物：考前冲刺笔记

📚 GCSE WJEC Biology: Last-Minute Revision Notes | GCSE WJEC 生物：考前冲刺笔记

This set of revision notes covers the most important topics in the WJEC GCSE Biology specification. Use it as a quick-reference guide to consolidate key concepts, diagrams and practical skills before your exam.

这套复习笔记涵盖了 WJEC GCSE 生物学课程中最重要的主题。你可以把它当作考前快速参考指南，用来巩固关键概念、图示和实验技能。

1. Cell Biology | 细胞生物学

Cell structures: Animal and plant cells both contain a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. Plant cells also have a cellulose cell wall, chloroplasts and a large permanent vacuole. Bacterial cells are prokaryotes – they lack a true nucleus and have a single circular chromosome plus small rings of DNA called plasmids.

细胞结构：动物和植物细胞都含有细胞核、细胞质、细胞膜、线粒体和核糖体。植物细胞还有纤维素细胞壁、叶绿体和一个大液泡。细菌是原核生物，没有真正的细胞核，只有一条环状染色体和称为质粒的小环 DNA。

Microscopy: Total magnification = eyepiece lens magnification × objective lens magnification. Always start with the low power objective to focus, then switch to higher magnification. Prepare a thin specimen on a slide and use a coverslip to avoid air bubbles. Stains such as iodine make structures visible.

显微镜使用：总放大倍数 = 目镜放大倍数 × 物镜放大倍数。始终先用低倍镜调焦，再换用高倍镜。制片要薄，用盖玻片避免气泡，并用碘液等染剂让结构可见。

Cell division: Mitosis produces two genetically identical daughter cells and is used for growth and repair. The stages are prophase, metaphase, anaphase and telophase. Stem cells are unspecialised cells that can differentiate into many cell types and have medical potential.

细胞分裂：有丝分裂产生两个基因相同的子细胞，用于生长和修复。阶段可分为前期、中期、后期和末期。干细胞是未分化的细胞，能分化成多种细胞类型，具有医疗应用前景。

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2. Organisation | 组织层次

Digestive enzymes: Amylase breaks down starch into maltose and works best at neutral pH. Protease digests proteins into amino acids and works in the acidic stomach (pepsin) or alkaline small intestine. Lipase breaks fats into fatty acids and glycerol. Bile emulsifies fats, increasing surface area for lipase action.

消化酶：淀粉酶将淀粉分解为麦芽糖，在中性 pH 下活性最佳。蛋白酶将蛋白质分解为氨基酸，在胃中（胃蛋白酶）需酸性环境，在小肠中需碱性。脂肪酶将脂肪分解为脂肪酸和甘油。胆汁乳化脂肪，增大脂肪酶的作用面积。

Circulatory system: The heart is a double pump – the right ventricle pumps deoxygenated blood to the lungs, the left ventricle pumps oxygenated blood to the body. Arteries have thick, elastic walls to withstand high pressure; veins have valves to prevent backflow; capillaries are one cell thick to allow exchange. Blood components: red blood cells carry oxygen, white blood cells fight infection, platelets help clotting, plasma transports dissolved substances.

循环系统：心脏是双泵结构，右心室将缺氧血泵向肺部，左心室将富氧血泵向全身。动脉壁厚而有弹性，可承受高压；静脉有瓣膜防止倒流；毛细血管仅一层细胞薄，便于物质交换。血液成分：红细胞运输氧气，白细胞抵抗感染，血小板帮助凝血，血浆运输溶解的物质。

Plant transport: Xylem vessels transport water and mineral ions upwards from the roots. Phloem tubes transport sucrose and amino acids up and down the plant. Transpiration is the loss of water vapour from leaves via stomata, driven by evaporation and creating a tension that pulls water up the xylem.

植物运输：木质部将水分和矿质离子从根部向上运输。韧皮部将蔗糖和氨基酸向上、向下运输。蒸腾作用是水蒸气通过气孔从叶片散失的过程，由蒸发驱动并产生张力，将水沿木质部向上拉。

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3. Infection and Response | 感染与反应

Pathogens and spread: Bacteria, viruses, fungi and protists can cause disease. They spread through direct contact, airborne droplets, contaminated food/water or vectors. Preventing infection includes good hygiene, vaccination and isolating infected individuals.

病原体与传播：细菌、病毒、真菌和原生生物可引起疾病。它们通过直接接触、空气飞沫、受污染的食物/水或媒介传播。预防感染包括保持良好卫生、接种疫苗和隔离感染者。

Immune system: Phagocytes engulf and digest pathogens. Lymphocytes produce specific antibodies that bind to antigens, causing pathogens to clump together for phagocytosis. Antitoxins neutralise toxins released by bacteria.

免疫系统：吞噬细胞吞噬并消化病原体。淋巴细胞产生特异性抗体，与抗原结合使病原体聚集，便于吞噬。抗毒素能中和细菌释放的毒素。

Vaccination and antibiotics: Vaccines contain weakened or dead pathogens that trigger antibody production and memory cell formation, giving rapid secondary response. Antibiotics kill bacteria but not viruses. Overuse leads to antibiotic-resistant strains.

疫苗接种与抗生素：疫苗含有减毒或灭活的病原体，能触发抗体产生并生成记忆细胞，形成快速的二次应答。抗生素只杀细菌，不能杀病毒。滥用会导致抗生素耐药菌株出现。

Plant defences: Physical barriers like waxy cuticle and cell walls, plus chemical defences such as antibacterial compounds, protect plants from pathogens.

植物防御：物理屏障如蜡质角质层和细胞壁，以及化学防御如抗菌物质，保护植物免受病原体侵害。

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4. Bioenergetics | 生物能量学

Photosynthesis: The equation is 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂, taking place in chloroplasts using light energy. Limiting factors are light intensity, carbon dioxide concentration and temperature. The rate can be measured by counting oxygen bubbles from pondweed (Elodea) at different light distances.

光合作用：反应式为 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂，在叶绿体中利用光能进行。限制因素是光强度、二氧化碳浓度和温度。可通过在不同光源距离下计数水草（如伊乐藻）释放的氧气泡数量来测定速率。

Aerobic respiration: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O, releasing a large amount of energy as ATP in mitochondria. Energy is used for muscle contraction, maintaining body temperature and active transport.

有氧呼吸：C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O，在线粒体中释放大量能量（ATP）。能量用于肌肉收缩、维持体温和主动运输。

Anaerobic respiration: In animals, glucose → lactic acid, causing oxygen debt. In plants and yeast, glucose → ethanol + carbon dioxide (fermentation), used in baking and brewing.

无氧呼吸：在动物中，葡萄糖 → 乳酸，造成氧债。在植物和酵母中，葡萄糖 → 乙醇 + 二氧化碳（发酵），用于烘焙和酿酒。

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5. Homeostasis and Nervous System | 稳态与神经系统

Homeostasis: Maintaining a stable internal environment through negative feedback. Examples include blood glucose (insulin/glucagon), body temperature (sweating/shivering) and water balance (ADH).

稳态：通过负反馈维持稳定的内环境。例子包括血糖调节（胰岛素/胰高血糖素）、体温（出汗/颤抖）和水盐平衡（抗利尿激素）。

Reflex arc: Stimulus → receptor → sensory neurone → relay neurone in spinal cord → motor neurone → effector (muscle or gland). Synapses use neurotransmitters to carry impulses across the gap, ensuring one-way transmission.

反射弧：刺激→感受器→感觉神经元→脊髓中的中继神经元→运动神经元→效应器（肌肉或腺体）。突触利用神经递质跨过间隙传递冲动，保证单向传导。

The eye: To focus on near objects, the ciliary muscles contract, suspensory ligaments loosen and the lens becomes more convex. In short sight (myopia), the eyeball is too long or the lens too curved, so light focuses in front of the retina; corrected with a concave lens. Long sight (hyperopia) is corrected with a convex lens.

眼睛：看近物时，睫状肌收缩，悬韧带松弛，晶状体变凸。近视（myopia）因眼球过长或晶状体过凸，光聚焦在视网膜前，用凹透镜矫正。远视（hyperopia）用凸透镜矫正。

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6. Hormonal Coordination | 激素协调

Endocrine system: Hormones are chemical messengers secreted by glands into the blood, acting more slowly but with longer-lasting effects than nerve impulses.

内分泌系统：激素是由腺体分泌到血液中的化学信使，作用比神经冲动慢但持续时间更长。

Blood glucose regulation: When blood glucose is high, the pancreas secretes insulin, which promotes glucose uptake and conversion to glycogen in the liver. When low, glucagon stimulates glycogen breakdown into glucose. Type 1 diabetes results from insufficient insulin production.

血糖调节：血糖高时，胰岛分泌胰岛素，促进葡萄糖吸收并在肝脏转化为糖原。血糖低时，胰高血糖素促使糖原分解为葡萄糖。1 型糖尿病由胰岛素分泌不足引起。

Menstrual cycle: FSH stimulates follicle maturation and oestrogen production. Oestrogen causes LH surge, triggering ovulation. LH stimulates formation of the corpus luteum, which secretes progesterone to maintain the uterus lining. Negative and positive feedback control hormone levels.

月经周期：FSH 刺激卵泡成熟和雌激素分泌。雌激素引发 LH 高峰，导致排卵。LH 促进黄体形成，分泌孕酮以维持子宫内膜。负反馈和正反馈共同调控激素水平。

Plant hormones: Auxin accumulates on the shaded side of a shoot, causing cells to elongate more than on the light side, making the shoot bend towards light (phototropism). Gravitropism works similarly with auxin distribution.

植物激素：生长素在茎的背光侧积聚，刺激细胞伸长程度高于向光侧，使茎向光弯曲（向光性）。向地性也通过生长素分布实现。

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7. Inheritance, Variation and Evolution | 遗传、变异与进化

DNA and inheritance: DNA is a double helix polymer made of nucleotides. A gene is a section of DNA that codes for a protein. Alleles are different versions of a gene. Dominant alleles mask recessive ones. Homozygous (two same alleles), heterozygous (two different). A monohybrid cross between heterozygous parents gives a 3:1 phenotype ratio.

DNA 与遗传：DNA 是由核苷酸组成的双螺旋聚合物。基因是编码蛋白质的 DNA 片段。等位基因是基因的不同形式。显性等位基因掩盖隐性。纯合子（两个相同等位基因），杂合子（两个不同）。杂合亲本的单基因杂交后代表型比为 3:1。

Meiosis and variation: Meiosis produces gametes with half the chromosome number and generates genetic variation through independent assortment and crossing over. Sexual reproduction combines genetic material from two parents.

减数分裂与变异：减数分裂产生染色体数减半的配子，并通过独立分配和交叉互换产生遗传变异。有性生殖结合了两个亲本的遗传物质。

Natural selection and evolution: Organisms with advantageous adaptations survive and reproduce, passing on beneficial alleles. Over generations, the frequency of these alleles increases, leading to evolution. Speciation can occur when populations are geographically isolated and accumulate differences so they can no longer interbreed.

自然选择与进化：具有有利适应性的生物生存并繁殖，将有利等位基因传递下去。经过多代，这些等位基因频率增加，导致进化。当种群被地理隔离并积累差异至无法交配时，就会形成新物种。

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8. Ecology | 生态学

Ecosystems and energy flow: Food chains show feeding relationships: producer → primary consumer → secondary consumer → tertiary consumer. Only about 10% of energy is transferred between trophic levels; the rest is lost as heat from respiration, movement and waste. This explains pyramid-shaped biomass and numbers.

生态系统与能量流动：食物链显示吃与被吃关系：生产者→初级消费者→次级消费者→三级消费者。能量在营养级之间仅约 10% 传递，其余以呼吸热、运动和排泄物等形式散失，这解释了生物量和数量呈金字塔形。

Nutrient cycles: In the carbon cycle, photosynthesis removes CO₂ from the atmosphere, and respiration, combustion and decomposition return it. The water cycle involves evaporation, transpiration, condensation and precipitation.

物质循环：碳循环中，光合作用从大气中移走 CO₂，呼吸作用、

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