GCSE WJEC Science: Animal Revision Guide | GCSE WJEC科学：动物考点精讲

📚 GCSE WJEC Science: Animal Revision Guide | GCSE WJEC科学：动物考点精讲

This revision guide covers the key topics in animal biology for GCSE WJEC Science. It explores cell structure, transport, organ systems, and how animals maintain a stable internal environment. Each section is designed to help you master the essential concepts needed for your exams, with clear bilingual explanations.

本复习指南涵盖GCSE WJEC科学中动物生物学的重要考点，包括细胞结构、物质运输、器官系统以及动物如何维持内环境稳定。每一部分都通过清晰的双语解释，帮助你掌握考试必备的核心概念。

1. Animal Cell Structure | 动物细胞结构

Animal cells are eukaryotic and contain a nucleus, cytoplasm, cell membrane, mitochondria, and ribosomes.
动物细胞是真核细胞，含有细胞核、细胞质、细胞膜、线粒体和核糖体。
The nucleus controls cell activities and contains genetic material (DNA).
细胞核控制细胞活动，并含有遗传物质（DNA）。
Cytoplasm is a jelly-like substance where most chemical reactions occur.
细胞质是一种胶状物质，大多数化学反应在其中进行。
The cell membrane is selectively permeable and controls the movement of substances in and out of the cell.
细胞膜具有选择透过性，控制物质进出细胞。
Mitochondria are the sites of aerobic respiration, releasing energy in the form of ATP.
线粒体是有氧呼吸的场所，以ATP的形式释放能量。
Ribosomes synthesise proteins by linking amino acids together.
核糖体通过连接氨基酸来合成蛋白质。
Unlike plant cells, animal cells do not have a cell wall, chloroplasts, or a large permanent vacuole.
与植物细胞不同，动物细胞没有细胞壁、叶绿体和大液泡。

2. Transport Across Cell Membranes | 跨膜运输

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 does not require energy.
扩散是粒子从高浓度区域向低浓度区域的净移动，顺浓度梯度进行，是一个不消耗能量的被动过程。
Examples of diffusion include oxygen moving from the alveoli into the blood and carbon dioxide moving from the blood into the alveoli.
扩散的例子包括氧气从肺泡进入血液，以及二氧化碳从血液进入肺泡。
Osmosis is the diffusion of water molecules through a partially permeable membrane from a region of higher water potential to a region of lower water potential.
渗透是水分子通过部分透膜从水势较高的区域向水势较低的区域扩散。
Animal cells can burst (lysis) if placed in a hypotonic solution because water enters the cell by osmosis.
如果动物细胞置于低渗溶液中，水会通过渗透进入细胞，可能导致细胞破裂（溶解）。
Active transport is the movement of substances against a concentration gradient, from low to high concentration. It requires energy from respiration and carrier proteins in the membrane.
主动运输是物质逆浓度梯度（从低浓度到高浓度）的移动，需要呼吸作用提供能量以及膜上的载体蛋白。
An example is the absorption of glucose by the villi in the small intestine, where glucose is taken up even when its concentration is lower in the gut lumen.
例如小肠绒毛吸收葡萄糖，即使肠腔内的葡萄糖浓度较低，也能被吸收。

3. Tissues, Organs and Organ Systems | 组织、器官与器官系统

Cells of the same type group together to form a tissue. Examples of animal tissues include epithelial tissue (lining surfaces), muscle tissue (contraction), nervous tissue (transmitting impulses), and connective tissue (support).
相同类型的细胞聚集在一起形成组织。动物组织包括上皮组织（覆盖表面）、肌肉组织（收缩）、神经组织（传递冲动）和结缔组织（提供支持）。
An organ is made up of different tissues working together to perform a specific function. The stomach is an organ that contains muscle tissue, glandular tissue, and epithelial tissue.
器官由不同的组织协同工作以完成特定功能。胃是一个器官，含有肌肉组织、腺体组织和上皮组织。
Organ systems are groups of organs that work together to carry out a major body function. Examples include the digestive system, circulatory system, and nervous system.
器官系统是多个器官共同完成一项主要生理功能，例如消化系统、循环系统和神经系统。
Specialised cells are adapted to their function. Red blood cells have a biconcave shape and no nucleus to increase space for haemoglobin; nerve cells have long axons to transmit signals over distances.
特化细胞适应其功能。红细胞呈双凹圆盘状且无细胞核，为血红蛋白腾出空间；神经细胞有长轴突，可长距离传递信号。

4. Digestive System and Enzymes | 消化系统与酶

The digestive system breaks down large insoluble food molecules into small soluble ones that can be absorbed into the bloodstream.
消化系统将大而不溶的食物分子分解为小可溶的分子，以便吸收进入血液。
Mechanical digestion occurs in the mouth (chewing) and stomach (churning), increasing the surface area for enzyme action.
物理消化发生在口腔（咀嚼）和胃（搅拌），增加酶作用的表面积。
Chemical digestion uses enzymes. Amylase (in saliva and pancreatic juice) breaks starch into maltose. Proteases (in stomach and pancreatic juice) break proteins into amino acids. Lipases (from pancreas) break lipids into fatty acids and glycerol.
化学消化依靠酶。淀粉酶（存在于唾液和胰液中）将淀粉分解为麦芽糖。蛋白酶（存在于胃液和胰液中）将蛋白质分解为氨基酸。脂肪酶（来自胰腺）将脂肪分解为脂肪酸和甘油。
Enzymes are biological catalysts made of protein. They have an active site with a specific shape that fits the substrate like a lock and key. This lowers the activation energy for the reaction.
酶是由蛋白质组成的生物催化剂。它们有一个形状特异的活性位点，犹如锁与钥匙一样与底物匹配，从而降低反应活化能。
Enzymes are affected by temperature and pH. At low temperatures, enzyme activity is slow. As temperature rises, activity increases until an optimum is reached. Above the optimum, the enzyme denatures – the active site changes shape permanently.
酶受温度和pH影响。低温时酶活性较低；温度升高活性增强直至最适温度；超过最适温度酶会变性，活性位点永久改变。
The stomach produces hydrochloric acid, which kills bacteria and provides the acidic optimum (pH 2) for pepsin. Bile from the liver neutralises stomach acid and emulsifies fats, increasing the surface area for lipase.
胃产生盐酸，可杀死细菌并为胃蛋白酶提供最适酸性环境（pH 2）。来自肝脏的胆汁能中和胃酸并乳化脂肪，增大脂肪酶作用的表面积。

5. Circulatory System | 循环系统

The human circulatory system consists of the heart, blood vessels, and blood. It is a double circulatory system: one circuit carries blood from the heart to the lungs (pulmonary circulation), and the other carries blood from the heart to the rest of the body (systemic circulation).
人体循环系统由心脏、血管和血液组成，属于双循环系统：一条回路将血液从心脏输送到肺部（肺循环），另一条将血液从心脏输送到全身（体循环）。
The heart has four chambers: right atrium, right ventricle, left atrium, and left ventricle. The left ventricle has a thicker muscular wall because it pumps blood around the whole body at high pressure.
心脏有四个腔室：右心房、右心室、左心房和左心室。左心室壁较厚，因为它需要以高压将血液泵送到全身。
Blood vessels include arteries, veins, and capillaries. Arteries carry blood away from the heart; they have thick, elastic walls to withstand high pressure. Veins carry blood towards the heart; they have thinner walls and valves to prevent backflow. Capillaries are one-cell thick to allow efficient exchange of substances.
血管包括动脉、静脉和毛细血管。动脉将血液运离心脏，管壁厚而富有弹性以承受高压。静脉将血液送回心脏，管壁较薄且有瓣膜防止倒流。毛细血管壁仅有一层细胞厚，便于物质交换。
Blood is composed of red blood cells (transport oxygen bound to haemoglobin), white blood cells (defence against pathogens), platelets (clotting), and plasma (transports carbon dioxide, glucose, amino acids, hormones, and heat).
血液由红细胞（运输与血红蛋白结合的氧气）、白细胞（防御病原体）、血小板（凝血）和血浆（运输二氧化碳、葡萄糖、氨基酸、激素和热量）组成。

6. Respiratory System | 呼吸系统

Air enters the body through the nose or mouth, passes down the trachea, bronchi, bronchioles, and finally reaches the alveoli in the lungs.
空气通过鼻或口进入人体，沿气管、支气管、细支气管下行，最终到达肺部的肺泡。
Gas exchange occurs in the alveoli. Alveoli have thin walls (one cell thick), a large surface area, a moist lining, and a rich blood supply from surrounding capillaries – all adaptations for efficient diffusion.
气体交换在肺泡进行。肺泡壁薄（一层细胞厚度）、表面积大、内壁湿润并有丰富的毛细血管围绕，这些特征均有利于高效扩散。
Oxygen diffuses from the alveoli into the blood, where it binds to haemoglobin. Carbon dioxide diffuses from the blood into the alveoli to be exhaled.
氧气从肺泡扩散入血并与血红蛋白结合；二氧化碳从血液扩散至肺泡并呼出。
Inhalation is an active process. The intercostal muscles and diaphragm contract. The ribcage moves up and out, the diaphragm flattens, increasing the volume of the thorax and lowering the pressure, causing air to rush in.
吸气是一个主动过程：肋间肌和膈肌收缩，肋骨上移外扩，膈肌下降，胸腔容积增大，内部气压降低，空气涌入肺内。
Exhalation is largely passive. The intercostal muscles and diaphragm relax, the ribcage moves down and in, the diaphragm returns to its dome shape, reducing thorax volume and forcing air out.
呼气基本上是被动过程：肋间肌和膈肌放松，肋骨下移内收，膈肌恢复穹顶形，胸腔容积减小，将空气挤出。
Aerobic respiration uses oxygen to release energy: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O (+ ATP). Anaerobic respiration in animals produces lactic acid and much less ATP: glucose → lactic acid.
有氧呼吸利用氧气释放能量：C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O (+ ATP)。动物无氧呼吸产生乳酸和少量ATP：葡萄糖 → 乳酸。

7. Excretory System | 排泄系统

The kidneys filter blood to remove toxic waste products such as urea (produced from the breakdown of amino acids) and to regulate water and ion balance.
肾脏过滤血液以移除有毒废物如尿素（来自氨基酸分解），并调节水分和离子平衡。
Each kidney contains millions of nephrons, the functional units. Blood enters the nephron through the afferent arteriole and is filtered in the glomerulus under high pressure.
每个肾脏含有数百万个肾单位，即功能单位。血液经入球小动脉进入肾单位，在肾小球中受高压过滤。
During filtration, water, glucose, urea, and ions are forced out of the blood into the Bowman’s capsule. Large molecules such as proteins and blood cells remain in the blood.
过滤时，水、葡萄糖、尿素和离子被压出血液，进入鲍曼囊中。大分子如蛋白质和血细胞则留在血液中。
Selective reabsorption occurs in the convoluted tubules. All glucose and some water and ions are reabsorbed back into the blood. Urea and excess water form urine.
选择性重吸收发生在肾小管中。全部葡萄糖以及部分水和离子被重新吸收回血液。尿素和多余的水分形成尿液。
The hormone ADH (antidiuretic hormone) controls the amount of water reabsorbed. When blood water potential is low, more ADH is released, making the collecting duct more permeable to water, so more water is reabsorbed and urine becomes more concentrated.
抗利尿激素（ADH）控制水的重吸收量。当血液水势较低时，释放更多的ADH，使集合管对水的通透性增加，从而重吸收更多的水，尿液变得浓缩。

8. Nervous System | 神经系统

The nervous system enables rapid communication between different parts of the body. It consists of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves).
神经系统使身体各部分之间能够快速通信，由中枢神经系统（脑和脊髓）和周围神经系统（神经）组成。
Neurones (nerve cells) are specialised to transmit electrical impulses. A typical motor neurone has a cell body, dendrites, a long axon covered by a myelin sheath, and synaptic endings.
神经元（神经细胞）特化以传递电冲动。典型的运动神经元具有细胞体、树突、长长且被髓鞘包裹的轴突以及突触末梢。
Myelin sheaths insulate the axon and speed up the transmission of the impulse.
髓鞘能绝缘轴突并加快冲动传递。
Signals cross the gap (synapse) between two neurones by the release of chemical neurotransmitters, which diffuse across the synapse and bind to receptors on the next neurone.
信号通过释放化学递质跨越两个神经元之间的间隙（突触），递质在突触间扩散并与下一个神经元的受体结合。
A reflex arc is an automatic, rapid response to a stimulus that often bypasses the brain. The pathway: stimulus → receptor → sensory neurone → relay neurone (in CNS) → motor neurone → effector (muscle or gland).
反射弧是对刺激的自动快速反应，通常不经过脑。路径为：刺激 → 感受器 → 感觉神经元 → 中间神经元（中枢神经系统内） → 运动神经元 → 效应器（肌肉或腺体）。
Reflexes are protective, for example pulling the hand away from a hot object. The decision is made by the spinal cord to minimise response time.
反射具有保护作用，如手碰到热物体立即缩回。由脊髓做出决定，以缩短反应时间。

9. Hormonal System | 激素系统

The endocrine system uses hormones – chemical messengers released into the blood by endocrine glands – to coordinate slower but longer-lasting responses than the nervous system.
内分泌系统利用激素——由内分泌腺分泌并释放入血的化学信使——来协调反应，与神经系统相比反应较慢但作用更持久。
Insulin is produced by the pancreas when blood glucose levels are high. It prompts liver and muscle cells to take up glucose and convert it into glycogen for storage, lowering blood glucose.
血糖水平升高时，胰腺分泌胰岛素，促进肝细胞和肌细胞摄取葡萄糖并将其转化为糖原储存，从而降低血糖。
Glucagon is produced when blood glucose is low. It causes the liver to break down glycogen back into glucose and release it into the blood.
血糖降低时，胰腺分泌胰高血糖素，促使肝脏将糖原分解为葡萄糖并释放入血。
Type 1 diabetes is a condition where the pancreas fails to produce enough insulin. It is often managed by injecting insulin and monitoring diet.
1型糖尿病是由于胰腺无法产生足够胰岛素所致，通常通过注射胰岛素和控制饮食进行管理。
Adrenaline is released by the adrenal glands in times of fear or stress (the ‘fight or flight’ response). It increases heart rate, breathing rate, and blood flow to muscles, and triggers the liver to release more glucose for energy.
在恐惧或压力时（“战斗或逃跑”反应），肾上腺释放肾上腺素，使心率、呼吸和肌肉血流增加，并促使肝脏释放更多葡萄糖提供能量。
Negative feedback is a key control mechanism: a change in a condition is detected, and a response is triggered to reverse that change, bringing the level back to normal. Both blood glucose regulation and ADH control are examples.
负反馈是一种关键的控制机制：检测到条件变化后，触发逆转该变化的响应，使水平恢复至正常。血糖调节和ADH控制均是典型例子。

10. Reproductive System | 生殖系统

The male reproductive system produces sperm and the hormone testosterone. Sperm are produced in the testes and travel through the sperm duct. Testosterone is responsible for secondary sexual characteristics such as facial hair and deepening of the voice.
男性生殖系统产生精子和雄激素睾酮。精子在睾丸生成并通过输精管运输。睾酮控制男性第二性征，如胡须和变声。
The female reproductive system produces egg cells (ova) and the hormones oestrogen and progesterone. Ovaries release an egg approximately every 28 days (ovulation). Oestrogen and progesterone regulate the menstrual cycle and secondary sexual characteristics.
女性生殖系统产生卵子和雌激素、孕激素。卵巢大约每28天释放一个卵子（排卵）。雌激素和孕激素调节月经周期和女性第二性征。
Fertilisation occurs when a sperm nucleus fuses with an egg nucleus in the oviduct (fallopian tube) to form a zygote, which then divides and implants into the uterus lining.
受精发生在输卵管内，精核与卵核融合形成受精卵，随后分裂并植入子宫内膜。
The placenta acts as the interface between mother and foetus, allowing the exchange of nutrients, oxygen, and waste products without mixing of blood. The amniotic fluid protects the developing foetus from physical shocks.
胎盘是母体与胎儿之间的交换界面，允许营养物质、氧气和废物的交换，且双方血液不混合。羊水保护发育中的胎儿免受机械冲击。

11. Homeostasis | 体内平衡

Homeostasis is the maintenance of a constant internal environment within the body. Key regulated factors include body temperature, blood glucose, water potential, and carbon dioxide concentration.
体内平衡是指维持身体内环境的稳定。关键调控因素包括体温、血糖、水势和二氧化碳浓度。
Thermoregulation is controlled by the thermoregulatory centre in the brain (hypothalamus). If the body temperature is too high, Vasodilation of skin arterioles increases blood flow near the skin surface to lose heat; sweat glands secrete sweat for evaporation cooling.
体温调节由脑中的体温调节中枢（下丘脑）控制。体温过高时，皮肤小动脉舒张，增加皮肤表面血流量以散热；汗腺分泌汗液，通过蒸发降温。
If body temperature falls below normal, Vasoconstriction reduces skin blood flow to conserve heat; skeletal muscles undergo shivering to generate heat; hairs stand up (piloerection) to trap an insulating layer of air.
体温过低时，皮肤血管收缩以减少热量散失；骨骼肌颤栗产热；毛发竖立（竖毛作用）可留住保温空气层。
Blood glucose regulation and osmoregulation (ADH) are also examples of negative feedback, maintaining levels around a set point.
血糖调节和渗透压调节（ADH）同样属于负反馈，将各项水平维持在设定点附近。

12. Disease and Defence | 疾病与防御

Pathogens are microorganisms that cause infectious diseases. They include bacteria, viruses, fungi, and protists. Each pathogen has specific methods of transmission, such as through the air (droplets), direct contact, contaminated food or water, and vectors.
病原体是引起传染病的微生物，包括细菌、病毒、真菌和原生生物。每种病原体有特定的传播方式，如空气（飞沫）、直接接触、污染的食物或水，以及媒介生物等。
The body’s primary barriers against pathogens include the skin (physical barrier), mucus in airways (traps pathogens), stomach acid (kills swallowed pathogens), and tears (contain lysozyme).
机体防御病原体的第一道屏障包括皮肤（物理屏障）、呼吸道黏液（捕捉病原体）、胃酸（杀死吞咽的病原体）和泪液（含有溶菌酶）。
White blood cells provide internal defence. Phagocytes engulf and digest pathogens in a process called phagocytosis. Lymphocytes produce specific antibodies that bind to antigens on the pathogen, marking them for destruction.
白细胞提供内部防御。吞噬细胞通过吞噬作用包裹并消化病原体。淋巴细胞产生特异性抗体，结合病原体表面抗原并将其标记为待摧毁。
Once an infection is cleared, some lymphocytes remain as memory cells. If the same pathogen invades again, the response is much faster and stronger, often preventing illness. This is the basis of immunity.
感染消除后，部分淋巴细胞作为记忆细胞留存。若相同病原体再次入侵，反应将更快更强，通常能防止发病，这就是免疫力的基础。
Vaccination introduces a dead or weakened form of a pathogen into the body. This triggers an immune response and production of memory cells without causing the disease, providing future protection against the real pathogen.
疫苗接种将灭活或减毒的病原体引入体内，激发免疫反应和记忆细胞的生成，而不引起疾病本身，从而为将来抵御真正的病原体提供保护。

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GCSE WJEC Science: Animal Revision Guide | GCSE WJEC科学：动物考点精讲