📚 Year 11 Cambridge Biology: Core Concepts Revision | 11年级剑桥生物：核心知识点梳理
This article brings together the essential knowledge areas from the Cambridge IGCSE Biology syllabus for Year 11. A strong grasp of these core concepts will help you tackle exam questions with confidence and build a solid foundation for further study.
本文汇集了11年级剑桥IGCSE生物学教学大纲中的核心知识点。牢固掌握这些基本概念，将帮助你自信应对考试题目，并为后续学习打下坚实基础。
1. Cell Structure and Organisation | 细胞结构与组织
All living organisms are composed of cells, which are the basic structural and functional units of life. Some organisms are unicellular, while others are multicellular with specialised cells organised into tissues, organs and organ systems.
所有生物体都由细胞组成，细胞是生命的基本结构和功能单位。有些生物是单细胞的，而另一些是多细胞的，其特化的细胞构成组织、器官和器官系统。
Animal cells contain a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. Plant cells have the same plus a cell wall, chloroplasts and a permanent vacuole.
动物细胞含有细胞核、细胞质、细胞膜、线粒体和核糖体。植物细胞除此之外还有细胞壁、叶绿体和一个中央大液泡。
Bacterial cells are prokaryotic – they lack a nucleus and membrane-bound organelles. Their DNA is a single circular chromosome, and they may have plasmids.
细菌细胞是原核细胞——它们缺乏细胞核和膜包被的细胞器。它们的DNA是一条环状染色体，可能还含有质粒。
2. Movement In and Out of Cells | 物质进出细胞
Substances move across cell membranes by diffusion, osmosis and active transport. Each process depends on the concentration gradient and energy requirements.
物质通过扩散、渗透和主动运输穿过细胞膜。每种过程取决于浓度梯度和能量需求。
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 and does not require energy.
扩散是粒子从高浓度区域向低浓度区域沿浓度梯度净移动的过程，属于被动过程，不需要能量。
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.
渗透是水分子通过半透膜从水势较高的区域向水势较低的区域扩散的过程。
Active transport requires energy (ATP) to move substances against their concentration gradient, using carrier proteins in the cell membrane.
主动运输需要能量（ATP）使物质逆浓度梯度移动，通过细胞膜上的载体蛋白实现。
3. Biological Molecules and Enzymes | 生物分子与酶
Living organisms rely on large organic molecules: carbohydrates, lipids, proteins and nucleic acids. Enzymes are proteins that catalyse biochemical reactions.
生物体依赖大分子有机物：碳水化合物、脂类、蛋白质和核酸。酶是催化生化反应的蛋白质。
Carbohydrates are made of simple sugars (e.g. glucose) and include starch and cellulose in plants, and glycogen in animals – all built from monosaccharides.
碳水化合物由单糖（如葡萄糖）组成，包括植物中的淀粉和纤维素，以及动物中的糖原——均由单糖构成。
Lipids are composed of fatty acids and glycerol, used for energy storage, insulation and forming cell membranes.
脂类由脂肪酸和甘油组成，用于能量储存、保温和构成细胞膜。
Proteins are polymers of amino acids. Enzymes have an active site complementary to a specific substrate. The 'lock and key' model explains their specificity.
蛋白质是氨基酸的聚合物。酶具有与特定底物互补的活性位点。‘锁钥模型’解释了其特异性。
Enzyme activity is affected by temperature and pH. Extremes of temperature or pH can denature the enzyme, altering the shape of its active site.
酶活性受温度和pH值影响。极端的温度或pH可使酶变性，改变其活性位点形状。
4. Plant Nutrition and Photosynthesis | 植物营养与光合作用
Plants are autotrophs, meaning they make their own food using photosynthesis. Photosynthesis takes place in chloroplasts and uses light energy to convert carbon dioxide and water into glucose and oxygen.
植物是自养生物，通过光合作用制造食物。光合作用发生在叶绿体中，利用光能将二氧化碳和水转化为葡萄糖和氧气。
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
The rate of photosynthesis is influenced by light intensity, carbon dioxide concentration and temperature, with one often acting as the limiting factor.
光合作用速率受光照强度、二氧化碳浓度和温度影响，其中某一个因素常会成为限制因子。
The leaf is adapted for photosynthesis: broad, thin, with many chloroplasts in the palisade layer, and stomata for gas exchange.
叶片适应光合作用：扁平而薄，栅栏组织中有大量叶绿体，并具有用于气体交换的气孔。
Plants also require mineral ions such as nitrate ions (for making amino acids) and magnesium ions (for making chlorophyll).
植物还需要无机盐离子，如硝酸根离子（用于合成氨基酸）和镁离子（用于合成叶绿素）。
5. Human Nutrition and Digestion | 人类营养与消化
A balanced diet includes carbohydrates, proteins, lipids, vitamins, minerals, water and dietary fibre. The digestive system breaks down large insoluble molecules into small soluble molecules that can be absorbed.
均衡膳食包括碳水化合物、蛋白质、脂类、维生素、无机盐、水和膳食纤维。消化系统将不溶的大分子分解为可溶的小分子以便吸收。
Mechanical digestion occurs through chewing and muscle action, while chemical digestion uses enzymes such as amylase (starch to maltose) and proteases (proteins to amino acids).
物理消化通过咀嚼和肌肉运动实现，化学消化则依靠酶，如淀粉酶（淀粉→麦芽糖）和蛋白酶（蛋白质→氨基酸）。
The small intestine is the main site of nutrient absorption. Its inner surface has villi and microvilli to increase surface area.
小肠是营养吸收的主要场所。其内表面有绒毛和微绒毛以增加表面积。
Peristalsis is the wave-like muscle contraction that moves food along the alimentary canal.
蠕动是推动食物沿消化道前进的波浪式肌肉收缩。
6. Respiration | 呼吸作用
Respiration is the process by which cells release energy from food molecules, primarily glucose. It is not the same as breathing; it occurs in all living cells.
呼吸作用是细胞从食物分子（主要是葡萄糖）中释放能量的过程。它不同于呼吸动作，发生在所有活细胞中。
Aerobic respiration requires oxygen and produces a large amount of energy. The overall equation is: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 38 ATP (approximate).
有氧呼吸需要氧气，产生大量能量。总方程式为：C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 约38 ATP。
Anaerobic respiration in humans produces lactic acid and releases a small amount of energy. In yeast, it produces ethanol and carbon dioxide – known as fermentation.
人体的无氧呼吸产生乳酸并释放少量能量。酵母的无氧呼吸产生乙醇和二氧化碳，即发酵。
Anaerobic respiration is useful during short bursts of intense exercise, but the build-up of lactic acid causes muscle fatigue.
无氧呼吸在短时间剧烈运动中发挥作用，但乳酸的积累会导致肌肉疲劳。
7. Gas Exchange and Breathing | 气体交换与呼吸
The respiratory system enables the uptake of oxygen and removal of carbon dioxide. Gas exchange takes place across the thin, moist walls of the alveoli in the lungs.
呼吸系统实现氧气的摄取和二氧化碳的排出。气体交换在肺部肺泡薄而湿润的壁上进行。
Inhaled air moves through the trachea, bronchi, bronchioles and finally into alveoli. The alveoli have a large surface area, a rich blood supply and short diffusion distance.
吸入的空气经气管、支气管、细支气管最终到达肺泡。肺泡具有较大的表面积、丰富的血液供应和短的扩散距离。
Smoking damages the respiratory system: it destroys cilia, increases mucus production, and can cause emphysema, chronic bronchitis and lung cancer.
吸烟损害呼吸系统：破坏纤毛，增加粘液分泌，并可能导致肺气肿、慢性支气管炎和肺癌。
The intercostal muscles and diaphragm work together to change the volume of the thorax, creating pressure changes that drive ventilation.
肋间肌与膈肌协同改变胸腔容积，产生压力变化从而驱动肺通气。
8. Transport in Plants and Animals | 动植物运输
Multicellular organisms rely on transport systems to supply cells with oxygen and nutrients and to remove waste products.
多细胞生物依赖运输系统为细胞提供氧气和营养物质，并带走废物。
In plants, xylem transports water and mineral ions from roots to leaves. Phloem transports sucrose and amino acids up and down the plant (translocation).
植物中，木质部将水和无机盐从根部运往叶片。韧皮部将蔗糖和氨基酸在植物体内上下运输（传输作用）。
Transpiration is the loss of water vapour from leaves, creating a pull that draws water up the xylem. Factors such as temperature, humidity and light intensity affect transpiration rate.
蒸腾作用是水蒸气从叶片散失的过程，产生拉力将水沿木质部向上牵引。温度、湿度和光照强度等因素影响蒸腾速率。
The human circulatory system consists of the heart, blood vessels and blood. The heart is a double pump; the right side pumps blood to the lungs, the left side to the body.
人体循环系统包括心脏、血管和血液。心脏是一个双泵；右侧将血液泵至肺部，左侧泵至全身。
Red blood cells transport oxygen using haemoglobin, white blood cells defend against pathogens, and platelets help in blood clotting.
红细胞利用血红蛋白运输氧气，白细胞抵御病原体，血小板协助血液凝固。
9. Excretion and Homeostasis | 排泄与稳态
Excretion is the removal of metabolic waste products and substances in excess from the body. The kidneys play a central role in excretion and in maintaining homeostasis.
排泄是清除体内代谢废物和多余物质的过程。肾脏在排泄和维持稳态中起核心作用。
Each kidney contains thousands of nephrons. Blood is filtered in the glomerulus, and useful substances are reabsorbed along the tubule.
每个肾脏含有数千个肾单位。血液在肾小球中过滤，有用物质在肾小管中被重吸收。
Urine contains mainly water, urea and excess ions. ADH (antidiuretic hormone) regulates the reabsorption of water, helping to maintain water balance.
尿液主要含有水、尿素和多余离子。抗利尿激素（ADH）调节水的重吸收，帮助维持水分平衡。
Homeostasis also involves maintaining constant body temperature, blood glucose levels and pH. The skin, liver and pancreas all contribute to these regulatory processes.
稳态还包括维持恒定的体温、血糖水平和pH值。皮肤、肝脏和胰腺都参与这些调节过程。
10. Coordination and Response | 协调与反应
Organisms respond to changes in their environment through nervous and hormonal systems, enabling them to react to stimuli and maintain internal balance.
生物通过神经系统和激素系统对环境变化作出反应，从而对刺激作出应答并维持内部平衡。
A reflex arc involves a receptor, sensory neurone, relay neurone (in the spinal cord), motor neurone and effector. Reflexes are rapid and involuntary.
反射弧包括感受器、感觉神经元、中间神经元（位于脊髓）、运动神经元和效应器。反射是快速且非自主的。
The human eye adjusts to light intensity: in bright light, the iris reflex contracts the pupil. Focusing is achieved by changing the shape of the lens (accommodation).
人眼对光强作出调整：强光下虹膜反射使瞳孔缩小。通过改变晶状体形状实现对焦（调节作用）。
Hormones are chemical messengers transported in the blood. Adrenaline prepares the body for 'fight or flight'. Insulin lowers blood glucose, while glucagon raises it.
激素是通过血液运输的化学信使。肾上腺素为‘战斗或逃跑’反应做准备。胰岛素降低血糖，而胰高血糖素升高血糖。
11. Reproduction and Inheritance | 生殖与遗传
Reproduction can be asexual, producing genetically identical offspring, or sexual, involving the fusion of gametes and leading to variation.
生殖可以是无性的，产生遗传上相同的后代；或是有性的，通过配子融合并导致变异。
In humans, the male gamete is the sperm and the female gamete is the egg. Fertilisation occurs in the oviduct, and the developing embryo implants in the uterus.
人类中，雄性配子是精子，雌性配子是卵细胞。受精发生在输卵管，发育中的胚胎着床于子宫。
DNA is a double helix carrying genetic information in genes. A gene is a section of DNA that codes for a particular protein.
DNA是双螺旋结构，以基因为单位携带遗传信息。基因是编码特定蛋白质的DNA片段。
Alleles are different forms of a gene. Dominant alleles mask recessive ones. Genetic crosses can be shown using Punnett squares.
等位基因是基因的不同形式。显性等位基因掩盖隐性等位基因。遗传杂交可通过庞尼特方格表示。
Variation may be continuous or discontinuous and arises from genetic differences and environmental influences.
变异可以是连续的或不连续的，起因于遗传差异和环境影响。
12. Organisms and Their Environment | 生物与环境
Ecology studies the interactions between organisms and their surroundings. Food chains and food webs show the flow of energy through an ecosystem.
生态学研究生物与其环境之间的相互作用。食物链和食物网展示了能量在生态系统中的流动。
Energy enters most ecosystems through producers (plants) that carry out photosynthesis. Energy decreases at each trophic level due to respiration, movement and waste.
能量通过进行光合作用的生产者（植物）进入大多数生态系统。由于呼吸、运动和废物等消耗，能量在每一营养级递减。
The carbon cycle involves photosynthesis, respiration, decomposition and combustion. Decomposers such as bacteria and fungi recycle organic matter.
碳循环涉及光合作用、呼吸作用、分解和燃烧。细菌和真菌等分解者对有机物进行再循环。
Population size can be influenced by food availability, predation, disease and competition. Human activities can have significant impacts, including pollution and habitat destruction.
种群大小受食物供应、捕食、疾病和竞争的影响。人类活动（包括污染和栖息地破坏）可产生重大影响。
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