📚 Year 10 CCEA Biology: Core Knowledge Revision | Year 10 CCEA 生物：核心知识点梳理
This article summarises the key topics in the Year 10 CCEA Biology course, covering cell biology, human physiology, plant biology, ecology and genetics. Understanding these fundamentals will build a strong foundation for GCSE success.
本文梳理了Year 10 CCEA生物课程的核心主题，涵盖细胞生物学、人体生理学、植物生物学、生态学和遗传学。掌握这些基础知识将为GCSE的成功打下坚实基础。
1. Cell Structure and Function | 细胞结构与功能
All living organisms are composed of cells, which are the basic structural and functional units of life. In multicellular organisms, cells differentiate to perform specialised roles, forming tissues and organs.
所有生物体都由细胞构成，细胞是生命的基本结构与功能单位。在多细胞生物中，细胞经分化行使特定功能，进而形成组织和器官。
Animal cells typically contain a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. Plant cells possess the same organelles but also have a rigid cellulose cell wall, a large permanent vacuole for storage and support, and chloroplasts where photosynthesis occurs. Bacterial cells are prokaryotic, lacking a distinct nucleus; their DNA floats freely in the cytoplasm, and they have a cell wall but no mitochondria or chloroplasts.
动物细胞通常包含细胞核、细胞质、细胞膜、线粒体和核糖体。植物细胞拥有相同的细胞器，此外还具有坚硬的纤维素细胞壁、用于储存和支持的大液泡，以及进行光合作用的叶绿体。细菌细胞是原核细胞，没有明显的细胞核，其DNA在细胞质中游离，有细胞壁但没有线粒体或叶绿体。
The nucleus controls the cell’s activities and stores genetic information. Mitochondria are the site of aerobic respiration, releasing energy for cellular processes. Ribosomes synthesise proteins. The cell membrane selectively controls the movement of substances in and out of the cell.
细胞核控制细胞活动并储存遗传信息。线粒体是有氧呼吸的场所，为细胞活动释放能量。核糖体合成蛋白质。细胞膜选择性地控制物质进出细胞。
2. Transport across Membranes | 物质通过膜运输
Substances move across cell membranes by diffusion, osmosis and active transport. Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration, down a concentration gradient. It is a passive process and does not require energy. Gaseous exchange in the alveoli relies on diffusion.
物质通过扩散、渗透和主动运输进出细胞膜。扩散是粒子沿着浓度梯度从较高浓度区域向较低浓度区域的净移动，是一种被动过程，不消耗能量。肺泡中的气体交换就依赖于扩散。
Osmosis is the diffusion of water molecules through a partially permeable membrane from a dilute solution to a more concentrated solution. Plant roots absorb water by osmosis, and turgor pressure supports non-woody stems.
渗透是水分子通过部分透性膜从稀溶液向较浓溶液进行的扩散。植物根系通过渗透作用吸水，膨压为草本植物的茎提供支撑。
Active transport moves substances against the concentration gradient, from low to high concentration, using energy from respiration. Root hair cells absorb mineral ions such as nitrates by active transport.
主动运输则逆浓度梯度将物质从低浓度区域移向高浓度区域，需要呼吸作用提供的能量。根毛细胞通过主动运输吸收硝酸盐等矿质离子。
3. Digestive System and Enzymes | 消化系统与酶
The human digestive system is a tube running from the mouth to the anus. Its organs include the mouth, oesophagus, stomach, small intestine, large intestine, rectum, along with accessory glands like the salivary glands, liver and pancreas.
人体消化系统是一条从口腔延伸到肛门的管道，包括口腔、食道、胃、小肠、大肠和直肠，以及唾液腺、肝脏和胰脏等附属腺体。
Digestive enzymes are biological catalysts that break down large insoluble molecules into small soluble ones. Amylase, produced in the salivary glands and pancreas, digests starch into maltose and glucose. Protease, secreted in the stomach and pancreas, breaks down proteins into amino acids. Lipase, produced in the pancreas, digests fats into fatty acids and glycerol. Bile, made in the liver and stored in the gall bladder, emulsifies fats and neutralises stomach acid, creating an alkaline environment for lipase.
消化酶是生物催化剂，可将大分子不溶性物质分解为小分子可溶性物质。淀粉酶由唾液腺和胰腺分泌，将淀粉消化为麦芽糖和葡萄糖。蛋白酶在胃和胰腺中分泌，将蛋白质分解为氨基酸。脂肪酶由胰腺产生，将脂肪分解为脂肪酸和甘油。胆汁由肝脏生成并贮存在胆囊中，能乳化脂肪并中和胃酸，为脂肪酶创造碱性环境。
Enzymes have a specific active site that fits a substrate like a lock and key. High temperatures denature enzymes by changing the shape of the active site, while extremes of pH can also reduce their activity.
酶具有特定的活性位点，与底物就像锁和钥匙一样契合。高温会改变酶活性位点的形状，使酶变性，极端的pH值也会降低酶的活性。
4. Respiratory System and Gas Exchange | 呼吸系统与气体交换
The human respiratory system consists of the trachea, bronchi, bronchioles and alveoli. Breathing involves the contraction and relaxation of the intercostal muscles and diaphragm. During inhalation, the diaphragm contracts and flattens, the intercostal muscles contract to raise the ribcage, and the volume of the thorax increases, lowering the pressure so air rushes into the lungs. Exhalation is largely passive when at rest, with muscles relaxing to push air out.
人体呼吸系统由气管、支气管、细支气管和肺泡组成。呼吸涉及肋间肌和横膈膜的收缩与放松。吸气时，横膈膜收缩变平，肋间肌收缩提升胸腔，胸腔容积增大、压力降低，空气涌入肺部。平静呼气主要为被动过程，肌肉放松将空气推出。
Gas exchange occurs in the alveoli, which are tiny air sacs with walls only one cell thick. They are surrounded by a dense network of capillaries, providing a large surface area and a short diffusion distance. These adaptations allow efficient diffusion of oxygen into the blood and carbon dioxide out of the blood.
气体交换在肺泡中进行，肺泡是壁薄仅单层细胞的微小气囊，被密集的毛细血管网包围，提供了巨大的表面积和极短的扩散距离。这些适应性使氧气能高效地扩散进入血液，二氧化碳从血液中排出。
5. Circulatory System | 循环系统
The circulatory system is responsible for transporting oxygen, nutrients, hormones and waste products around the body. The heart is a muscular organ that pumps blood through a double circulatory system: the right side pumps deoxygenated blood to the lungs (pulmonary circulation), and the left side pumps oxygenated blood to the rest of the body (systemic circulation). The left ventricle has a thicker muscular wall because it must pump blood at higher pressure to the whole body.
循环系统负责将氧气、营养物质、激素和废物输送到全身。心脏是一个肌肉器官，通过双循环系统泵血：右侧将脱氧血泵至肺部（肺循环），左侧将富氧血泵至身体其余部分（体循环）。左心室壁肌肉更厚，因为它需要以更高的压力把血液泵向全身。
Blood flows through three main types of blood vessels. Arteries carry blood away from the heart under high pressure and have thick, elastic walls. Veins return blood to the heart and contain valves to prevent backflow. Capillaries are tiny vessels one cell thick that allow exchange of substances with tissues. Blood consists of red blood cells (carrying oxygen using haemoglobin), white blood cells (fighting infection), platelets (clotting) and plasma (transporting dissolved substances).
血液流过三种主要血管。动脉将血液从心脏高压输出，管壁厚而有弹性。静脉将血液送回心脏，含有防止回流的瓣膜。毛细血管是壁仅一细胞厚的微小血管，能与组织进行物质交换。血液包括红细胞（利用血红蛋白运输氧气）、白细胞（抗感染）、血小板（凝血）和血浆（运输溶解物质）。
6. Nervous System and Hormones | 神经系统与激素
The nervous system uses electrical impulses to bring about rapid, short-lived responses. A reflex arc is the simplest pathway: a stimulus is detected by a receptor, and an impulse travels along a sensory neuron to the spinal cord, across a synapse to a relay neuron, then to a motor neuron, which stimulates an effector (muscle or gland) to respond. Synapses are gaps where chemical neurotransmitters transmit signals.
神经系统利用电冲动引发快速而短暂的响应。反射弧是最简单的通路：感受器检测刺激，冲动沿感觉神经元传到脊髓，通过突触传递到中间神经元，再到运动神经元，刺激效应器（肌肉或腺体）作出反应。突触是间隙，依靠化学神经递质传递信号。
Hormones are chemical messengers produced by endocrine glands and carried in the blood. Compared with nerve impulses, hormonal responses are slower but longer lasting. Insulin, produced by the pancreas, lowers blood glucose levels by converting glucose to glycogen in the liver. Adrenaline prepares the body for ‘fight or flight’ by increasing heart rate and diverting blood to muscles.
激素是由内分泌腺产生并由血液运输的化学信使。与神经冲动相比，激素反应较慢但持续时间更长。胰腺产生的胰岛素通过将葡萄糖转化为肝糖原降低血糖水平。肾上腺素使身体做好“战斗或逃跑”的准备，加快心率并将血液重新分配到肌肉。
7. Photosynthesis | 光合作用
Photosynthesis is the process by which green plants and some other organisms use light energy to convert carbon dioxide and water into glucose and oxygen. The overall word equation is:
光合作用是绿色植物及某些其他生物利用光能将二氧化碳和水转化为葡萄糖和氧气的过程。总文字方程式为：
carbon dioxide + water → glucose + oxygen
In the presence of light and chlorophyll, the balanced chemical equation is: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂.
在光照和叶绿素存在下，平衡化学方程式为：6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂。
Photosynthesis is a two-stage process. Light energy is absorbed by chlorophyll in the chloroplasts to split water molecules, releasing oxygen. The energy is then used to convert carbon dioxide into glucose, which can be stored as starch or used in respiration. The rate of photosynthesis is affected by limiting factors: light intensity, carbon dioxide concentration and temperature. At a given point, only one factor limits the rate.
光合作用分为两个阶段。叶绿体中的叶绿素吸收光能，分解水分子并释放氧气。随后利用能量将二氧化碳转化为葡萄糖，葡萄糖可以淀粉形式储存或用于呼吸。光合作用速率受限制因素影响：光照强度、二氧化碳浓度和温度。在任一时刻，只有一个因素会限制速率。
8. Aerobic and Anaerobic Respiration | 有氧呼吸与无氧呼吸
Respiration is the release of energy from food molecules, such as glucose, to supply ATP for cellular activities. It occurs in all living cells continuously.
呼吸作用是从食物分子（如葡萄糖）中释放能量，为细胞活动提供ATP的过程，在所有活细胞中持续进行。
Aerobic respiration uses oxygen to fully break down glucose, releasing a large amount of energy. The balanced equation is: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O (+ energy as ATP). This takes place in mitochondria.
有氧呼吸利用氧气将葡萄糖彻底分解，释放大量能量。平衡方程式为：C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O (+ 以ATP形式的能量)，此过程在线粒体中进行。
Anaerobic respiration occurs when oxygen is insufficient. In animal cells, glucose is partially broken down into lactic acid: glucose → lactic acid (+ some energy). In yeast and some plants, anaerobic respiration produces ethanol and carbon dioxide: glucose → ethanol + carbon dioxide (+ some energy). Anaerobic respiration yields far less ATP than aerobic respiration and can lead to an oxygen debt in muscles, which is repaid by deep breathing after exercise.
当氧气不足时会发生无氧呼吸。在动物细胞中，葡萄糖被不完全分解产生乳酸：葡萄糖 → 乳酸 (+ 少量能量)。在酵母和某些植物中，无氧呼吸产生乙醇和二氧化碳：葡萄糖 → 乙醇 + 二氧化碳 (+ 少量能量)。无氧呼吸产生的ATP远少于有氧呼吸，并且会在肌肉中造成氧债，运动后通过深呼吸偿还。
9. Ecology and Energy Flow | 生态学与能量流动
Ecology studies the interactions between organisms and their environment. A food chain shows the transfer of energy from producers (plants and algae) to primary consumers, secondary consumers and so on. Arrows represent the direction of energy flow. Decomposers break down dead organisms, recycling nutrients back into the ecosystem.
生态学研究生物与环境之间的相互作用。食物链表示能量从生产者（植物和藻类）传递到初级消费者、次级消费者等的过程，箭头代表能量流动的方向。分解者分解死去的生物体，将营养物循环回生态系统。
In a food web, organisms may occupy multiple trophic levels. Energy is lost at each level through respiration, heat, movement and undigested food, so biomass pyramids are typically pyramid-shaped. Only about 10% of energy is passed from one trophic level to the next.
在食物网中，生物可能占据多个营养级。能量在每一级都通过呼吸、散热、运动和未消化食物而损失，因此生物量金字塔通常呈金字塔形。只有约10%的能量从一个营养级传递到下一个营养级。
The carbon cycle describes how carbon atoms are recycled through photosynthesis, respiration, combustion and decomposition. The water cycle involves evaporation, condensation, precipitation and transpiration. Studying ecosystems requires sampling techniques such as quadrats for plant distribution and transect lines to measure changes across a habitat. Biotic and abiotic factors, including competition, disease, temperature and soil pH, influence population sizes.
碳循环描述了碳原子如何通过光合作用、呼吸作用、燃烧和分解而循环。水循环包括蒸发、凝结、降水和蒸腾作用。研究生态系统需要使用采样技术，如用样方调查植物分布，用样线测量栖息地变化。生物和非生物因素，包括竞争、疾病、温度和土壤pH值，都会影响种群大小。
10. Genetics and Evolution | 遗传学与进化
DNA is a double-helix molecule that carries genetic information. A gene is a section of DNA that codes for a particular protein. Alleles are different versions of the same gene. An organism with two identical alleles for a trait is homozygous; if the alleles are different, it is heterozygous. A dominant allele will express its characteristic even if only one copy is present; a recessive allele only shows in the phenotype when two copies are present.
DNA是携带遗传信息的双螺旋分子。基因是编码特定蛋白质的一段DNA。等位基因是同一基因的不同形式。生物某个性状的两个等位基因相同则为纯合子，不同则为杂合子。显性等位基因即使只有一个拷贝也会表达性状，隐性等位基因只有存在两个拷贝时才会在表现型中显现。
Monohybrid crosses can predict the probability of offspring inheriting certain traits. For example, crossing two heterozygous parents (Aa × Aa) produces offspring with a 3:1 ratio of dominant to recessive phenotypes, assuming complete dominance.
单基因杂交能预测后代继承特定性状的概率。例如，两个杂合亲本杂交（Aa × Aa），在所有完全显性假设下，后代表现型显性与隐性比例为3:1。
Evolution by natural selection occurs when there is genetic variation within a population, a struggle for survival, and individuals with advantageous alleles are more likely to survive and reproduce. Over generations, the frequency of these alleles increases. Antibiotic resistance in bacteria is a rapid form of evolution: a chance mutation may confer resistance, and the use of antibiotics kills non-resistant strains, leaving resistant bacteria to multiply and pass on the resistance allele.
自然选择导致的进化发生在种群存在遗传变异、生存斗争激烈之时，拥有有利等位基因的个体更可能存活并繁殖。经若干世代，这些等位基因的频率上升。细菌的抗生素耐药性是一种快速进化形式：偶然突变可能赋予耐药性，抗生素的使用杀死了非耐药菌株，耐药的细菌得以繁殖并将耐药等位基因传递下去。
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