📚 Year 13 Edexcel Biology: Core Knowledge Points Review | 核心知识点梳理
Welcome to our comprehensive review of the most important knowledge points for Year 13 Edexcel Biology. This article summarises key concepts across topics including energy transfer, photosynthesis, respiration, homeostasis, nervous coordination, immunology, genetic engineering, gene expression, evolution and more. Use this as a checklist to reinforce your understanding and boost your exam readiness.
欢迎阅读我们为 Year 13 Edexcel 生物学科梳理的核心知识点综述。本文总结了能量传递、光合作用、呼吸作用、稳态调节、神经协调、免疫学、基因工程、基因表达与进化等模块的关键概念。您可以把这篇文章当作一份巩固理解、提升应试状态的复习清单。
1. Photosynthesis | 光合作用
Photosynthesis consists of two main stages: the light-dependent reactions take place in the thylakoid membranes and produce ATP and reduced NADP; the light-independent reactions (Calvin cycle) occur in the stroma and use ATP and reduced NADP to fix CO₂ into sugars such as triose phosphate.
光合作用包含两个主要阶段：光依赖反应在类囊体膜上进行，生成 ATP 和还原型 NADP；光不依赖反应（卡尔文循环）发生在基质中，利用 ATP 和还原型 NADP 将 CO₂ 固定为磷酸丙糖等糖类。
Non-cyclic photophosphorylation involves both photosystem I (PSI) and photosystem II (PSII), splitting water (photolysis) to release O₂, and producing ATP and reduced NADP. Cyclic photophosphorylation uses only PSI, generating ATP without producing reduced NADP or O₂.
非循环光合磷酸化涉及光系统 I（PSI）和光系统 II（PSII），水光解释放 O₂，并产生 ATP 和还原型 NADP。循环光合磷酸化仅利用 PSI，只产生 ATP，不产生还原型 NADP 和 O₂。
The rate of photosynthesis is limited by light intensity, CO₂ concentration and temperature. At low light, the light-dependent reactions limit the rate; at high light, the Calvin cycle or stomatal closure may become limiting. The compensation point occurs when photosynthetic O₂ production equals respiratory O₂ consumption.
光合作用速率受光照强度、CO₂ 浓度和温度的限制。在弱光下，光依赖反应限速；在强光下，卡尔文循环或气孔关闭可能成为限制因素。补偿点是指光合产氧量与呼吸耗氧量相等时的状态。
2. Energy Transfer and Productivity | 能量传递与生产力
In food chains, energy is transferred from one trophic level to the next, but typically only about 10% of the energy is passed on. Most energy is lost through metabolic heat, uneaten materials, egestion and excretion. This pyramid-shaped energy distribution explains why food chains rarely have more than four or five trophic levels.
在食物链中，能量从一个营养级传递至下一个营养级，但通常只有约 10% 的能量被传递。大部分能量通过代谢产热、未被取食的物质、排遗和排泄而损失。这种金字塔形的能量分布解释了为什么食物链很少超过四到五个营养级。
Gross primary productivity (GPP) is the total chemical energy captured by producers via photosynthesis. Net primary productivity (NPP) is the energy remaining after respiratory losses: NPP = GPP − respiration. Ecological efficiency can be calculated as (energy transferred / energy available) × 100%.
总初级生产力（GPP）是生产者通过光合作用固定的化学能总量。净初级生产力（NPP）是扣除呼吸损耗后剩余的能量：NPP = GPP − 呼吸消耗。生态效率可计算为（传递的能量 / 可用的能量）× 100%。
Intensive farming methods, such as restricting movement of livestock and using high-energy feed, reduce respiratory losses and increase the proportion of energy converted into biomass. However, these practices raise ethical concerns and can lead to environmental problems like pollution and reduced biodiversity.
集约农业措施（例如限制家畜活动和饲喂高能饲料）减少了呼吸损耗，提高了能量转化为生物量的比例。但这些做法引发伦理关切，并可能导致污染和生物多样性下降等环境问题。
3. Cellular Respiration | 细胞呼吸
Glycolysis occurs in the cytoplasm. Glucose is phosphorylated using ATP, split into two triose phosphate molecules, then oxidised to pyruvate. This yields a net gain of 2 ATP and 2 reduced NAD per glucose.
糖酵解发生在细胞质中。葡萄糖被 ATP 磷酸化，裂解为两个磷酸丙糖分子，再氧化为丙酮酸。每分子葡萄糖净生成 2 个 ATP 和 2 个还原型 NAD。
The link reaction transports pyruvate into the mitochondrial matrix, where it is decarboxylated and oxidised to form acetyl coenzyme A (acetyl-CoA). The Krebs cycle then oxidises acetyl-CoA completely, producing 2 CO₂, 1 ATP (via GTP), 3 reduced NAD and 1 reduced FAD per turn.
连接反应将丙酮酸转运到线粒体基质，在此脱羧并氧化形成乙酰辅酶 A。克雷布斯循环随后将乙酰辅酶 A 彻底氧化，每圈生成 2 CO₂、1 ATP（经由 GTP）、3 个还原型 NAD 和 1 个还原型 FAD。
Oxidative phosphorylation uses the electron transport chain on the inner mitochondrial membrane. Reduced coenzymes donate electrons, which pass through a series of carriers, pumping protons into the intermembrane space. The proton gradient drives ATP synthase (chemiosmosis). O₂ acts as the final electron acceptor, forming water.
氧化磷酸化借助于线粒体内膜上的电子传递链。还原型辅酶提供电子，电子经一系列载体传递，将质子泵入膜间隙。质子梯度驱动 ATP 合酶（化学渗透）。O₂ 是最终电子受体，生成水。
4. Homeostasis and Feedback Mechanisms | 稳态与反馈机制
Homeostasis is maintained by negative feedback systems, which reverse a deviation from a set point. Blood glucose regulation exemplifies this: when glucose rises, β cells in the pancreas secrete insulin, promoting glycogen synthesis and glucose uptake; when glucose falls, α cells secrete glucagon, stimulating glycogenolysis and gluconeogenesis.
稳态由负反馈系统维持，该系统逆转偏离调定点的变化。血糖调节是典型实例：血糖升高时，胰岛 β 细胞分泌胰岛素，促进糖原合成和葡萄糖摄取；血糖降低时，α 细胞分泌胰高血糖素，刺激糖原分解和糖异生。
Positive feedback amplifies a change, such as the release of oxytocin during childbirth. Pressure of the baby’s head against the cervix stimulates more oxytocin secretion, intensifying uterine contractions until birth occurs.
正反馈会放大变化，例如分娩时催产素的释放。婴儿头部对宫颈的压迫刺激更多的催产素分泌，从而加强宫缩，直至胎儿娩出。
Thermoregulation involves the hypothalamus co-ordinating responses to maintain core temperature. In cold conditions, skin arterioles constrict, piloerection occurs, and shivering generates heat. In hot conditions, vasodilation and sweating promote heat loss.
体温调节由下丘脑协调响应以维持体核温度。寒冷时，皮肤小动脉收缩、毛发竖立、颤抖产热；炎热时，血管舒张和出汗促进散热。
5. Nervous Coordination and Muscles | 神经协调与肌肉
The resting potential of a neurone (-70 mV) is established by the Na⁺/K⁺ pump, which actively transports 3 Na⁺ out and 2 K⁺ in, and by the greater permeability of the membrane to K⁺, allowing K⁺ to leak out. During an action potential, voltage-gated Na⁺ channels open, causing rapid depolarisation; the subsequent opening of K⁺ channels repolarises the membrane.
神经元的静息电位（-70 mV）由 Na⁺/K⁺ 泵（主动转运 3 个 Na⁺ 出胞、2 个 K⁺ 入胞）以及膜对 K⁺ 较高的通透性（K⁺ 漏出）共同建立。动作电位发生时，电压门控 Na⁺ 通道开放，引起快速去极化；随后 K⁺ 通道开放使膜复极化。
At a synapse, an arriving action potential opens voltage-gated Ca²⁺ channels in the presynaptic knob. Ca²⁺ influx triggers synaptic vesicles to fuse with the membrane and release neurotransmitter (e.g. acetylcholine). Neurotransmitter binds to receptors on the postsynaptic membrane, opening ligand-gated ion channels and generating excitatory or inhibitory postsynaptic potentials.
在突触处，到达的动作电位打开突触前小结中的电压门控 Ca²⁺ 通道。Ca²⁺ 内流触发突触小泡与膜融合，释放神经递质（如乙酰胆碱）。神经递质与突触后膜上的受体结合，开放配体门控离子通道，产生兴奋性或抑制性突触后电位。
Skeletal muscle contraction follows the sliding filament theory. Ca²⁺ binds to troponin, causing tropomyosin to move away from myosin-binding sites on actin. Myosin heads form cross-bridges, perform a power stroke, and then detach using ATP, pulling the actin filaments towards the sarcomere centre.
骨骼肌收缩遵循滑动丝模型。Ca²⁺ 与肌钙蛋白结合，使原肌球蛋白从肌动蛋白上的肌球蛋白结合位点移开。肌球蛋白头形成横桥，执行力量冲程，然后利用 ATP 解脱，将肌动蛋白丝拉向肌节中心。
6. The Brain and Visual Development | 大脑与视觉发育
The human brain contains several specialised regions: the cerebrum (with sensory, motor and association areas), the cerebellum controlling balance and fine movement, the hypothalamus regulating homeostasis, and the medulla oblongata governing autonomic functions. Functional magnetic resonance imaging (fMRI) detects brain activity by measuring changes in blood flow.
人脑包含多个特化区域：大脑（含感觉区、运动区和联络区），控制平衡和精细运动的小脑，调节稳态的下丘脑，以及掌控自主功能的延髓。功能性磁共振成像（fMRI）通过测量血流变化来检测脑活动。
The development of the visual cortex relies on visual experience during a critical period. Hubel and Wiesel’s classic experiments on kittens showed that monocular deprivation during the critical period leads to permanent loss of ocular dominance columns for the deprived eye, while the columns of the open eye expand.
视觉皮层的发育依赖于关键期内的视觉体验。Hubel 和 Wiesel 对幼猫的经典实验表明，在关键期内进行单眼剥夺会导致被剥夺眼对应的眼优势柱永久丧失，而开放眼的优势柱相应扩展。
Brain plasticity – the ability of the brain to reorganise itself by forming new neural connections – is retained to some degree in adults but is greatest during early childhood. MRI studies reveal how learning and injury can alter brain structure.
脑可塑性——大脑通过形成新神经连接而进行自身重组的能力——在成年人中仍保留一定程度，但在儿童早期最为显著。MRI 研究展示了学习和损伤如何改变脑结构。
7. Immunology and Diseases | 免疫学与疾病
Non-specific defences include physical barriers like skin and mucous membranes, phagocytosis by neutrophils and macrophages, and the inflammatory response. Histamine release causes vasodilation and increased capillary permeability, aiding the recruitment of immune cells.
非特异性防御包括皮肤和粘膜等物理屏障、中性粒细胞和巨噬细胞的吞噬作用以及炎症反应。组胺释放导致血管舒张和毛细血管通透性增加，有助于招募免疫细胞。
Specific immune responses involve T lymphocytes and B lymphocytes. Helper T cells have CD4 receptors and, upon activation, release cytokines that stimulate B cells to proliferate and differentiate into plasma cells, and activate cytotoxic T cells (CD8+). Clonal selection ensures that only the lymphocytes with the correct receptor are expanded, and memory cells are retained for a faster secondary response.
特异性免疫应答涉及 T 淋巴细胞和 B 淋巴细胞。辅助 T 细胞具有 CD4 受体，活化后释放细胞因子，刺激 B 细胞增殖分化为浆细胞，并激活细胞毒性 T 细胞（CD8+）。克隆选择确保只有携带正确受体的淋巴细胞被扩增，记忆细胞被保留以实现更快的二次应答。
Active immunity results from exposure to an antigen, whether through infection or vaccination; passive immunity involves the transfer of antibodies (e.g. maternal antibodies or monoclonal antibodies). Vaccination programmes aim to establish herd immunity. Antibiotic resistance arises when bacteria with resistance alleles survive and reproduce under selective pressure.
主动免疫由接触抗原（感染或疫苗接种）产生；被动免疫涉及抗体的转移（如母源抗体或单克隆抗体）。疫苗接种计划旨在建立群体免疫。当携带耐药等位基因的细菌在选择压力下存活并繁殖时，抗生素耐药性便产生。
8. Genetic Engineering and DNA Analysis | 基因工程与 DNA 分析
Recombinant DNA technology uses restriction endonucleases to cut DNA at specific recognition sites, generating sticky or blunt ends. DNA ligase joins the insulin gene (or other target gene) into a plasmid vector. The recombinant plasmid is then introduced into host bacteria by transformation, which are cultured to produce the protein.
重组 DNA 技术利用限制性内切酶在特定识别位点切割 DNA，产生黏性末端或平末端。DNA 连接酶将胰岛素基因（或其他目的基因）连接到质粒载体中。重组质粒通过转化导入宿主细菌，经培养即可生产目标蛋白。
The polymerase chain reaction (PCR) amplifies DNA in vitro. It involves repeated cycles of denaturation (95 °C), primer annealing (55–65 °C), and extension by Taq polymerase (72 °C). Gel electrophoresis separates DNA fragments by size; negatively charged DNA moves towards the positive electrode and smaller fragments travel faster.
聚合酶链式反应（PCR）在体外扩增 DNA。它包括变性（95 °C）、引物退火（55–65 °C）和 Taq 聚合酶延伸（72 °C）的反复循环。凝胶电泳根据大小分离 DNA 片段；带负电的 DNA 向正极移动，较小的片段迁移更快。
DNA profiling analyses short tandem repeats (STRs) found at specific loci. By comparing the pattern of STR bands, forensic scientists can match crime scene samples to suspects, and paternity disputes can be resolved by identifying shared alleles between child and alleged parent.
DNA 指纹分析检测特定位点上的短串联重复序列（STR）。通过比对 STR 条带模式，法医可以将犯罪现场样本与嫌疑人匹配，而亲子鉴定则通过识别孩子和疑父共有的等位基因来解决争议。
9. Gene Expression and Epigenetics | 基因表达与表观遗传学
Transcription factors are proteins that bind to specific DNA sequences (e.g. promoter regions) to control the rate of transcription. Some hormones, such as oestrogen, diffuse through the cell membrane, bind to intracellular receptors, form a complex that enters the nucleus and acts as a transcription factor, switching on target genes.
转录因子是结合特定 DNA 序列（如启动子区域）以控制转录速率的蛋白质。某些激素（如雌激素）穿透细胞膜，与胞内受体结合，形成的复合物进入细胞核，作为转录因子开启靶基因。
Small interfering RNA (siRNA) mediates RNA interference. Double-stranded RNA is cut by the enzyme Dicer into siRNA, which then associates with the RISC complex. The siRNA guide strand binds to complementary mRNA, leading to its cleavage and degradation, preventing translation.
小干扰 RNA（siRNA）介导 RNA 干扰。双链 RNA 被 Dicer 酶切割成 siRNA，随后与 RISC 复合物结合。siRNA 的引导链与互补 mRNA 结合，导致其切割和降解，从而阻止翻译。
Epigenetic changes alter gene expression without
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