📚 Key Concepts Revision for Year 13 Edexcel Biology | Year 13 Edexcel 生物：核心知识点梳理
Welcome to your essential Year 13 Edexcel Biology revision guide. We have distilled the core topics into concise bilingual sections, ensuring you master both the English scientific terminology and the underlying concepts. Use this resource to solidify your understanding of photosynthesis, respiration, genetics, neurobiology, and much more.
欢迎使用 Year 13 Edexcel 生物精选复习指南。我们将核心主题浓缩为中英双语小节，帮助您同时掌握英文科学术语和深层概念。利用本文巩固您对光合作用、细胞呼吸、遗传学、神经生物学等重要内容的理解。
1. Photosynthesis and Energy Conversion | 光合作用与能量转化
The light-dependent reactions take place in the thylakoid membranes. Light energy is absorbed by chlorophyll, exciting electrons that move along the electron transport chain. Photolysis of water generates protons, electrons, and oxygen; the energy released is used to produce ATP via chemiosmosis and to reduce NADP⁺ to NADPH.
光反应发生在类囊体膜上。叶绿素吸收光能，激发电子沿电子传递链移动。水的光解产生质子、电子和氧气；释放的能量通过化学渗透生成 ATP，并将 NADP⁺ 还原为 NADPH。
In the light-independent stage (Calvin cycle) in the stroma, the enzyme RuBisCO catalyses the fixation of CO₂ to ribulose bisphosphate (RuBP). Using ATP and NADPH from the light reactions, the cycle produces triose phosphate, which is then used to synthesise glucose, starch, and other organic molecules.
在基质中进行的光反应非依赖阶段（卡尔文循环）中，酶 RuBisCO 催化 CO₂ 固定到核酮糖二磷酸 (RuBP) 上。利用光反应提供的 ATP 和 NADPH，该循环生成磷酸丙糖，后者进一步合成葡萄糖、淀粉和其他有机分子。
Key limiting factors include light intensity, carbon dioxide concentration, and temperature. At low light intensities, photosynthesis is light-limited; at high CO₂ levels, the Calvin cycle is favoured until another factor becomes limiting.
主要的限制因素包括光照强度、二氧化碳浓度和温度。在低光照强度下，光合作用受光限制；在高 CO₂ 条件下，卡尔文循环速率提高，直到另一个因素成为瓶颈。
2. Cellular Respiration and ATP Synthesis | 细胞呼吸与 ATP 合成
Glycolysis occurs in the cytoplasm, splitting one glucose molecule (6C) into two pyruvate molecules (3C). This process produces a net gain of 2 ATP and 2 reduced NAD⁺.
糖酵解在细胞质中进行，将一分子葡萄糖 (6C) 分解为两分子丙酮酸 (3C)。该过程净生成 2 个 ATP 和 2 个还原型 NAD⁺。
In aerobic conditions, pyruvate enters the mitochondrial matrix, where the link reaction decarboxylates it to acetyl coenzyme A, producing reduced NAD⁺ and releasing CO₂. The Krebs cycle then oxidises acetyl CoA completely to CO₂, generating reduced NAD⁺, reduced FAD, and ATP.
在有氧条件下，丙酮酸进入线粒体基质，在连接反应中脱羧生成乙酰辅酶 A，同时产生还原型 NAD⁺ 并释放 CO₂。克雷布斯循环随后将乙酰辅酶 A 彻底氧化为 CO₂，生成还原型 NAD⁺、还原型 FAD 和 ATP。
Oxidative phosphorylation on the inner mitochondrial membrane uses the electron transport chain and chemiosmosis. Reduced coenzymes donate electrons, driving proton pumping; the proton gradient powers ATP synthase. Oxygen acts as the final electron acceptor, forming water.
线粒体内膜上的氧化磷酸化通过电子传递链和化学渗透作用进行。还原型辅酶提供电子，驱动质子泵；质子梯度驱动 ATP 合酶合成 ATP。氧气作为最终电子受体，生成水。
Anaerobic respiration in animals converts pyruvate to lactate, regenerating NAD⁺ for glycolysis. In yeast, pyruvate is decarboxylated to ethanol and CO₂, also regenerating NAD⁺.
动物中的无氧呼吸将丙酮酸转化为乳酸，再生 NAD⁺ 用于糖酵解。酵母中，丙酮酸脱羧生成乙醇和 CO₂，同样再生 NAD⁺。
3. Energy Flow and Nutrient Cycling in Ecosystems | 生态系统的能量流动与养分循环
after plant respiration: NPP = GPP − R. NPP is the energy available to primary consumers.
总初级生产力 (GPP) 是光合作用固定的化学能总量。净初级生产力 (NPP) 是扣除植物呼吸消耗后剩余的能量：NPP = GPP − R。NPP 是可供初级消费者利用的能量。
Energy transfer between trophic levels is inefficient — typically only about 10% is passed on. Losses occur through heat, respiration, movement, and undigested matter. Ecological pyramids illustrate this progressive energy loss.
营养级之间的能量传递效率很低，通常只有约 10% 的能量向上传递。能量损失途径包括散热、呼吸作用、运动以及未被消化的物质。生态金字塔形象地展示了这种逐级递减的能量流。
The carbon cycle involves photosynthesis fixing atmospheric CO₂ into organic carbon, and respiration, combustion, and decomposition returning CO₂ to the atmosphere. Microorganisms play a crucial role in decomposition and mineralisation.
碳循环中，光合作用将大气 CO₂ 固定为有机碳，而呼吸作用、燃烧和分解作用将 CO₂ 归还大气。微生物在有机物质的分解和矿化过程中发挥着关键作用。
4. Genetics: Inheritance Patterns and Statistical Testing | 遗传学：遗传规律与统计检验
Monohybrid and dihybrid crosses follow Mendelian ratios, but deviations occur due to linkage, sex linkage, and epistasis. Linked genes are located close together on the same chromosome and tend to be inherited together, reducing recombinant phenotypes.
单因子和双因子杂交遵循孟德尔比率，但连锁、性连锁和上位性会导致偏离。连锁基因位于同一条染色体上且位置接近，倾向于共同遗传，从而减少了重组表型的出现。
Sex linkage is observed when the gene is located on the X chromosome; males are more frequently affected by recessive X-linked disorders because they are hemizygous. Epistasis occurs when one gene masks the expression of another, often through interacting enzyme pathways.
当基因位于 X 染色体上时，表现为性连锁遗传；男性由于是半合子，因此更易表现出隐性 X 连锁疾病。上位性是一个基因掩盖另一个基因的表达，常通过相互作用的酶通路实现。
The chi-squared test compares observed phenotypic ratios with expected ratios to determine whether differences are due to chance. A significant result suggests that the data do not fit the expected Mendelian inheritance pattern.
卡方检验将观察到的表型比率与预期比率进行比较，以判断差异是否由偶然因素导致。显著性差异表明实验数据不符合预期的孟德尔遗传模式。
5. Gene Expression and Epigenetic Control | 基因表达与表观遗传调控
Transcription factors control which genes are transcribed in a particular cell. In eukaryotes, activators and repressors bind to promoter regions and enhancers, facilitating or inhibiting RNA polymerase binding.
转录因子调控特定细胞中哪些基因被转录。在真核生物中，激活因子和抑制因子与启动子区和增强子结合，促进或抑制 RNA 聚合酶的结合。
Epigenetics involves heritable changes in gene function that do not alter the DNA sequence. DNA methylation typically silences transcription, while histone acetylation loosens chromatin structure and promotes gene expression.
表观遗传学涉及不改变 DNA 序列的可遗传的基因功能变化。DNA 甲基化通常使转录沉默，而组蛋白乙酰化松弛染色质结构，促进基因表达。
RNA interference (RNAi) is a post-transcriptional mechanism in which small interfering RNA (siRNA) binds to complementary mRNA, leading to its degradation by the RISC complex. This effectively prevents translation of the target gene.
RNA 干扰 (RNAi) 是一种转录后调控机制，小干扰 RNA (siRNA) 与互补的 mRNA 结合，引导 RISC 复合体将其降解，从而有效阻止靶基因的翻译。
6. DNA Profiling, PCR, and Forensic Applications | DNA 图谱、PCR 与法医学应用
The polymerase chain reaction (PCR) amplifies specific DNA sequences in vitro. Each cycle involves denaturation (95 °C), primer annealing (55-65 °C), and extension by Taq polymerase (72 °C). Exponential amplification generates millions of copies.
聚合酶链式反应 (PCR) 在体外扩增特定的 DNA 序列。每个循环包括变性 (95 °C)、引物退火 (55–65 °C) 和 Taq 聚合酶延伸 (72 °C)。指数级扩增产生数百万个拷贝。
Gel electrophoresis separates DNA fragments by size. Samples are loaded into an agarose gel and subjected to an electric field; shorter fragments migrate faster toward the anode. DNA profiles reveal patterns of short tandem repeats (STRs) used in identification.
凝胶电泳根据大小分离 DNA 片段。样品加载到琼脂糖凝胶中并施加电场，较短片段向阳极迁移得更快。DNA 图谱显示短串联重复序列 (STR) 的模式，常用于身份鉴定。
DNA profiling is used in forensic science to compare crime scene samples with suspects, and in paternity testing. The probability of a random match is extremely low, making it a powerful tool when combined with statistical analysis.
DNA 图谱分析用于法医学，将犯罪现场样本与嫌疑人进行比对，也可用于亲子鉴定。随机匹配概率极低，当与统计分析结合时，成为一种强有力的工具。
7. Nervous Coordination and Muscle Contraction | 神经协调与肌肉收缩
An action potential is generated when a stimulus depolarises the membrane to threshold, opening voltage-gated Na⁺ channels. The influx of Na⁺ causes rapid depolarisation; repolarisation follows as K⁺ channels open and Na⁺ channels inactivate.
刺激使膜去极化达到阈电位时，电压门控 Na⁺ 通道开放，产生动作电位。Na⁺ 内流导致快速去极化；随后 K⁺ 通道开放，Na⁺ 通道失活，发生复极化。
Synaptic transmission involves the arrival of an action potential at the presynaptic terminal, triggering Ca²⁺ influx and exocytosis of neurotransmitter vesicles. The neurotransmitter diffuses across the synaptic cleft and binds receptors on the postsynaptic membrane, potentially generating a new action potential.
突触传递包括动作电位到达突触前末梢，触发 Ca²⁺ 内流和神经递质囊泡的胞吐作用。神经递质扩散通过突触间隙，与突触后膜受体结合，可能引发新的动作电位。
Skeletal muscle contraction is explained by the sliding filament model. Ca²⁺ released from the sarcoplasmic reticulum binds to troponin, shifting tropomyosin to expose myosin-binding sites on actin. Myosin heads form cross-bridges, pulling actin filaments and shortening the sarcomere, powered by ATP hydrolysis.
骨骼肌收缩可用滑动丝模型解释。从肌质网释放的 Ca²⁺ 与肌钙蛋白结合，使原肌球蛋白移动，暴露出肌动蛋白上的肌球蛋白结合位点。肌球蛋白头形成横桥，牵引肌动蛋白丝，使肌小节缩短，该过程由 ATP 水解提供能量。
8. Homeostasis and Hormonal Control | 稳态与激素调控
Homeostasis is maintained through negative feedback mechanisms. A deviation from the set point triggers a response that reverses the change, ensuring a stable internal environment for enzyme activity and cellular function.
稳态通过负反馈机制维持。偏离设定点会触发逆向调节的应答，确保内环境稳定，以利于酶活性和细胞功能。
Blood glucose regulation involves insulin and glucagon. When blood glucose rises, pancreatic β-cells secrete insulin, promoting glucose uptake and glycogenesis. When glucose falls, α-cells release glucagon, stimulating glycogenolysis and gluconeogenesis.
血糖调节涉及胰岛素和胰高血糖素。血糖升高时，胰腺 β 细胞分泌胰岛素，促进葡萄糖摄取和糖原合成。血糖降低时，α 细胞释放胰高血糖素，刺激肝糖原分解和糖异生。
Osmoregulation is controlled by ADH. When blood water potential decreases, osmoreceptors in the hypothalamus trigger ADH release from the posterior pituitary. ADH increases the permeability of collecting duct cells to water, enhancing reabsorption and producing concentrated urine.
渗透调节由抗利尿激素 (ADH) 控制。血液水势下降时，下丘脑的渗透压感受器触发垂体后叶释放 ADH。ADH 增加集合管细胞对水的通透性，加强重吸收，产生浓缩尿。
9. Plant Responses to Light and Gravity | 植物对光和重力的响应
Phototropisms are directional growth responses to light, mediated by the plant hormone indole-3-acetic acid (IAA). IAA accumulates on the shaded side of a shoot, stimulating cell elongation and causing the shoot to bend toward the light.
向光性是植物对光的定向生长反应，由植物激素吲哚-3-乙酸 (IAA) 介导。IAA 在茎的背光侧积累，刺激细胞伸长，导致茎向光弯曲。
Gravitropism involves the redistribution of IAA in roots and shoots. In roots, high IAA concentration inhibits cell elongation on the lower side, causing the root to bend downward. In shoots, high IAA on the lower side promotes elongation and upward bending.
向重力性涉及 IAA 在根和茎中的重新分布。在根中，高浓度 IAA 抑制下侧细胞伸长，使根向下弯曲。在茎中，下侧的高浓度 IAA 促进细胞伸长，导致茎向上弯曲。
Phytochromes are photoreceptors that detect red and far-red light, controlling seed germination, flowering, and shade avoidance. The conversion between Pr and Pfr forms enables plants to sense day length.
光敏色素是感知红光和远红光的受体，调控种子萌发、开花和避荫反应。Pr 与 Pfr 两种形式的转换使植物能够感知昼夜长短。
10. Gene Technology and Ethical Issues | 基因技术与伦理议题
Genetic engineering involves the transfer of target genes using vectors such as plasmids. Restriction endonucleases cut DNA at specific recognition sites, producing sticky ends. DNA ligase joins the gene of interest to the vector, creating recombinant DNA.
基因工程使用质粒等载体转移目标基因。限制性内切酶在特定识别位点切割 DNA，产生粘性末端。DNA 连接酶将目的基因与载体连接，形成重组 DNA。
Gene therapy aims to treat genetic disorders by inserting a normal allele into a patient's cells. Vectors such as modified viruses deliver the functioning gene into somatic cells, but challenges remain regarding immune response and long-term expression.
基因治疗旨在通过将正常等位基因插入患者细胞来治疗遗传疾病。载体（如改造的病毒）将功能性基因递送到体细胞中，但免疫反应和长期表达仍是挑战。
Genetically modified organisms (GMOs), particularly crops, are engineered for traits like pest resistance and herbicide tolerance. Ethical concerns include potential ecological impacts, gene flow to wild relatives, and the right to patent life forms.
转基因生物 (GMO)，尤其是转基因作物，被赋予抗虫、抗除草剂等性状。伦理问题包括潜在的生态影响、基因流向野生近缘种以及生命形式的专利权争议。
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