📚 Year 13 AQA Biology: Core Concepts Summarized | 核心知识点梳理
Year 13 AQA Biology builds on AS knowledge to explore the intricate processes that sustain life, from the molecular dance of photosynthesis and respiration to the complex orchestration of nervous coordination and gene expression. This revision guide distils the core topics into concise, bilingual summaries, helping you reinforce key ideas, connect concepts, and prepare effectively for your exams.
AQA 生物 Year 13 课程在 AS 基础上深入探索维持生命的精妙过程，从光合作用与呼吸作用的分子律动，到神经系统协调与基因表达的复杂调控。这篇双语复习指南将核心主题浓缩为简洁的要点梳理，帮助你巩固关键概念、建立跨主题联系，高效备战考试。
1. Photosynthesis | 光合作用
Photosynthesis occurs in chloroplasts and converts light energy into chemical energy stored in glucose. It consists of two stages: the light-dependent reaction on the thylakoid membranes and the light-independent reaction (Calvin cycle) in the stroma.
光合作用发生在叶绿体中，将光能转化为储存在葡萄糖中的化学能。它包括两个阶段：类囊体膜上的光依赖反应和基质中的光不依赖反应（卡尔文循环）。
In the light-dependent reaction, light energy splits water (photolysis) to produce electrons, protons, and O₂. Excited electrons pass along an electron transport chain, generating ATP via chemiosmosis and reducing NADP⁺ to NADPH.
在光依赖反应中，光能分解水（光解），产生电子、质子和氧气。激发态电子沿电子传递链传递，通过化学渗透生成 ATP，并将 NADP⁺ 还原为 NADPH。
The Calvin cycle uses ATP and NADPH to fix CO₂. Ribulose bisphosphate (RuBP) combines with CO₂ to form two molecules of glycerate 3-phosphate (GP), which are reduced to triose phosphate (TP) and eventually regenerated to RuBP.
卡尔文循环利用 ATP 和 NADPH 固定二氧化碳。核酮糖二磷酸 (RuBP) 与 CO₂ 结合形成两分子甘油酸-3-磷酸 (GP)，GP 被还原为磷酸丙糖 (TP)，最终再生成 RuBP。
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
2. Respiration | 呼吸作用
Respiration releases energy from organic molecules to produce ATP. Aerobic respiration involves four stages: glycolysis, the link reaction, the Krebs cycle, and oxidative phosphorylation.
呼吸作用从有机分子中释放能量合成 ATP。有氧呼吸包括四个阶段：糖酵解、链接反应、克雷布斯循环和氧化磷酸化。
Glycolysis in the cytoplasm splits glucose (6C) into two pyruvate (3C), producing a net gain of 2 ATP and 2 reduced NAD (NADH).
糖酵解在细胞质中将葡萄糖 (6C) 分解为两分子丙酮酸 (3C)，净产生 2 个 ATP 和 2 个还原型 NAD (NADH)。
In the link reaction, pyruvate enters the mitochondrial matrix, loses CO₂, and is oxidised to acetyl coenzyme A, producing one NADH per pyruvate.
在链接反应中，丙酮酸进入线粒体基质，脱去 CO₂，被氧化为乙酰辅酶 A，每分子丙酮酸产生一分子 NADH。
The Krebs cycle completes the oxidation of acetyl-CoA. Each turn yields 3 NADH, 1 FADH₂, 1 ATP (via substrate-level phosphorylation), and 2 CO₂.
克雷布斯循环完成乙酰辅酶 A 的彻底氧化。每一轮产生 3 个 NADH、1 个 FADH₂、1 个 ATP（底物水平磷酸化）和 2 个 CO₂。
Oxidative phosphorylation on the inner mitochondrial membrane passes electrons from NADH and FADH₂ along carriers, pumping protons to create a gradient. ATP synthase harnesses the proton flow to synthesise many ATP; oxygen acts as the final electron acceptor, forming water.
氧化磷酸化在线粒体内膜上进行，NADH 和 FADH₂ 的电子沿传递链传递，泵出质子形成梯度。ATP 合酶利用质子回流合成大量 ATP；氧气作为最终电子受体生成水。
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy (ATP)
3. Energy and Ecosystems | 能量与生态系统
In ecosystems, energy enters through producers (plants) during photosynthesis. The total chemical energy fixed is gross primary production (GPP). Net primary production (NPP) is GPP minus respiratory losses (R): NPP = GPP − R. NPP represents energy available for growth and consumers.
在生态系统中，能量通过生产者（植物）的光合作用输入。固定的总化学能称为总初级生产力 (GPP)。净初级生产力 (NPP) 等于 GPP 减去呼吸损耗 (R)：NPP = GPP − R。NPP 代表可供生长和消费者利用的能量。
Energy is transferred along food chains, but much is lost in feces, urine, and as heat from respiration. Only about 10% of energy is passed to the next trophic level. Biomass pyramids reflect this energy attenuation.
能量沿食物链传递，但大部分随粪便、尿液和呼吸热散失。只有约 10% 的能量进入下一营养级。生物量金字塔反映了这种能量衰减。
4. Nutrient Cycles | 营养循环
Nutrients such as carbon and nitrogen are recycled in ecosystems. In the carbon cycle, CO₂ is fixed by photosynthesis and returned by respiration, decomposition, and combustion. Oceans and fossil fuels act as long-term carbon stores.
碳、氮等营养物质在生态系统中循环利用。碳循环中，CO₂ 通过光合作用固定，通过呼吸、分解和燃烧返回大气。海洋和化石燃料是长期碳库。
The nitrogen cycle involves four main microbial processes: nitrogen fixation (e.g., by Rhizobium in root nodules), ammonification, nitrification (by Nitrosomonas and Nitrobacter), and denitrification. Saprobionts digest organic matter, releasing ammonium ions.
氮循环涉及四大微生物过程：固氮（如根瘤中的根瘤菌）、氨化、硝化（亚硝化单胞菌和硝化杆菌）和反硝化。腐生菌分解有机物释放铵离子。
Mycorrhizae are mutualistic associations between fungi and plant roots that enhance water and phosphate uptake, crucial in nutrient-poor soils. Eutrophication can result from excess nitrate and phosphate runoff, causing algal blooms and oxygen depletion.
菌根是真菌与植物根系的互利共生体，能增强水分和磷酸盐吸收，在贫瘠土壤中尤为重要。过量硝酸盐和磷酸盐径流可导致富营养化，引发藻华及缺氧死区。
5. Nervous Coordination | 神经系统协调
Neurones transmit electrical impulses. The resting potential (−70 mV) is maintained by the sodium–potassium pump (3 Na⁺ out, 2 K⁺ in) and differential membrane permeability.
神经元传递电冲动。静息电位 (−70 mV) 由钠钾泵（泵出 3 Na⁺，泵入 2 K⁺）和膜对离子的差异通透性维持。
An action potential is generated when depolarisation reaches the threshold, opening voltage-gated Na⁺ channels. Na⁺ influx raises the potential to about +40 mV, after which Na⁺ channels close and voltage-gated K⁺ channels open, causing repolarisation. The brief hyperpolarisation is corrected by the pump. The impulse is all-or-nothing and propagates by saltatory conduction in myelinated axons.
当去极化达到阈值时产生动作电位，电压门控 Na⁺ 通道开放。Na⁺ 内流使膜电位升到约 +40 mV，随后 Na⁺ 通道关闭、电压门控 K⁺ 通道开放，引起复极化。短暂的超极化由泵恢复。冲动全或无，在有髓轴突中以跳跃传导方式传播。
At a synapse, the arriving impulse triggers Ca²⁺ entry, causing vesicles to release neurotransmitter into the synaptic cleft. The neurotransmitter binds to receptors on the postsynaptic membrane, generating an excitatory or inhibitory postsynaptic potential. Summation of signals determines whether a new action potential fires.
在突触处，到来的冲动引发 Ca²⁺ 内流，促使囊泡向突触间隙释放神经递质。递质与突触后膜受体结合，产生兴奋性或抑制性突触后电位。信号的累加决定是否会引发新的动作电位。
6. Muscle Contraction | 肌肉收缩
Skeletal muscle fibres contain many myofibrils made of repeating sarcomeres. The sarcomere includes thin actin filaments and thick myosin filaments, arranged in a banded structure (I-band, A-band, H-zone).
骨骼肌纤维含有大量由肌节重复构成的肌原纤维。肌节包含细的肌动蛋白丝和粗的肌球蛋白丝，排列形成横纹结构（I 带、A 带、H 区）。
The sliding filament model: calcium ions released from the sarcoplasmic reticulum bind to troponin, causing tropomyosin to expose myosin-binding sites on actin. Myosin heads bind, perform a power stroke using energy from ATP hydrolysis, and pull the actin filament toward the centre. ATP also detaches the myosin head. Repeated cycles shorten the sarcomere.
滑动丝模型：肌浆网释放的钙离子与肌钙蛋白结合，使原肌球蛋白移位暴露肌动蛋白上的结合位点。肌球蛋白头与之结合，利用 ATP 水解能量完成动力冲程，将肌动蛋白丝拉向中央。ATP 也使肌球蛋白头解离。循环往复导致肌节缩短。
The neuromuscular junction functions like a synapse: an action potential opens Ca²⁺ channels, triggering acetylcholine release, which depolarises the muscle fibre membrane and initiates contraction.
神经肌肉接头功能类似突触：动作电位使 Ca²⁺ 通道开放，触发乙酰胆碱释放，导致肌纤维膜去极化并启动收缩。
7. Homeostasis | 体内平衡
Homeostasis maintains a stable internal environment via negative feedback loops involving receptors, control centres, and effectors.
体内平衡通过由感受器、控制中心和效应器组成的负反馈回路维持内环境稳定。
Blood glucose regulation: when blood glucose rises, pancreatic β cells secrete insulin, which promotes glucose uptake and glycogenesis in the liver. When glucose falls, α cells secrete glucagon, stimulating glycogenolysis and gluconeogenesis. Adrenaline also raises blood glucose in stress.
血糖调节：血糖升高时，胰岛 β 细胞分泌胰岛素，促进肝脏摄取葡萄糖和糖原合成。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。肾上腺素在应激时也提升血糖。
Thermoregulation involves the hypothalamus. In cold, shivering, vasoconstriction, and increased metabolism generate heat; in heat, sweating and vasodilation dissipate heat.
体温调节由下丘脑协调。寒冷时，颤抖、血管收缩和代谢增强产生热量；高温时，出汗和血管舒张散热。
Osmoregulation: osmoreceptors in the hypothalamus detect low water potential, triggering ADH release from the posterior pituitary. ADH increases water permeability of collecting duct cells, reducing urine volume.
渗透压调节：下丘脑的渗透压感受器探测到水势降低，促使垂体后叶释放 ADH。ADH 增加集合管细胞对水的通透性，减少尿量。
8. Inheritance and Evolution | 遗传与进化
The Hardy–Weinberg principle predicts that allele frequencies in a large, randomly mating population remain constant if no mutation, migration, or natural selection occurs. It provides a null hypothesis for studying evolutionary change.
哈迪-温伯格原理预测，在没有突变、迁移、自然选择且随机交配的大种群中，等位基因频率可维持恒定。它为分析进化变化提供了零假设。
p + q = 1 p² + 2pq + q² = 1
Here, p and q represent the frequencies of the dominant and recessive alleles. The terms p², 2pq, and q² give the expected genotype frequencies. Using these equations, you can calculate carrier frequencies and predict changes over generations.
式中 p 和 q 代表显性和隐性等位基因的频率。p²、2pq 和 q² 为预期的基因型频率。利用这些方程可计算携带者频率，并预测世代间的变化。
Natural selection acts on phenotypes determined by alleles. Stabilising selection favours the mean, directional selection favours one extreme, and disruptive selection favours both extremes. This leads to adaptation and, eventually, speciation when reproductive isolation occurs.
自然选择作用于由等位基因决定的表型。稳定选择偏好中间类型，定向选择偏好某一极端，分裂选择偏好两个极端。这导致适应，并在产生生殖隔离时最终引发物种形成。
9. Control of Gene Expression | 基因表达调控
Transcription factors are proteins that bind to specific DNA sequences (promoters, enhancers) to regulate RNA polymerase activity, thereby switching genes on or off. Oestrogen, for example, binds to an intracellular receptor, which then acts as a transcription factor to promote gene expression.
转录因子是能与特定 DNA 序列（启动子、增强子）结合以调控 RNA 聚合酶活性的蛋白质，从而开启或关闭基因。例如，雌激素与胞内受体结合，后者充当转录因子促进基因表达。
Epigenetic modifications alter gene expression without changing the DNA sequence. DNA methylation adds methyl groups to cytosine, usually repressing transcription. Histone modification (acetylation) relaxes chromatin, promoting transcription.
表观遗传修饰在不改变 DNA 序列的情况下调控基因表达。DNA 甲基化在胞嘧啶上添加甲基，通常抑制转录。组蛋白修饰（乙酰化）可使染色质松弛，促进转录。
RNA interference (RNAi) involves small interfering RNA (siRNA) or microRNA (miRNA). After processing by Dicer, one strand of siRNA associates with the RISC complex. The complex binds to complementary mRNA, causing its degradation or blocking translation. This post-transcriptional control is important in development and defence against viruses.
RNA 干扰 (RNAi) 涉及小干扰 RNA (siRNA) 或微 RNA (miRNA)。经 Dicer 酶加工后，siRNA 的一条链与 RISC 复合体结合。该复合体与互补的 mRNA 结合，导致其降解或阻断翻译。这种转录后调控在发育和抗病毒防御中至关重要。
10. Recombinant DNA Technology | 重组 DNA 技术
Recombinant DNA technology allows the transfer of genes between organisms. A target gene is isolated and cut with restriction endonucleases, producing sticky ends. The same enzyme is used to cut a vector, such as a plasmid. DNA ligase joins the gene into the vector, which is then introduced into host cells by heat shock or electroporation.
重组 DNA 技术可实现生物体间的基因转移。目标基因被分离并用限制性内切酶切割，产生粘性末端。相同的酶切割载体（如质粒）。DNA 连接酶将基因连接到载体中，随后通过热激或电穿孔引入宿主细胞。
Selectable markers (antibiotic resistance genes, fluorescent proteins) help identify transformed cells. The host cells multiply, cloning the gene or expressing the protein product. This process is used to produce human insulin and other pharmaceuticals.
选择标记（抗生素抗性基因、荧光蛋白）帮助识别转化细胞。宿主细胞增殖，实现对基因的克隆或蛋白产物的表达。此技术用于生产人胰岛素等药物。
The polymerase chain reaction (PCR) amplifies DNA in vitro. Three steps in a thermocycler: denaturation (95 °C) separates strands; annealing (∼55–65 °C) allows primers to bind; extension (72 °C) with Taq polymerase synthesises new strands. After many cycles, millions of copies are generated.
聚合酶链式反应 (PCR) 在体外扩增 DNA。热循环仪中三步：变性 (95 °C) 解开双链；退火 (∼55–65 °C) 让引物结合；延伸 (72 °C) 由 Taq 聚合酶合成新链。多次循环后获得数百万拷贝。
Gel electrophoresis separates DNA fragments by size. DNA is loaded into wells and subjected to an electric field; smaller fragments migrate farther. Southern blotting and DNA probes with radioactive or fluorescent labels enable the identification of specific sequences.
凝胶电泳按大小分离 DNA 片段。DNA 加样后施加电场，较小的片段迁移更快。Southern 印迹法及放射性或荧光标记的 DNA 探针可鉴定特定序列。
Published by TutorHao | Biology Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
屏轩国际教育cambridge primary/secondary checkpoint, cat4, ukiset,ukcat,igcse,alevel,PAT,STEP,MAT, ibdp,ap,ssat,sat,sat2课程辅导，国外大学本科硕士研究生博士课程论文辅导