AS Eduqas Biology: Core Concepts Revision | AS Eduqas 生物：核心知识点梳理

📚 AS Eduqas Biology: Core Concepts Revision | AS Eduqas 生物：核心知识点梳理

Welcome to this comprehensive rundown of the essential AS Eduqas Biology syllabus. Covering both Unit 1 (Basic Biochemistry and Cell Organisation) and Unit 2 (Biodiversity and Physiology), this guide connects the dots between molecular structures, cellular processes, organismal systems and the diversity of life. Each section is presented in clear bilingual pairs to help you master the key terms and mechanisms confidently.

欢迎来到AS Eduqas生物核心知识点梳理。本文覆盖单元一（基础生物化学与细胞组织）和单元二（生物多样性与生理学），将分子结构、细胞过程、机体系统与生命多样性串联起来。每个部分都以清晰的中英双语对照呈现，帮助你扎实掌握关键术语和机制。

1. Biological Molecules: Carbohydrates, Lipids and Proteins | 生物分子：碳水化合物、脂质与蛋白质

All living organisms are built from carbon-based macromolecules. Monomers such as monosaccharides, amino acids and fatty acids join by condensation reactions that release water. The reverse process, hydrolysis, uses water to break polymers back into monomers.

所有生命体都由碳基大分子构成。单糖、氨基酸和脂肪酸等单体通过缩合反应连接，释放水分子。逆过程水解则利用水将聚合物分解回单体。

Carbohydrates contain carbon, hydrogen and oxygen in a 1:2:1 ratio. Glucose (C₆H₁₂O₆) exists as α- and β-isomers. Disaccharides like maltose and sucrose form through glycosidic bonds. Polysaccharides serve distinct roles: starch (amylose and amylopectin) and glycogen store energy, while cellulose provides structural strength in plant cell walls due to its β-1,4 linkages.

碳水化合物含有碳、氢、氧，比例为1:2:1。葡萄糖(C₆H₁₂O₆)存在α和β异构体。麦芽糖和蔗糖等双糖通过糖苷键形成。多糖各有分工：淀粉（直链淀粉和支链淀粉）和糖原储存能量，而纤维素凭借β-1,4糖苷键为植物细胞壁提供结构强度。

Lipids are non-polar and insoluble in water. Triglycerides consist of one glycerol molecule esterified to three fatty acid chains; they store energy efficiently due to their high proportion of saturated hydrocarbons. Phospholipids replace one fatty acid with a phosphate group, creating an amphipathic molecule essential for membrane formation.

脂质是非极性、不溶于水的分子。甘油三酯由一个甘油分子与三条脂肪酸链酯化形成；因其饱和烃比例高，能高效储存能量。磷脂则用一个磷酸基替换一条脂肪酸，形成兼性分子，对膜的构建至关重要。

Proteins are polymers of amino acids linked by peptide bonds. The primary structure is the linear sequence; secondary structures include α-helices and β-pleated sheets; tertiary structure arises from folding due to hydrogen bonds, ionic bonds, disulphide bridges and hydrophobic interactions; quaternary structure involves multiple polypeptides, as seen in haemoglobin.

蛋白质是氨基酸通过肽键连接而成的聚合物。一级结构为线性序列；二级结构包括α-螺旋和β-折叠；三级结构由氢键、离子键、二硫桥和疏水相互作用引起的折叠形成；四级结构涉及多条多肽链，如血红蛋白。

2. Water and Inorganic Ions | 水与无机离子

Water is a polar solvent, meaning it can dissolve charged and polar substances, facilitating metabolic reactions and transport. Its high specific heat capacity buffers temperature changes, while its large latent heat of vaporisation enables effective cooling through sweating or transpiration. Ice floats because water molecules in ice form a lattice that is less dense than liquid water, insulating aquatic life.

水是一种极性溶剂，能溶解带电和极性物质，从而促进代谢反应和运输。其高比热容可缓冲温度变化，而高汽化潜热使得通过出汗或蒸腾作用有效散热。冰漂浮是因为水分子在冰中形成的晶格密度低于液态水，为水生生物提供了保温层。

Inorganic ions are essential for a range of physiological processes. Sodium ions (Na⁺) contribute to generating nerve impulses; potassium ions (K⁺) maintain the resting potential and regulate stomatal opening; calcium ions (Ca²⁺) are crucial for muscle contraction and exocytosis; phosphate ions (PO₄³⁻) form part of nucleotides and ATP; iron ions (Fe²⁺) are central in the haem group of haemoglobin for oxygen binding.

无机离子对许多生理过程至关重要。钠离子(Na⁺)参与产生神经冲动；钾离子(K⁺)维持静息电位并调节气孔开闭；钙离子(Ca²⁺)对肌肉收缩和胞吐作用至关重要；磷酸根离子(PO₄³⁻)是核苷酸和ATP的组成部分；铁离子(Fe²⁺)是血红蛋白血红素基团的核心，用于结合氧气。

3. Cell Structure: Eukaryotes and Prokaryotes | 细胞结构：真核生物与原核生物

Eukaryotic cells possess a true nucleus enclosed by a double membrane and contain membrane-bound organelles. Key organelles include mitochondria for aerobic respiration, chloroplasts for photosynthesis, ribosomes for protein synthesis, rough and smooth endoplasmic reticulum, the Golgi apparatus for modification and packaging, and lysosomes for digestion. Plant cells have a permanent vacuole and a cellulose cell wall.

真核细胞具有被双层膜包裹的真正的细胞核，并含有膜结合细胞器。关键的细胞器包括用于有氧呼吸的线粒体、用于光合作用的叶绿体、合成蛋白质的核糖体、糙面和滑面内质网、用于修饰和包装的高尔基体，以及用于消化的溶酶体。植物细胞还具有永久液泡和纤维素细胞壁。

Prokaryotic cells, such as bacteria, lack a nucleus and membrane-bound organelles. Their circular DNA is free in the cytoplasm, and they may have plasmids. Ribosomes are 70S, smaller than the 80S ribosomes in eukaryotes. Some have a protective capsule, flagella for movement, and pili for attachment or conjugation. Viruses are non-living and consist of nucleic acid surrounded by a protein capsid, sometimes with an envelope derived from the host cell membrane.

原核细胞，如细菌，没有细胞核和膜结合细胞器。其环状DNA游离在细胞质中，可能含有质粒。核糖体为70S，比真核生物的80S核糖体小。有些具有保护性荚膜、用于运动的鞭毛以及用于附着或接合的菌毛。病毒是非生命体，由核酸和蛋白质衣壳组成，有时带有源自宿主细胞膜的包膜。

4. Cell Membranes and Transport Mechanisms | 细胞膜与运输机制

The fluid mosaic model describes the cell membrane as a phospholipid bilayer with embedded proteins. Phospholipids have hydrophilic phosphate heads and hydrophobic fatty acid tails, creating a selectively permeable barrier. Cholesterol modulates fluidity. Intrinsic proteins span the bilayer and can function as channels or carriers; extrinsic proteins lie on the surface and act as receptors or enzymes. Glycoproteins and glycolipids form the glycocalyx for cell recognition.

流动镶嵌模型将细胞膜描述为嵌有蛋白质的磷脂双分子层。磷脂具有亲水的磷酸头部和疏水的脂肪酸尾部，形成选择透过性屏障。胆固醇调节流动性。内在蛋白贯穿双分子层，可作为通道或载体；外在蛋白位于表面，充当受体或酶。糖蛋白和糖脂构成糖萼，参与细胞识别。

Passive transport includes diffusion (movement of small, non-polar molecules down a concentration gradient) and facilitated diffusion using channel or carrier proteins. Osmosis is the diffusion of water through a selectively permeable membrane from an area of higher water potential to lower water potential. Active transport requires ATP and carrier proteins to move substances against the concentration gradient; examples include the sodium-potassium pump. Bulk transport via endocytosis and exocytosis moves large molecules across the membrane.

被动运输包括扩散（小分子非极性物质顺浓度梯度移动）和利用通道蛋白或载体蛋白的协助扩散。渗透是水通过选择透过性膜从水势高的区域向水势低的区域扩散。主动运输需要ATP和载体蛋白，逆浓度梯度移动物质；例如钠钾泵。通过胞吞和胞吐进行的批量运输则移动大分子进出细胞。

5. Enzymes: Structure, Function and Factors | 酶：结构、功能与影响因素

Enzymes are globular proteins that act as biological catalysts, lowering activation energy without being consumed. The specific region where substrates bind is the active site, complementary in shape to the substrate. The lock-and-key model proposes a perfect fit, while the induced-fit model suggests the active site changes shape to mould around the substrate, forming enzyme-substrate complexes.

酶是球状蛋白质，充当生物催化剂，降低活化能而自身不被消耗。底物结合的特定区域是活性位点，其形状与底物互补。锁钥模型提出完美匹配，而诱导契合模型认为活性位点改变形状以包裹底物，形成酶-底物复合物。

Enzyme activity is affected by temperature and pH. As temperature rises, kinetic energy increases, leading to more frequent collisions; activity peaks at an optimum temperature. Beyond this, hydrogen bonds break, denaturing the enzyme and changing the active site irreversibly. Similarly, extreme pH disrupts ionic and hydrogen bonds, altering the active site’s charge and shape. Enzyme concentration and substrate concentration also limit the rate of reaction, until saturation is reached.

酶活性受温度和pH影响。温度升高时动能增加，碰撞更频繁，活性在最适温度达到峰值。超过该温度，氢键断裂，酶变性，活性位点不可逆改变。同样，极端pH破坏离子键和氢键，改变活性位点的电荷和形状。酶浓度和底物浓度也会限制反应速率，直到达到饱和。

Competitive inhibitors have a shape similar to the substrate and bind to the active site, reducing activity; this effect can be overcome by increasing substrate concentration. Non-competitive inhibitors bind to an allosteric site, changing the active site’s shape, and cannot be overcome by adding more substrate. End-product inhibition is a form of negative feedback where the final product inhibits an early enzyme in the pathway.

竞争性抑制剂形状与底物相似，结合活性位点降低活性；增加底物浓度可克服该效应。非竞争性抑制剂结合别构位点，改变活性位点形状，无法通过增加底物来克服。终产物抑制是一种负反馈，最终产物抑制代谢途径中早期的酶。

6. Nucleic Acids: DNA and RNA Structure | 核酸：DNA与RNA的结构

Nucleic acids are polymers of nucleotides. Each nucleotide consists of a pentose sugar, a phosphate group and a nitrogenous base. DNA uses deoxyribose, while RNA uses ribose. The bases are adenine (A), thymine (T), cytosine (C) and guanine (G) in DNA; RNA has uracil (U) instead of thymine. Nucleotides pair through complementary base pairing: A–T (or A–U) and C–G via hydrogen bonds.

核酸是核苷酸的聚合物。每个核苷酸由戊糖、磷酸基团和含氮碱基组成。DNA使用脱氧核糖，RNA使用核糖。DNA中的碱基为腺嘌呤(A)、胸腺嘧啶(T)、胞嘧啶(C)和鸟嘌呤(G)；RNA中用尿嘧啶(U)代替胸腺嘧啶。核苷酸通过互补碱基配对：A–T（或A–U）和C–G通过氢键连接。

DNA forms a double helix: two antiparallel strands (5′ to 3′ and 3′ to 5′) held together by hydrogen bonds between base pairs. The sugar–phosphate backbone provides structural stability. RNA is typically single-stranded and comes in three main forms: messenger RNA (mRNA), transfer RNA (tRNA) and ribosomal RNA (rRNA), each playing a distinct role in protein synthesis.

DNA形成双螺旋结构：两条反平行的链（5’到3’和3’到5’）通过碱基对之间的氢键连接。糖-磷酸骨架提供结构稳定性。RNA通常为单链，主要有三种形式：信使RNA（mRNA）、转运RNA（tRNA）和核糖体RNA（rRNA），各自在蛋白质合成中扮演不同的角色。

7. DNA Replication and Protein Synthesis | DNA的复制与蛋白质的合成

DNA replication occurs during the S phase of interphase and is semiconservative; each new DNA molecule contains one original strand and one newly synthesised strand. The enzyme DNA helicase unwinds the double helix and breaks hydrogen bonds. RNA primase adds short RNA primers, allowing DNA polymerase to add complementary nucleotides in the 5′ to 3′ direction. The leading strand is synthesised continuously, while the lagging strand forms Okazaki fragments joined by DNA ligase.

DNA复制发生在间期的S期，是半保留复制；每个新DNA分子含有一条原始链和一条新合成的链。DNA解旋酶解开双螺旋并断裂氢键。RNA引物酶添加短RNA引物，使DNA聚合酶能够沿5’到3’方向添加互补核苷酸。前导链连续合成，后随链形成冈崎片段，由DNA连接酶连接。

Protein synthesis involves transcription and translation. In the nucleus, RNA polymerase binds to the promoter, unwinds a section of DNA and synthesises a complementary mRNA strand using the template strand. The mRNA is processed (splicing) by removing introns and joining exons. It then exits the nucleus. At the ribosome, translation begins when mRNA codons are read. tRNA molecules with complementary anticodons deliver specific amino acids; peptide bonds form between amino acids, creating a polypeptide chain until a stop codon is reached.

蛋白质合成包括转录和翻译。在细胞核内，RNA聚合酶结合启动子，解开一段DNA，以模板链为模板合成互补的mRNA链。mRNA经过加工（剪接）去除内含子、连接外显子，然后离开细胞核。在核糖体上，翻译从读取mRNA密码子开始。携带互补反密码子的tRNA分子运送特定氨基酸；氨基酸之间形成肽键，合成多肽链，直到遇到终止密码子。

8. Cell Cycle and Mitosis | 细胞周期与有丝分裂

The cell cycle consists of interphase (G₁, S, G₂) and mitotic phase (mitosis and cytokinesis). During interphase, the cell grows, replicates its DNA and synthesises proteins. Mitosis produces two genetically identical daughter cells for growth, repair and, in some organisms, asexual reproduction.

细胞周期包括间期（G₁期、S期、G₂期）和分裂期（有丝分裂和胞质分裂）。在间期，细胞生长、复制DNA并合成蛋白质。有丝分裂产生两个遗传上相同的子细胞，用于生长、修复以及某些生物的无性繁殖。

The stages of mitosis are prophase, metaphase, anaphase and telophase. In prophase, chromosomes condense and spindle fibres form. During metaphase, chromosomes align at the equator. Anaphase sees sister chromatids separate and move to opposite poles. Telophase involves the formation of two new nuclear envelopes. Cytokinesis then divides the cytoplasm; in animal cells, a cleavage furrow forms, while in plant cells, a cell plate develops.

有丝分裂的阶段包括前期、中期、后期和末期。前期染色体凝集，纺锤体形成。中期染色体排列在赤道面。后期姐妹染色单体分离并移向两极。末期形成两个新的核膜。随后胞质分裂分割细胞质；动物细胞形成分裂沟，植物细胞则形成细胞板。

9. Biodiversity: Species, Phylogeny and Classification | 生物多样性：物种、系统发育与分类

A species is defined as a group of organisms that can interbreed to produce fertile offspring. Biodiversity encompasses the variety of species, genetic diversity within species and ecosystem diversity. Classification systems put organisms into a hierarchy: domain, kingdom, phylum, class, order, family, genus, species. The three-domain system (Archaea, Bacteria, Eukarya) is based on rRNA analysis.

物种被定义为能够相互交配并产生可育后代的一群生物。生物多样性包含物种多样性、物种内的遗传多样性和生态系统多样性。分类系统将生物纳入层级：域、界、门、纲、目、科、属、种。三域系统（古菌域、细菌域、真核域）基于rRNA分析。

Phylogenetic trees illustrate evolutionary relationships based on shared derived characteristics and genetic evidence. The five-kingdom system (Prokaryotae, Protoctista, Fungi, Plantae, Animalia) remains useful for understanding broad differences. When classifying, organisms are placed into groups using observable characteristics and molecular data, aiming to reflect common ancestry rather than just appearance.

系统发育树根据共享衍征和遗传证据展示进化关系。五界系统（原核生物界、原生生物界、真菌界、植物界、动物界）有助于理解大致的差异。分类时，利用可观察特征和分子数据将生物归入不同类群，力求反映共同祖先而非仅仅是外表相似。

Sampling techniques allow estimation of biodiversity. Random sampling with quadrats, line transects and mark-release-recapture methods help calculate species richness and evenness. Simpson’s index of diversity (D) can be used to quantify biodiversity in a habitat.

取样技术可用来估算生物多样性。随机样方取样、样线法和标记重捕法有助于计算物种丰富度和均匀度。辛普森多样性指数可用于量化栖息地的生物多样性。

10. Gas Exchange Systems | 气体交换系统

Gas exchange supplies oxygen for respiration and removes carbon dioxide. In humans, air enters through the nasal cavity, passes the pharynx, larynx, trachea, bronchi and bronchioles, reaching the alveoli. Alveoli are surrounded by capillaries; oxygen diffuses into the blood while carbon dioxide diffuses out. The alveolar wall is thin, moist and well ventilated, featuring a large surface area to maximise diffusion rates.

气体交换为呼吸提供氧气并排出二氧化碳。在人体中，空气经鼻腔进入，通过咽、喉、气管、支气管和细支气管，到达肺泡。肺泡被毛细血管包围；氧气扩散进入血液，二氧化碳扩散排出。肺泡壁薄而湿润，通风良好，表面积大，以最大限度地提高扩散速率。

In fish, countercurrent flow in the gill lamellae maintains a concentration gradient along the entire gas exchange surface, enabling efficient extraction of oxygen from water. Insects use a tracheal system where air enters through spiracles and travels down tracheae and tracheoles directly to tissues; rhythmic ventilation and fluid at the tracheole tips help manage gas exchange during high activity.

在鱼类中，鳃瓣中的逆流交换沿整个气体交换表面维持浓度梯度，从而高效地从水中摄取氧气。昆虫使用气管系统，空气通过气门进入，经由气管和微气管直接输送到组织；节律性通风和微气管末端的液体有助于在高活动期间管理气体交换。

Plants exchange gases through stomata, mainly on the lower leaf surface. Guard cells control stomatal opening by changing turgor pressure in response to light and CO₂ concentrations. Lenticels in stems and pneumatophores in mangrove roots also facilitate gas exchange in specific environments.

植物通过气孔（主要位于叶下表面）进行气体交换。保卫细胞根据光照和CO₂浓度改变膨压，控制气孔开闭。茎上的皮孔和红树林根部的呼吸根也在特定环境中促进气体交换。

11. Transport Systems and Immune Defence | 运输系统与免疫防御

Multicellular organisms require transport systems to deliver nutrients and remove waste. In mammals, the circulatory system is a closed, double system. The heart pumps deoxygenated blood to the lungs (pulmonary circulation) and oxygenated blood to the body (systemic circulation). Blood passes through arteries, arterioles, capillaries, venules and veins. The cardiac cycle involves atrial and ventricular systole and diastole, controlled by the sinoatrial node and Purkinje fibres.

多细胞生物需要运输系统输送营养物质并清除废物。哺乳动物的循环系统是封闭的双循环系统。心脏将缺氧血泵送到肺部（肺循环），将富氧血泵送到全身（体循环）。血液流经动脉、小动脉、毛细血管、小静脉和静脉。心动周期包括心房和心室的收缩与舒张，由窦房结和浦肯野纤维控制。

Blood consists of plasma, erythrocytes (red blood cells), leucocytes (white blood cells) and platelets. Erythrocytes lack a nucleus and are packed with haemoglobin for oxygen transport. Leucocytes include phagocytes (neutrophils, macrophages) and lymphocytes (B cells, T cells), central to immune defence.

血液由血浆、红细胞、白细胞和血小板组成。红细胞无细胞核，充满血红蛋白用于运输氧气。白细胞包括吞噬细胞（中性粒细胞、巨噬细胞）和淋巴细胞（B细胞、T细胞），在免疫防御中起核心作用。

In plants, xylem transports water and mineral ions upwards via transpiration pull, cohesion and adhesion. Phloem transports organic solutes from sources to sinks by mass flow. Sieve tube elements and companion cells cooperate to achieve translocation. Root pressure and capillarity contribute only minimally to upward movement.

在植物中，木质部通过蒸腾拉力、内聚力和附着力向上运输水分和矿质离子。韧皮部通过集流将有机溶质从源输送到库。筛管分子和伴胞协同完成转运。根压和毛细作用对向上运动的贡献很小。

The immune system provides non-specific and specific defences. Physical barriers include skin and mucous membranes. Phagocytosis by phagocytes engulfs pathogens. Lymphocytes mount specific responses: B cells produce antibodies (humoral immunity), while T cells destroy infected cells or coordinate other immune cells (cell-mediated immunity). Memory cells remain after infection, granting faster, stronger secondary responses.

免疫系统提供非特异性和特异性防御。物理屏障包括皮肤和粘膜。吞噬细胞通过吞噬作用吞没病原体。淋巴细胞发起特异性应答：B细胞产生抗体（体液免疫），T细胞摧毁受感染细胞或协调其他免疫细胞（细胞介导免疫）。感染后记忆细胞存留，确保更快、更强的二次应答。

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AS Eduqas Biology: Core Concepts Revision | AS Eduqas 生物：核心知识点梳理