📚 Mind Map Quick Revision for IGCSE OCR Biology | IGCSE OCR 生物：思维导图速记
This article turns the entire IGCSE OCR Biology syllabus into a set of visual mind map nodes. Each key topic is broken down into central concepts and radiating branches, helping you see connections and recall details quickly. Read the English, then the Chinese for every point to lock in understanding.
本文把 IGCSE OCR 生物全部考点拆解成一组可视化的思维导图节点。每个核心主题都划分为中心概念和向外发散的枝条，让你一眼看清联系并快速回忆。每一条都先读英文、再读中文，把理解记牢。
1. MRS GREN: The Seven Life Processes | MRS GREN：七大生命过程
Mind map node: Life Processes → MRS GREN
思维导图节点：生命过程 → MRS GREN
Movement: an action by an organism causing a change of position or place.
运动：生物体引起位置或场所改变的动作。
Respiration: the chemical reactions in cells that break down nutrient molecules to release energy for metabolism.
呼吸：细胞内分解营养物质以释放代谢所需能量的化学反应。
Sensitivity: the ability to detect or sense changes in the internal or external environment and to make appropriate responses.
感知：探测或感应内、外环境变化并作出适宜反应的能力。
Growth: a permanent increase in size and dry mass by an increase in cell number or cell size.
生长：通过细胞数目增多或细胞体积增大而使体积和干重永久性增加。
Reproduction: the processes that make more of the same kind of organism.
生殖：产生更多同类生物体的过程。
Excretion: removal from organisms of the waste products of metabolism, toxic materials, and substances in excess of requirements.
排泄：把代谢废物、有毒物质以及超过需要的多余物质从生物体内排出。
Nutrition: taking in of materials for energy, growth and development; plants require light, carbon dioxide, water and mineral ions; animals require organic food.
营养：摄取用于能量、生长和发育的物质；植物需要光、二氧化碳、水和矿质离子；动物需要有机食物。
Use the mnemonic MRS GREN to remember these seven characteristics. Every living organism carries out all of them.
用助记符 MRS GREN 记住这七大特征。每个活的生物体都要完成全部七项。
2. Cell Structure and Organisation | 细胞结构与组织层次
: Cell → Common features (animal and plant) → Plant-only features → Levels of organisation
思维导图节点：细胞 → 共同结构（动植物）→ 植物特有结构 → 组织层次
All cells have a cell membrane, cytoplasm, and genetic material in the form of DNA. Plant cells also have a cellulose cell wall, a large permanent vacuole and chloroplasts.
所有细胞都有细胞膜、细胞质和以 DNA 形式存在的遗传物质。植物细胞还有纤维素细胞壁、一个中央大液泡和叶绿体。
| Structure (English) | 功能 (中文) |
|---|---|
| Cell membrane – controls movement of substances in and out | 细胞膜 – 控制物质进出 |
| Cytoplasm – site of metabolic reactions | 细胞质 – 代谢反应场所 |
| Nucleus – contains DNA, controls cell activities | 细胞核 – 含 DNA，控制细胞活动 |
| Mitochondria – aerobic respiration, release energy | 线粒体 – 有氧呼吸，释放能量 |
| Ribosomes – protein synthesis | 核糖体 – 蛋白质合成 |
| Cell wall (plants) – cellulose, provides support | 细胞壁（植物） – 纤维素，提供支撑 |
| Chloroplasts (plants) – photosynthesis, contain chlorophyll | 叶绿体（植物） – 光合作用，含叶绿素 |
| Permanent vacuole (plants) – contains cell sap, maintains turgor | 中央液泡（植物） – 含细胞液，维持膨压 |
Levels of organisation: Cells form tissues; tissues form organs; organs form organ systems; organ systems make up the whole organism.
组织层次：细胞构成组织；组织构成器官；器官构成器官系统；器官系统构成完整生物体。
3. Biological Molecules | 生物分子
Mind map node: Biological molecules → Carbohydrates, Lipids, Proteins, DNA → Food tests
思维导图节点：生物分子 → 碳水化合物、脂质、蛋白质、DNA → 食物检测
Carbohydrates are made of simple sugars (monosaccharides) such as glucose. Starch and glycogen are polysaccharides used for energy storage. Cellulose is a structural polysaccharide in plant cell walls.
碳水化合物由单糖（单糖类）如葡萄糖组成。淀粉和糖原是多糖，用于储能。纤维素是植物细胞壁中的结构多糖。
Lipids are fats and oils, made of fatty acids and glycerol. They provide insulation and long-term energy storage.
脂质是脂肪和油，由脂肪酸和甘油组成。它们提供绝缘和长期能量储存。
Proteins are made of long chains of amino acids. They form enzymes, hormones, antibodies and structural components.
蛋白质由氨基酸长链构成。它们形成酶、激素、抗体和结构组分。
DNA is the genetic material, a double helix of nucleotides carrying the code for protein synthesis.
DNA 是遗传物质，是核苷酸组成的双螺旋，携带蛋白质合成密码。
| Test (English) | 检测 (中文) | Positive result (English) | 阳性结果 (中文) |
|---|---|---|---|
| Benedict's test for reducing sugars (glucose) | 本尼迪克特试剂检测还原糖（葡萄糖） | Heat; brick-red precipitate | 加热；砖红色沉淀 |
| Iodine test for starch | 碘液检测淀粉 | Blue-black colour | 蓝黑色 |
| Biuret test for protein | 双缩脲试剂检测蛋白质 | Mauve/purple colour | 紫红色/紫色 |
| Ethanol emulsion test for lipids | 乙醇乳化法检测脂质 | Cloudy white emulsion | 乳白色浑浊 |
4. Enzymes | 酶
lysts → Proteins → Lock-and-key model → Factors (temperature, pH, substrate concentration)
思维导图节点：酶 → 生物催化剂 → 蛋白质 → 锁钥模型 → 影响因素（温度、pH、底物浓度）
Enzymes are protein molecules that speed up chemical reactions without being used up. Each enzyme has an active site with a specific shape that fits a specific substrate, like a lock and key.
酶是蛋白质分子，能加快化学反应而本身不被消耗。每种酶有一个特定形状的活性部位，正好与特定底物契合，就像锁和钥匙。
At low temperatures, enzyme activity is slow. As temperature rises, activity increases until an optimum is reached. Above the optimum, the enzyme denatures: its active site changes shape irreversibly and activity drops sharply.
低温下酶活性低。温度升高时活性上升，直至达到最适温度。超过最适温度后酶变性：活性部位形状不可逆改变，活性急剧下降。
Enzymes also have an optimum pH. Extreme pH values denature the enzyme. Substrate concentration: as substrate concentration increases, rate of reaction increases until all active sites are occupied (saturation).
酶也有最适 pH。极端 pH 会使酶变性。底物浓度：随着底物浓度增加，反应速率加快，直到所有活性部位都被占据（饱和）。
Think of the mind map branch: 'Denaturation = shape loss → no function'.
思维导图分支：“变性 = 形状丧失 → 没有功能”。
5. Movement Across Membranes | 跨膜运输
Mind map node: Membrane transport → Diffusion, Osmosis, Active transport
思维导图节点：跨膜运输 → 扩散、渗透、主动运输
| Process (English) | 过程 (中文) | Description (English) | 描述 (中文) |
|---|---|---|---|
| Diffusion | 扩散 | Net movement of particles from a region of higher concentration to a region of lower concentration down a concentration gradient. Passive; no energy required. | 微粒沿浓度梯度从高浓度区向低浓度区的净移动。被动，不耗能。 |
| Osmosis | 渗透 | Net movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane. | 水分子通过部分透性膜从水势高处向水势低处的净移动。 |
| Active transport | 主动运输 | Movement of particles against a concentration gradient using energy from respiration (ATP) and carrier proteins. | 利用呼吸作用释放的能量（ATP）和载体蛋白逆浓度梯度移动微粒。 |
In plants, water enters root hair cells by osmosis, and mineral ions are taken up by active transport. In animals, glucose is absorbed by active transport in the small intestine.
在植物中，水分通过渗透进入根毛细胞，矿质离子通过主动运输吸收。在动物中，葡萄糖在小肠通过主动运输被吸收。
6. Photosynthesis and Plant Nutrition | 光合作用与植物营养
→ Word equation → Balanced equation → Limiting factors → Leaf adaptations → Mineral needs
思维导图节点：光合作用 → 文字方程式 → 平衡方程式 → 限制因子 → 叶片适应 → 矿物质需求
tion: Carbon dioxide + water → glucose + oxygen, in the presence of light and chlorophyll.
文字方程式：二氧化碳 + 水 → 葡萄糖 + 氧气，在光和叶绿素存在下。
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
Limiting factors: light intensity, carbon dioxide concentration, and temperature. Any one of these can limit the rate of photosynthesis when in short supply.
限制因子：光照强度、二氧化碳浓度和温度。其中任何一个在供应不足时都会限制光合作用速率。
Leaf structure is adapted for photosynthesis: broad lamina to capture light, thin to allow rapid gas exchange, air spaces and stomata for CO₂ entry, palisade cells packed with chloroplasts.
叶片结构适应光合作用：宽阔的叶身捕捉光照，薄叶片便于快速气体交换，细胞间隙和气孔让 CO₂ 进入，栅栏组织细胞充满叶绿体。
Plants need mineral ions: nitrate ions (NO₃⁻) for making amino acids and proteins; magnesium ions (Mg²⁺) for chlorophyll molecules. Deficiency leads to stunted growth and yellowing leaves (chlorosis).
植物需要矿质离子：硝酸根离子 (NO₃⁻) 用于合成氨基酸和蛋白质；镁离子 (Mg²⁺) 用于合成叶绿素分子。缺乏会导致生长受阻和叶片黄化。
7. Human Nutrition and Digestion | 人体营养与消化
Human digestive system → Alimentary canal organs → Digestive enzymes → Absorption → Villi
思维导图节点：人体消化系统 → 消化道器官 → 消化酶 → 吸收 → 绒毛
Mouth: mechanical digestion by teeth; salivary amylase begins starch breakdown.
口腔：牙齿进行物理性消化；唾液淀粉酶开始分解淀粉。
Oesophagus: tube that pushes food down by peristalsis.
食道：通过蠕动将食物向下推送的管道。
Stomach: produces protease (pepsin) and hydrochloric acid to kill bacteria and provide optimum pH for pepsin.
胃：产生蛋白酶（胃蛋白酶）和盐酸，杀死细菌并为胃蛋白酶提供最适 pH。
Small intestine: main site of digestion and absorption. Pancreatic amylase, protease and lipase act here; bile from liver emulsifies fats. Products absorbed into blood or lymph.
小肠：消化和吸收的主要部位。胰淀粉酶、蛋白酶和脂肪酶在此起作用；肝脏分泌的胆汁乳化脂肪。消化产物被吸收进入血液或淋巴。
Villi in the small intestine: finger-like projections with thin epithelium (one cell thick), rich blood capillary network, and a lacteal (lymph vessel). These features increase surface area and speed up absorption.
小肠绒毛：指状突起，只有一层细胞厚的上皮，丰富的毛细血管网和一根乳糜管（淋巴管）。这些特征增大表面积，加快吸收。
8. Transport Systems in Animals and Plants | 动植物运输系统
l transport → Heart, Blood vessels, Blood → Plant transport → Xylem, Phloem, Transpiration
思维导图节点：动物运输 → 心脏、血管、血液 → 植物运输 → 木质部、韧皮部、蒸腾作用
The heart: muscular pump with four chambers (right atrium, right ventricle, left atrium, left ventricle). The right side pumps deoxygenated blood to the lungs; the left side pumps oxygenated blood to the body.
心脏：肌肉泵，四个腔室（右心房、右心室、左心房、左心室）。右心把乏氧血泵至肺部；左心把富氧血泵至全身。
Blood vessels: Arteries carry blood away from the heart under high pressure (thick elastic walls); veins carry blood back (valves prevent backflow); capillaries are one-cell thick to allow exchange.
血管：动脉把血液从心脏带出，压力高（壁厚而有弹性）；静脉把血液送回（有瓣膜防止倒流）；毛细血管壁仅一层细胞厚，利于交换。
Blood components: Red blood cells (haemoglobin, transport O₂), white blood cells (defence), platelets (clotting), plasma (transports dissolved substances and heat).
血液成分：红细胞（血红蛋白，运输 O₂）、白细胞（防御）、血小板（凝血）、血浆（运输溶解物和热量）。
In plants, xylem vessels transport water and mineral ions from roots to leaves, supported by transpiration pull. Phloem transports sucrose and amino acids (translocation) from sources to sinks.
在植物中，木质部导管把水和矿质离子由根运至叶，依靠蒸腾拉力。韧皮部把蔗糖和氨基酸从源运到库（转运作用）。
Transpiration: loss of water vapour from leaf surface, mainly through stomata. Rate increases with higher temperature, lower humidity, wind and light.
蒸腾作用：水蒸气从叶表面散失，主要通过气孔。温度升高、湿度降低、有风、有光时速率加快。
9. Coordination and Response | 协调与反应
ystem → Reflex arc, Synapses → Hormones → Adrenaline, Insulin → Plant responses → Tropisms
思维导图节点：神经系统 → 反射弧、突触 → 激素 → 肾上腺素、胰岛素 → 植物反应 → 向性
urone → relay neurone (CNS) → motor neurone → effector (muscle/gland). Rapid, involuntary.
神经系统利用电冲动沿神经元传导。反射弧：刺激 → 感受器 → 感觉神经元 → 中间神经元（CNS）→ 运动神经元 → 效应器（肌肉/腺体）。快速、不自主。
At a synapse, an impulse triggers the release of neurotransmitter (e.g. acetylcholine), which diffuses across the gap and starts a new impulse in the next neurone. Synapses ensure one-way transmission.
在突触处，冲动引发神经递质（如乙酰胆碱）释放，递质扩散通过间隙并在下一个神经元启动新冲动。突触保证单向传递。
Adrenaline: hormone released from adrenal glands in 'fight or flight' situations. It increases heart rate, breathing rate, and blood glucose concentration.
肾上腺素：肾上腺在“战斗或逃跑”时释放的激素。它提高心率、呼吸频率和血糖浓度。
Insulin: hormone from the pancreas that lowers blood glucose level by converting glucose to glycogen in the liver. Diabetes (Type 1) results from insufficient insulin.
胰岛素：由胰腺分泌，通过将葡萄糖转化为肝糖原降低血糖水平。一型糖尿病因胰岛素不足引起。
Plants respond to light (phototropism) and gravity (geotropism). Shoots grow towards light (positive phototropism) and roots grow towards gravity (positive geotropism), controlled by auxin distribution.
植物对光（向光性）和重力（向地性）作出反应。茎向光生长（正向光性），根向重力方向生长（正向地性），受生长素分布控制。
10. Reproduction and Inheritance | 生殖与遗传
Asexual vs Sexual → Flower structure → Pollination → DNA & Genes → Monohybrid inheritance
思维导图节点：生殖 → 无性 vs 有性 → 花的结构 → 传粉 → DNA & 基因 → 单基因遗传
Asexual reproduction produces genetically identical offspring from one parent (e.g. binary fission in bacteria, runners in strawberries). Sexual reproduction involves the fusion of gametes, producing variation.
无性生殖由一个亲本产生遗传相同的后代（如细菌分裂、草莓匍匐茎）。有性生殖涉及配子融合，产生变异。
Flower structure: sepals protect the bud; petals attract pollinators; stamens (anther + filament) are male parts producing pollen; carpels (stigma, style, ovary) are female parts containing ovules.
花的结构：萼片保护花蕾；花瓣吸引传粉者；雄蕊（花药+花丝）为雄性部分，产生花粉；雌蕊（柱头、花柱、子房）为雌性部分，内含胚珠。
Pollination is the transfer of pollen from anther to stigma. Cross-pollination increases variation. Fertilisation: pollen tube grows down the style, male gamete fuses with female gamete in ovule to form zygote.
传粉是花粉由花药传到柱头。异花传粉增加变异。受精：花粉管向下穿过花柱，雄配子与胚珠中的雌配子结合形成合子。
DNA is a double helix; a gene is a section of DNA coding for a protein. Alleles are different versions of a gene. Dominant alleles mask recessive ones.
DNA 为双螺旋；基因是编码蛋白质的一段 DNA。等位基因是基因的不同版本。显性等位基因掩盖隐性等位基因。
Monohybrid cross: for a single gene. Use a Punnett square. If T =
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