📚 GCSE WJEC Biology: Biotechnology Revision Essentials | GCSE WJEC 生物：生物技术 考点精讲
Biotechnology harnesses living organisms and their enzymes to create products and processes that benefit humanity. From the ancient arts of bread-making and brewing to modern genetic engineering, this field is central to WJEC GCSE Biology. Understanding how microorganisms work, how we control their growth in fermenters, and how we manipulate DNA will not only prepare you for exam questions but also reveal the science behind everyday items like insulin, washing powders, and yoghurt.
生物技术利用活生物体及其酶来制造造福人类的产品和过程。从古老的面包烘焙和酿造技艺到现代基因工程，这个领域是 WJEC GCSE 生物学的核心。了解微生物如何工作、我们如何在发酵罐中控制它们的生长，以及我们如何操控 DNA，不仅能帮你备考，还能揭示胰岛素、洗衣粉、酸奶等日常物品背后的科学。
1. What Is Biotechnology? | 什么是生物技术？
Biotechnology is the application of living organisms, systems or processes to manufacture useful products or to perform tasks for humans. It ranges from the traditional use of yeast in baking to cutting-edge genetic modification.
生物技术是应用活生物体、系统或过程来制造有用产品或是为人类执行任务。它从传统的在烘焙中使用酵母，到尖端的基因改造不等。
In the WJEC specification, biotechnology is often split into traditional (using whole microorganisms) and modern (genetic engineering and enzyme technology). Both rely on the metabolism of cells.
在 WJEC 考纲中，生物技术常被分为传统（利用整个微生物）和现代（基因工程与酶技术）。两者都依赖细胞的代谢作用。
2. Microorganisms: The Workhorses of Biotechnology | 微生物：生物技术的劳模
Microorganisms such as bacteria and fungi are widely used because they grow rapidly, are easy to culture on a large scale, and can produce complex molecules that we need.
细菌和真菌等微生物被广泛使用，因为它们生长迅速、易于大规模培养，并且能生产我们所需的复杂分子。
For example, the bacterium Lactobacillus is used to make yoghurt, while the fungus Saccharomyces cerevisiae (yeast) is essential for bread and alcoholic drinks. Their metabolic pathways are at the heart of bio-manufacturing.
例如，乳酸菌用于制作酸奶，而真菌酿酒酵母对面包和酒精饮品至关重要。它们的代谢途径是生物制造的核心。
Key advantage: They can be genetically engineered to produce substances like human insulin, which they would not naturally make.
关键优势：它们可以被基因工程改造，来生产诸如人胰岛素之类其天然并不产生的物质。
3. Fermentation - Anaerobic Respiration in Yeast | 发酵——酵母的无氧呼吸
Fermentation is the process by which yeast breaks down glucose in the absence of oxygen, releasing energy and producing ethanol and carbon dioxide. The word equation is:
发酵是酵母在没有氧气的情况下分解葡萄糖，释放能量并产生乙醇和二氧化碳的过程。文字方程式为：
Glucose → Ethanol + Carbon dioxide (+ energy)
葡萄糖 → 乙醇 + 二氧化碳（+ 能量）
C₂H₅OH + 2CO₂. This anaerobic respiration is irreversible in yeast cells and is commercially exploited for beverages and biofuels.
用化学式表示为：C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂。这种无氧呼吸在酵母细胞中是不可逆的，并被商业上用于饮料和生物燃料。
The alcohol produced can be distilled to make spirits, while the CO₂ makes dough rise. Enzymes within yeast catalyse every step of this pathway.
产生的酒精可通过蒸馏制成烈酒，而二氧化碳则让面团膨胀。酵母内的酶催化了该途径的每一步。
4. Making Bread | 制作面包
Bread-making is a classic traditional biotechnology. Yeast is mixed with flour, water and a little sugar. The yeast ferments the sugars, releasing carbon dioxide gas.
面包制作是经典的传统生物技术。酵母与面粉、水和少量糖混合。酵母发酵糖类，释放二氧化碳气体。
The CO₂ bubbles get trapped in the stretchy gluten network of the dough, causing it to rise. This gives bread its soft, spongy texture.
二氧化碳气泡被困在面团有弹性的面筋网络中，使其膨胀。这赋予了面包柔软、海绵般的质地。
During baking, the high temperature kills the yeast and evaporates any ethanol produced, so the final loaf is non-alcoholic. The heat also sets the dough structure.
在烘焙过程中，高温杀死酵母并蒸发掉产生的乙醇，所以最终的面包不含酒精。热量也固定了面团结构。
WJEC often asks why dough is left in a warm place: to provide the optimum temperature (around 25–30°C) for yeast enzymes to work efficiently.
WJEC 常问为什么要将面团放在温暖的地方：为酵母酶提供最适温度（大约25–30°C）以使其高效工作。
5. Brewing Beer | 酿造啤酒
Beer brewing begins with barley grains that are allowed to germinate (malting). This activates enzymes that break down starch into maltose, a sugar yeast can use.
啤酒酿造始于让大麦粒发芽（制麦）。这激活了将淀粉分解为麦芽糖的酶，麦芽糖是酵母可利用的糖。
The malted barley is then crushed and mixed with warm water (mashing) to allow the enzymes to convert more starch into sugars. The sugary liquid, called wort, is boiled with hops for flavour and to sterilise it.
然后将麦芽碾碎并与温水混合（糖化），让酶将更多淀粉转化为糖。这种含糖液体称为麦芽汁，与啤酒花一起煮沸，以增加风味并灭菌。
After cooling, yeast is added and fermentation begins. The yeast converts sugars to ethanol and CO₂. The specific yeast strain and conditions determine the beer type (ale, lager).
冷却后加入酵母，发酵开始。酵母将糖转化为乙醇和二氧化碳。特定的酵母菌株和条件决定了啤酒的类型（艾尔、拉格）。
Hops provide bitterness and act as a natural preservative. The alcohol content is controlled by the sugar concentration and fermentation time.
啤酒花提供苦味并作为天然防腐剂。酒精含量由糖浓度和发酵时间控制。
6. Producing Yoghurt | 酸奶生产
Yoghurt is made by fermenting milk with bacteria, typically Lactobacillus bulgaricus and Streptococcus thermophilus. These bacteria carry out lactic acid fermentation.
酸奶是通过用细菌发酵牛奶制成的，通常是保加利亚乳杆菌和嗜热链球菌。这些细菌进行乳酸发酵。
They convert lactose (milk sugar) into lactic acid. The lactic acid lowers the pH, causing milk proteins (casein) to denature and coagulate, thickening the milk into yoghurt.
它们将乳糖转化为乳酸。乳酸降低pH值，导致牛奶蛋白（酪蛋白）变性并凝固，使牛奶变稠成为酸奶。
The process involves pasteurising the milk first to kill any unwanted microorganisms, then cooling it and adding the starter culture. The mixture is incubated at around 40–45°C for several hours.
该过程首先对牛奶进行巴氏消毒以杀死任何有害微生物，然后冷却并加入发酵剂。混合物在约40–45°C下保温数小时。
The sour taste comes from lactic acid, and the final product contains live bacteria that can be beneficial for gut health (probiotics).
酸味来自乳酸，最终产品含有对肠道健康有益的活菌（益生菌）。
7. Industrial Fermenters and Controlling Growth | 工业发酵罐与生长控制
To produce large quantities of microbial products (e.g. antibiotics, enzymes, biofuels), industry uses vessels called fermenters. The conditions inside are carefully monitored and adjusted.
为了生产大量的微生物产品（如抗生素、酶、生物燃料），工业上使用称为发酵罐的容器。其内部条件被仔细监控和调整。
A typical fermenter has a sterile air supply (if the process is aerobic), a stirrer to evenly mix nutrients and oxygen, a water jacket for temperature control, and probes for pH and temperature.
典型的发酵罐有灭菌空气供应（若过程需氧）、搅拌器以均匀混合营养物和氧气、用于控温的水套，以及pH和温度探头。
The key conditions to control are:
要控制的关键条件有：
| Condition | Reason |
|---|---|
| Temperature (e.g. 30°C for yeast, 25°C for penicillin mould) | Avoids denaturing enzymes; maximises growth rate. Too high kills microbes, too low slows metabolism. |
| pH (often near neutral or slightly acidic) | Enzymes have an optimum pH; deviation reduces activity. Lactic acid bacteria prefer lower pH. |
| Oxygen supply (aerobic processes) | Provides oxygen for aerobic respiration, which yields more ATP for rapid growth. |
| Nutrient concentration (carbohydrates, nitrogen sources) | Ensures microbes have raw materials for growth and product synthesis. Too little limits yield; too much may inhibit. |
| Sterility | Prevents contamination by other microbes that could compete or produce toxins. |
For anaerobic processes (e.g. ethanol fermentation), oxygen is kept out to prevent microbes switching to aerobic respiration, which would stop alcohol production.
对于厌氧过程（如乙醇发酵），排除氧气以防止微生物转向有氧呼吸，那会中止酒精生产。
8. Genetic Engineering Basics | 基因工程基础
Genetic engineering allows scientists to transfer a gene from one organism into another, enabling the recipient to produce a protein it could not make before.
基因工程使科学家能将一个基因从一个生物体转移到另一个生物体中，使受体能够生产以前无法制造的蛋白质。
The technique involves cutting DNA at specific sequences using restriction enzymes to isolate the desired gene. The same enzyme cuts open a vector (often a bacterial plasmid), leaving complementary sticky ends.
该技术涉及使用限制性内切酶在特定序列处切割DNA以分离目标基因。相同的酶切开载体（通常是细菌质粒），留下互补的粘性末端。
The gene is inserted into the plasmid, and DNA ligase joins the sugar-phosphate backbones. The recombinant plasmid is then introduced into host cells (e.g. bacteria) by heat shock or other methods.
基因被插入质粒中，DNA连接酶连接糖-磷酸骨架。然后通过热激或其他方法将重组质粒引入宿主细胞（如细菌）。
Only bacteria that have taken up the plasmid are selected (often using antibiotic resistance markers), and those cells are cultured to produce the desired protein on a large scale.
只有吸收了质粒的细菌被筛选出来（常利用抗生素抗性标记），然后培养这些细胞以大规模生产所需的蛋白质。
9. Case Study: Bacterial Production of Human Insulin | 案例研究：细菌生产人胰岛素
Before genetic engineering, diabetics relied on insulin extracted from pig or cow pancreases, which could cause immune reactions. Now, bacteria produce human insulin that is identical to our own.
在基因工程之前，糖尿病患者依赖从猪或牛胰腺中提取的胰岛素，这可能导致免疫反应。现在，细菌生产出与人类自身完全相同的胰岛素。
The process: the human gene for insulin is isolated and inserted into a plasmid which is taken up by E. coli bacteria. The modified bacteria are grown in fermenters, secreting insulin that is then purified.
过程：分离出人胰岛素基因，插入到被大肠杆菌吸收的质粒中。改造后的细菌在发酵罐中生长，分泌出胰岛素，随后被纯化。
Advantages over animal insulin: exact match to human insulin, so fewer allergic reactions; unlimited supply; ethical acceptance (no animal slaughter).
与动物胰岛素相比的优势：与人胰岛素完全匹配，因此过敏反应更少；供应不受限；伦理上可接受（不涉及屠宰动物）。
WJEC may ask you to interpret diagrams of this process, including the role of restriction enzymes, sticky ends, and antibiotic selection of transformed bacteria.
WJEC 可能会要求你解释该过程的图解，包括限制性内切酶、粘性末端的作用，以及通过抗生素筛选转化细菌。
10. Genetically Modified (GM) Crops | 转基因作物
Genetic modification is also applied to plants to improve yields, nutritional content, or resistance to pests and herbicides. Common examples include Bt maize and Golden Rice.
基因改造也应用于植物，以提高产量、营养成分，或增强对害虫和除草剂的抗性。常见例子包括 Bt 玉米和金稻米。
Bt maize contains a gene from the bacterium Bacillus thuringiensis that produces a protein toxic to insect larvae. This reduces the need for chemical pesticides.
Bt 玉米含有来自苏云金芽孢杆菌的基因，该基因产生一种对昆虫幼虫有毒的蛋白质。这减少了对化学杀虫剂的需求。
Herbicide-resistant crops (e.g. Roundup Ready soya) allow farmers to spray fields to kill weeds without harming the crop. This can lead to no-till farming, reducing soil erosion.
抗除草剂作物（如抗农达大豆）允许农民喷洒除草剂杀灭杂草而不伤害作物。这可以促成免耕农业，减少土壤侵蚀。
Golden Rice is engineered to produce beta-carotene (a precursor of vitamin A) in the endosperm, aiming to combat vitamin A deficiency in regions relying on rice as a staple.
金稻米经过工程改造，在胚乳中产生β-胡萝卜素（维生素A的前体），旨在为解决以大米为主食地区的维生素A缺乏症。
Students should be able to discuss both the benefits (higher yield, less chemical use) and the potential risks (gene transfer to wild relatives, possible allergenicity, loss of biodiversity).
学生应能讨论好处（更高产量、减少化学品使用）和潜在风险（基因转移到野生近缘种、可能的过敏原性、生物多样性丧失）。
11. Enzyme Technology in Biotechnology | 生物技术中的酶技术
Isolated enzymes are used in many biotechnological processes because they work at low temperatures and pressures, are specific, and can be reused when immobilised.
分离的酶被用于许多生物技术过程中，因为它们能在低温和低压下工作，具有专一性，被固定化后还能重复使用。
In the food industry, pectinase is used to break down pectin in fruit pulp, increasing juice yield and clarity. Lactase converts lactose to glucose and galactose, producing lactose-free milk for intolerant individuals.
在食品工业中，果胶酶用于分解果肉中的果胶，提高出汁率和澄清度。乳糖酶将乳糖转化为葡萄糖和半乳糖，为乳糖不耐受者生产无乳糖牛奶。
Biological washing powders contain proteases and lipases that digest protein and fat stains at relatively low temperatures, saving energy.
生物洗衣粉含有蛋白酶和脂肪酶，可在相对低温下分解蛋白质和脂肪污渍，从而节省能源。
Immobilising enzymes in gel beads or on membranes allows continuous production, easy separation of product from enzyme, and makes the enzyme more stable.
将酶固定在凝胶珠或膜上可实现连续生产、产物与酶的简便分离，并使酶更稳定。
12. Ethical Issues and Sustainability | 伦理问题与可持续性
Modern biotechnology raises ethical questions. Genetic engineering of animals and plants is frequently debated: is it 'playing God', or a tool to solve food shortages?
现代生物技术引发了伦理问题。对动物和植物的基因工程常引发争论：这是“扮演上帝”，还是解决粮食短缺的工具？
GM crops must undergo rigorous safety testing for allergenicity and environmental impact before approval. Some people demand clear labelling of GM foods.
转基因作物在批准前必须经过严格的过敏原性和环境影响安全测试。有些人要求对转基因食品进行明确标注。
Sustainability can be enhanced by biotechnology: biofuels (bioethanol, biogas) from crop waste reduce reliance on fossil fuels. Bioremediation uses microbes to clean up oil spills and pollutants.
生物技术可增强可持续性：来自农作物废弃物的生物燃料（生物乙醇、沼气）减少了对化石燃料的依赖。生物修复利用微生物清理石油泄漏和污染物。
In WJEC exams, you should be able to present a balanced argument, citing evidence for both benefits and concerns, and link topics like fermentation, GM, and enzyme use to real-world applications.
在 WJEC 考试中，你应能够提出平衡的论点，引用好处与担忧的证据，并将发酵、转基因和酶的使用等主题与实际应用联系起来。
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