📚 IGCSE WJEC Biotechnology Revision Guide | IGCSE WJEC 生物技术考点精讲
Biotechnology uses living organisms or biological processes to develop useful products, spanning everything from bread-making to cutting-edge genetic engineering. In the WJEC IGCSE Biology specification, this topic examines both traditional and modern applications, helping you understand how microorganisms, enzymes, and genetic modification contribute to medicine, food production, and sustainable development.
生物技术利用活生物体或生物过程来开发有用的产品，涵盖从制作面包到尖端基因工程的所有内容。在 WJEC IGCSE 生物大纲中，本主题探讨传统与现代的应用，帮助你理解微生物、酶和遗传修饰如何促进医药、食品生产和可持续发展。
1. What is Biotechnology? | 什么是生物技术？
Biotechnology is the application of biology to solve problems and make useful products. It involves using living cells, enzymes, or whole organisms to carry out processes on an industrial scale. The term covers both ancient practices like fermentation and modern techniques such as genetic modification.
生物技术是应用生物学来解决问题并制造有用产品。它涉及利用活细胞、酶或整个生物体在工业规模上进行生产。这一术语既涵盖发酵等古老实践，也包括基因修饰等现代技术。
In WJEC exams, you must distinguish between 'traditional biotechnology' (using organisms without altering their DNA) and 'modern biotechnology' (manipulating genes directly). Examples of traditional biotechnology include yoghurt and bread production, while modern biotechnology includes insulin manufacture and GM crops.
在 WJEC 考试中，你必须区分“传统生物技术”（在不改变其 DNA 的情况下利用生物体）和“现代生物技术”（直接操作基因）。传统生物技术的例子包括酸奶和面包生产，而现代生物技术则包括胰岛素制造和转基因作物。
2. Traditional Biotechnology: Fermentation | 传统生物技术：发酵
Fermentation is a metabolic process where microorganisms convert sugars into acids, gases, or alcohol in the absence of oxygen. This anaerobic respiration is exploited to produce foods and drinks. For IGCSE, focus on two key organisms: yeast and bacteria.
发酵是一种代谢过程，微生物在无氧条件下将糖转化为酸、气体或酒精。这种无氧呼吸被用来生产食品和饮料。对于 IGCSE，重点放在两种关键生物上：酵母和细菌。
The word equation for fermentation in yeast is: Glucose → Ethanol + Carbon dioxide (+ energy). This reaction is carried out by the enzyme zymase naturally present in yeast cells. It is vital for beer, wine, and bread making.
酵母发酵的文字方程为：葡萄糖 → 乙醇 + 二氧化碳（+ 能量）。该反应由酵母细胞中天然存在的酒化酶执行。这对啤酒、葡萄酒和面包制作至关重要。
3. Yeast in Bread and Alcohol Production | 酵母在面包和酒精生产中的作用
In baking, yeast is mixed with flour and water. Enzymes in the dough break down starch into sugars, which the yeast ferments. The carbon dioxide produced forms bubbles, causing the dough to rise. The ethanol evaporates during baking, leaving the soft texture of bread.
在烘焙中，酵母与面粉和水混合。面团中的酶将淀粉分解为糖，然后酵母进行发酵。产生的二氧化碳形成气泡，使面团膨胀。乙醇在烘焙过程中蒸发，留下面包的松软质地。
For alcoholic beverages, yeast is grown in sugary solutions under anaerobic conditions. In beer making, malted barley provides sugars; in wine production, grape juice is used. The ethanol remains in the liquid, and the concentration can be increased by distillation for spirits.
对于酒精饮料，酵母在无氧条件下的含糖溶液中生长。在啤酒酿造中，发芽大麦提供糖；在葡萄酒生产中，使用葡萄汁。乙醇保留在液体中，对于烈酒可通过蒸馏提高浓度。
Ensure you can state the conditions required: a source of sugar, warm temperature (around 30°C for yeast), the absence of oxygen, and a slightly acidic pH. Contamination by unwanted microbes must be prevented by sterilising equipment.
确保你可以说明所需条件：糖源、温暖温度（酵母约 30°C）、无氧环境以及弱酸性 pH。必须通过设备消毒来防止有害微生物污染。
4. Bacterial Fermentation: Yoghurt Making | 细菌发酵：酸奶制作
Yoghurt is produced by fermenting milk with specific bacteria, usually Lactobacillus bulgaricus and Streptococcus thermophilus. These bacteria respire anaerobically, converting lactose (milk sugar) into lactic acid.
酸奶是通过特定细菌（通常是保加利亚乳杆菌和嗜热链球菌）发酵牛奶制成的。这些细菌进行无氧呼吸，将乳糖（牛奶中的糖）转化为乳酸。
The lactic acid lowers the pH, causing milk proteins to denature and coagulate, thickening the milk into yoghurt. The acidic environment also inhibits the growth of spoilage bacteria, acting as a natural preservative. In WJEC, you should describe the process: pasteurise milk, cool to 40-45°C, add bacterial culture, and incubate for several hours.
乳酸降低 pH，使牛奶蛋白变性并凝固，将牛奶增稠为酸奶。酸性环境还抑制腐败细菌的生长，起到天然防腐的作用。在 WJEC 中，你应描述该过程：对牛奶进行巴氏消毒，冷却至 40-45°C，加入细菌培养物，并保温数小时。
The reaction can be summarised as: Lactose → Lactic acid. No gas is produced, so the product stays smooth. This contrasts with yeast fermentation, where CO₂ is released.
反应可总结为：乳糖 → 乳酸。不产生气体，因此产品保持细腻。这与酵母发酵释放 CO₂ 形成对比。
5. Industrial Microbial Production | 工业微生物生产
On a large scale, microbes are grown in fermenters (bioreactors) to produce antibiotics, enzymes, and other chemicals. The classic example is penicillin production from the mould Penicillium chrysogenum. The fungus is grown in a nutrient medium with controlled aeration, pH, and temperature.
大规模上，微生物在发酵罐（生物反应器）中生长，以生产抗生素、酶和其他化学物质。经典例子是从产黄青霉中生产青霉素。该真菌在营养培养基中生长，并控制通气、pH 和温度。
Key parts of a fermenter include: a stirrer to keep cells in suspension and distribute nutrients, an air inlet with a filter to provide sterile oxygen, a cooling jacket to remove metabolic heat, and sensors for pH and temperature. Aseptic technique is crucial to prevent contamination.
发酵罐的关键部件包括：搅拌器以保持细胞悬浮并分布营养物、带有过滤器的空气入口以提供无菌氧气、冷却夹套去除代谢热，以及 pH 和温度传感器。无菌技术对于防止污染至关重要。
In batch culture, nutrients are added at the start and the product is harvested at the end. In continuous culture, fresh medium is constantly added while product is removed, allowing steady production. WJEC may ask you to interpret graphs of growth phases (lag, log, stationary, death).
在分批培养中，开始时加入营养物质，结束时收获产品。在连续培养中，不断添加新鲜培养基并移除产品，从而实现稳定生产。WJEC 可能要求你解读生长阶段（延滞期、对数期、稳定期、衰亡期）的图表。
6. Enzyme Biotechnology | 酶生物技术
Enzymes are biological catalysts widely used in industry because they work at low temperatures, reduce energy costs, and can be specific to substrates. They are often immobilised by attaching them to inert materials, allowing reuse and continuous processing.
酶是广泛用于工业的生物催化剂，因为它们可在低温下工作、降低能源成本且对底物具有特异性。它们通常通过固定在惰性材料上来进行固定化，从而可重复使用和进行连续处理。
The table below summarises key enzymes and their applications frequently tested in IGCSE WJEC:
下表总结了 IGCSE WJEC 中常考的关键酶及其应用：
| Enzyme | Source | Application | Details |
|---|---|---|---|
| Protease | Bacteria | Biological washing powders | Breaks down protein stains like blood and egg at low temperatures. |
| Glucose isomerase | Bacteria | High-fructose corn syrup | Converts glucose into sweeter fructose for soft drinks. |
| Pectinase | Fungi | Fruit juice extraction | Breaks down pectin in cell walls, increasing juice yield and clarity. |
| Chymosin | GM yeast | Cheese-making | Coagulates milk to form curds; vegetarian-friendly alternative to rennet. |
| Lactase | Yeast | Lactose-free milk | Hydrolyses lactose into glucose and galactose for lactose-intolerant individuals. |
Immobilised enzyme systems, such as using alginate beads, allow the enzyme to be recovered and reused. WJEC expects you to evaluate advantages: reducing cost, continuous flow-through processes, and no enzyme in the final product.
固定化酶系统，例如使用藻酸盐珠，允许酶被回收和重复使用。WJEC 希望你评价其优势：降低成本、连续流通工艺，以及产品中无酶残留。
7. Genetic Engineering Basics | 基因工程基础
Genetic engineering, a cornerstone of modern biotechnology, involves altering the DNA of an organism by inserting new genes. The basic toolkit includes restriction enzymes that cut DNA at specific sequences, leaving 'sticky ends', and DNA ligase that joins fragments together.
基因工程是现代生物技术的基石，它通过插入新基因来改变生物的 DNA。基本工具包包括在特定序列处切割 DNA 并留下“粘性末端”的限制酶，以及将片段连接在一起的 DNA 连接酶。
Vectors, such as bacterial plasmids, carry the desired gene into the host cell. Plasmids are small, circular DNA molecules found in bacteria. The same restriction enzyme must be used to cut the plasmid and the target gene to create complementary sticky ends, allowing the gene to be spliced in.
载体，如细菌质粒，将目标基因携带进宿主细胞。质粒是细菌中发现的小型环状 DNA 分子。必须使用相同的限制酶切割质粒和靶基因，以产生互补的粘性末端，使基因能被拼接进去。
The steps: isolate the gene, cut it and the plasmid with restriction enzyme, anneal the gene into the plasmid using DNA ligase to form recombinant DNA, insert the recombinant plasmid into a host cell, and select cells that have taken up the gene using a marker (e.g., antibiotic resistance).
步骤：分离基因，用限制酶切割基因和质粒，用 DNA 连接酶将基因退火进入质粒形成重组 DNA，将重组质粒插入宿主细胞，并使用标记（如抗生素抗性）筛选已摄取基因的细胞。
8. Producing Human Insulin | 生产人胰岛素
Before genetic engineering, diabetics relied on insulin extracted from animal pancreases, which could cause allergic reactions. Today, human insulin is produced by bacteria containing the human insulin gene. The human gene for insulin is inserted into a plasmid, which is taken up by Escherichia coli.
在基因工程之前，糖尿病患者依赖从动物胰腺提取的胰岛素，这可能引起过敏反应。如今，人胰岛素由含有人胰岛素基因的细菌生产。人胰岛素基因被插入质粒，然后被大肠杆菌摄取。
The transgenic bacteria are grown in fermenters, and they secrete insulin identical to human insulin. After purification, it is safe and effective. You should be able to compare the sources: recombinant insulin is purer, faster-acting, and can be produced in large quantities without ethical concerns about animal sourcing.
转基因细菌在发酵罐中生长，它们分泌与人胰岛素完全相同的胰岛素。纯化后安全有效。你应该能够比较来源：重组胰岛素更纯、起效更快、可大量生产，且没有动物来源的伦理顾虑。
This is a staple WJEC question: outline the stages and explain why it is an improvement. Ensure you use precise terminology: recombinant DNA, plasmid vector, restriction endonuclease, transformed bacteria.
这是 WJEC 的常见考题：概述各阶段并解释为什么这是一种改进。确保使用精确的术语：重组 DNA、质粒载体、限制性内切酶、转化细菌。
9. Genetically Modified Crops | 转基因作物
GM crops have had genes from other organisms introduced to give them desirable traits. Common examples include Bt maize, which produces an insecticidal toxin from the bacterium Bacillus thuringiensis, and herbicide-tolerant soybeans that survive applications of glyphosate.
转基因作物引入了来自其他生物的基因以获得理想性状。常见例子包括产生来自苏云金芽孢杆菌的杀虫毒素的 Bt 玉米，以及耐受草甘膦喷洒的抗除草剂大豆。
Golden Rice is another key example: it has been engineered with genes from daffodil and bacteria to produce beta-carotene, a precursor of vitamin A, aimed at reducing vitamin A deficiency in developing countries.
黄金大米是另一个关键例子：它被导入了来自水仙和细菌的基因以产生 β-胡萝卜素（维生素 A 的前体），旨在减少发展中国家的维生素 A 缺乏症。
For WJEC, you must weigh potential benefits (higher yields, reduced pesticide use, improved nutritional content) against risks (unintended effects on other organisms, allergenicity, gene flow to wild relatives, and the development of pest resistance). You may be asked to analyse data on crop yields or biodiversity.
对于 WJEC，你必须权衡潜在益处（更高产量、减少杀虫剂使用、改善营养成分）与风险（对其他生物的非预期效应、过敏风险、基因流向野生近缘种，以及害虫抗性的产生）。你可能会被要求分析作物产量或生物多样性的数据。
10. Biofuels and Sustainability | 生物燃料与可持续发展
Biotechnology contributes to sustainable energy through biofuels. Bioethanol is produced by fermenting sugars from crops such as maize or sugarcane with yeast. Biogas, mainly methane, is generated by anaerobic digestion of waste by bacteria. These are renewable but must replace a significant proportion of fossil fuels to reduce greenhouse gas emissions.
生物技术通过生物燃料为可持续能源做出贡献。生物乙醇通过用酵母发酵玉米或甘蔗等作物的糖来生产。沼气，主要是甲烷，由细菌通过厌氧消化废弃物产生。这些燃料是可再生的，但必须替代相当比例的化石燃料才能减少温室气体排放。
WJEC often links biogas production to the carbon cycle and types of waste that can be used. A simple biogas generator involves feeding organic waste into a digester where methanogenic bacteria thrive in warm, oxygen-free conditions. The methane can be burned for heating or electricity.
WJEC 经常将沼气生产与碳循环以及可利用的废弃物类型联系起来。一个简单的沼气发生器是将有机废弃物送入消化器，产甲烷菌在温暖、无氧条件下繁殖。产生的甲烷可以燃烧用于供暖或发电。
However, there are conflicts: land used for biofuel crops may compete with food production, leading to higher food prices and deforestation. This 'food vs fuel' debate is a common evaluation point. For the exam, be prepared to discuss sustainability from social, economic, and environmental perspectives.
然而，也存在冲突：用于生物燃料作物的土地可能与粮食生产竞争，导致粮食价格上涨和森林砍伐。这种“粮食与燃料”的争论是常见的评价点。为考试做好准备，从社会、经济和环境角度讨论可持续性。
11. Ethical Considerations | 伦理考量
Modern biotechnology raises significant ethical issues. Genetic modification is seen by some as 'playing God', and there are concerns about long-term health effects, potential for 'designer babies', and animal welfare in cloning. WJEC requires you to appreciate multiple viewpoints.
现代生物技术引发了重大伦理问题。一些人认为基因修饰是“扮演上帝”，并且存在对长期健康影响、“设计婴儿”的潜力以及克隆中动物福利的担忧。WJEC 要求你理解多种观点。
In agriculture, GM seeds are often patented by large corporations, meaning farmers in low-income countries may become dependent on them. The risk of cross-pollination between GM and non-GM crops threatens organic farming and natural biodiversity. Governments regulate field trials and labelling, but public acceptance varies.
在农业方面，转基因种子通常由大公司申请专利，这意味着低收入国家的农民可能对其产生依赖。转基因与非转基因作物之间异花授粉的风险威胁着有机农业和自然生物多样性。政府监管田间试验和标签，但公众接受度各不相同。
You should be able to construct balanced arguments, using scientific knowledge to support your reasoning. For instance, while Bt crops reduce chemical pesticide use, they could harm non-target insects like butterflies. Always link your discussion to evidence and the precautionary principle.
你应该能够构建平衡的论点，运用科学知识支持你的推理。例如，虽然 Bt 作物减少了化学杀虫剂的使用，但它们可能伤害蝴蝶等非目标昆虫。始终将你的讨论与证据和预防原则联系起来。
Published by TutorHao | Biology Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图