IGCSE OCR Biology: Biotechnology Revision | IGCSE OCR 生物：生物技术考点精讲

📚 IGCSE OCR Biology: Biotechnology Revision | IGCSE OCR 生物：生物技术考点精讲

Biotechnology is the use of living organisms (especially microorganisms) and their enzymes to produce useful products or carry out processes for human benefit. In the OCR IGCSE Biology specification, you need to understand key biotechnological applications such as fermentation, food production, antibiotic manufacture, genetic engineering, and the use of enzymes in industry. This article will guide you through every essential topic, with clear explanations in both English and Chinese.

生物技术是利用生物体（尤其是微生物）及其酶来生产有用产品或为人类利益进行某些过程的技术。在 OCR IGCSE 生物学大纲中，你需要掌握关键的生物技术应用，例如发酵、食品生产、抗生素制造、基因工程以及工业中酶的使用。本文将带你逐一攻克每个重要专题，提供中英双语清晰讲解。

1. What is Biotechnology? | 什么是生物技术？

Biotechnology is defined as the application of biological organisms, systems, or processes to manufacturing and service industries. It often involves the use of microorganisms such as bacteria and fungi, which can be grown quickly in fermenters under controlled conditions. The products range from food and drinks to medicines and fuels.

生物技术被定义为将生物有机体、系统或过程应用于制造和服务行业。它通常涉及利用细菌和真菌等微生物，这些微生物可以在发酵罐中在受控条件下快速生长。产品涵盖食品、饮料、药品到燃料。

At the IGCSE level, you must distinguish between ‘traditional’ biotechnology (like bread and yoghurt making) and ‘modern’ biotechnology (such as genetic modification). The core principle remains the same: we are harnessing the natural metabolic reactions of cells for our own purposes.

在 IGCSE 层面，你必须区分“传统”生物技术（如面包和酸奶制作）与“现代”生物技术（如基因改造）。其核心原理是相同的：我们利用细胞天然的代谢反应来实现自己的目的。

2. Microorganisms Used in Biotechnology | 生物技术中使用的微生物

The most commonly used microorganisms are bacteria and fungi. Bacteria such as Lactobacillus are used in making yoghurt, while the fungus Saccharomyces cerevisiae (yeast) is essential for bread and beer production. Another important fungus is Penicillium chrysogenum, which produces the antibiotic penicillin.

最常用的微生物是细菌和真菌。细菌如乳酸杆菌用于制造酸奶，而真菌酿母酵母（面包酵母）对于面包和啤酒生产至关重要。另一种重要真菌是产黄青霉，它产生抗生素青霉素。

These organisms are chosen because they grow rapidly on cheap nutrient sources, their waste products are often valuable, and they can be easily manipulated in a fermenter. In aerobic conditions, yeast respires to produce carbon dioxide and water; in anaerobic conditions, it ferments sugars to produce ethanol and carbon dioxide.

选择这些生物是因为它们能在廉价的营养源上快速生长，其废物往往很有价值，并且它们很容易在发酵罐中被操控。在有氧条件下，酵母进行呼吸产生二氧化碳和水；在无氧条件下，它发酵糖类产生乙醇和二氧化碳。

3. The Fermenter: Design and Conditions | 发酵罐：设计与条件

Industrial fermenters are large vessels designed to grow microorganisms in controlled conditions. They are typically made of stainless steel, with a water jacket for temperature control, a stirrer to keep the mixture well-mixed, and probes to monitor pH, temperature, and oxygen levels. Sterile conditions are essential to prevent contamination by unwanted microbes.

工业发酵罐是设计用于在受控条件下培养微生物的大型容器。它们通常由不锈钢制成，带有夹套用于温度控制、搅拌器以保持混合均匀，以及监测 pH、温度和氧气水平的探头。无菌条件对于防止不受欢迎的微生物污染至关重要。

Key conditions maintained in a fermenter include: a suitable temperature (often around 30-40 °C for yeast, 25-28 °C for penicillin production), an appropriate pH, and an adequate supply of nutrients and oxygen (if aerobic). The paddle stirrer helps distribute heat and oxygen evenly. Aseptic techniques, such as sterilising the fermenter with steam, are used before inoculation.

发酵罐中维持的关键条件包括：合适的温度（酵母常约 30-40 °C，青霉素生产 25-28 °C）、适当的 pH，以及充足的营养和氧气供应（如需氧）。搅拌桨有助于均匀分布热量和氧气。无菌技术，例如用蒸汽灭菌发酵罐，在接种前使用。

4. Production of Bread | 面包的生产

Bread making is a classic example of biotechnology using yeast. Yeast is mixed with flour, water, sugar, and salt to form dough. The yeast ferments the sugars, producing carbon dioxide bubbles that become trapped in the gluten network of the dough, causing it to rise. When the dough is baked, the high temperature kills the yeast, evaporates the alcohol produced, and sets the structure.

面包制作是利用酵母进行生物技术的经典例子。酵母与面粉、水、糖和盐混合形成面团。酵母发酵糖类，产生的二氧化碳气泡被困在面团的麸质网络中，使面团膨胀。当面团烘烤时，高温杀死酵母，蒸发掉产生的酒精，并使结构定型。

The sugar used by yeast comes from the breakdown of starch in flour by enzymes called amylases. The longer the dough is left to rise (proving), the more carbon dioxide is produced, resulting in a lighter, airier loaf. The ethanol produced is driven off during baking, so no alcohol remains in the bread.

酵母使用的糖来自面粉中淀粉被淀粉酶分解的产物。面团醒发的时间越长，产生的二氧化碳越多，面包就越轻盈多孔。产生的乙醇在烘烤过程中挥发掉，因此面包中不残留酒精。

5. Production of Yoghurt | 酸奶的生产

Yoghurt is made by fermenting milk with bacteria, mainly Lactobacillus bulgaricus and Streptococcus thermophilus. First, milk is pasteurised (heated to about 85-95 °C) to kill any harmful bacteria, then cooled to about 40-46 °C. The bacteria culture is added, and the mixture is incubated for several hours.

酸奶是通过用细菌（主要是保加利亚乳杆菌和嗜热链球菌）发酵牛奶制成的。首先，牛奶经过巴氏消毒（加热至约 85-95 °C）以杀死任何有害细菌，然后冷却至约 40-46 °C。加入菌种，混合物保温培养数小时。

The bacteria convert lactose (milk sugar) into lactic acid. The lactic acid lowers the pH, causing the milk proteins (casein) to coagulate and form a semi-solid gel — the characteristic texture of yoghurt. Additionally, the acidic environment prevents the growth of spoilage microorganisms, extending shelf life. Flavours and fruits can be added afterwards.

细菌将乳糖转化为乳酸。乳酸降低 pH，使牛奶蛋白（酪蛋白）凝结并形成半固态凝胶——酸奶特有的质地。此外，酸性环境阻止腐败微生物的生长，延长了保质期。之后可添加调味剂和水果。

6. Production of Penicillin and Other Antibiotics | 青霉素及其他抗生素的生产

Penicillin is a secondary metabolite produced by the fungus Penicillium chrysogenum. In industrial production, the fungus is grown in a fermenter under sterile, aerobic conditions. The medium contains nutrients such as corn steep liquor and lactose. Growth occurs in two phases: first, the trophophase, where the fungus grows rapidly; then the idiophase, when the fungus begins to secrete penicillin.

青霉素是产黄青霉产生的次生代谢产物。在工业生产中，该真菌在无菌、有氧条件下的发酵罐中培养。培养基含有玉米浆和乳糖等营养物质。生长分两个阶段：首先营养期，真菌快速生长；然后生产期，真菌开始分泌青霉素。

Temperature is kept around 25-28 °C, pH about 6.5, and oxygen is continuously supplied. The fermenter is stirred gently because the fungus forms filamentous (hyphal) clumps that are sensitive to shear forces. After fermentation, the penicillin is extracted and purified. This batch process has revolutionised medicine by providing a reliable supply of antibiotics.

温度保持在 25-28 °C 左右，pH 约 6.5，并持续供应氧气。发酵罐需轻柔搅拌，因为真菌形成丝状菌团，对剪切力敏感。发酵结束后，提取和纯化青霉素。这种分批生产过程通过提供可靠的抗生素供应彻底改变了医学。

7. Genetic Modification (GM) in Biotechnology | 生物技术中的基因改造

Modern biotechnology often involves genetic engineering — transferring genes from one organism to another. This is used to produce human insulin, growth hormones, and GM crops with desirable traits such as herbicide resistance or increased nutritional value. The basic steps include isolating the desired gene, inserting it into a vector (e.g., plasmid), and introducing it into the host cell.

现代生物技术通常涉及基因工程——将基因从一个生物体转移到另一个。这用于生产人胰岛素、生长激素，以及具有抗除草剂或增加营养价值等优良性状的转基因作物。基本步骤包括分离目的基因、将其插入载体（如质粒）、再导入宿主细胞。

For example, the human insulin gene is cut out using restriction enzymes, spliced into a bacterial plasmid using ligase, and then inserted into E. coli bacteria. The transgenic bacteria multiply in a fermenter, producing large quantities of human insulin, which is harvested and purified. This method provides an ethical and efficient alternative to animal insulin.

例如，人胰岛素基因用限制酶切出，用连接酶拼接到细菌质粒中，然后导入大肠杆菌。转基因细菌在发酵罐中大量繁殖，生产大量人胰岛素，收获并纯化。这种方法提供了动物胰岛素的伦理和高效替代品。

8. Use of Enzymes in Industry | 工业中酶的应用

Enzymes are biological catalysts that speed up reactions without being used up. In biotechnology, isolated enzymes are used in various industries. For example, proteases and lipases are added to biological washing powders to break down protein and fat stains at lower temperatures, saving energy. Amylases are used to break down starch in the production of glucose syrup.

酶是生物催化剂，能加速反应而本身不被消耗。在生物技术中，分离出的酶被用于各种工业。例如，蛋白酶和脂肪酶添加到生物洗衣粉中，可在较低温度下分解蛋白质和脂肪污渍，节约能源。淀粉酶用于分解淀粉以生产葡萄糖浆。

In fruit juice production, pectinase breaks down pectin, increasing juice yield and clarity. In cheese making, chymosin (a protease) coagulates milk proteins. Enzymes from microorganisms are often preferred because they can be produced in large quantities, are quickly secreted, and can withstand harsher conditions than plant or animal enzymes.

在果汁生产中，果胶酶分解果胶，提高出汁率和澄清度。在奶酪制作中，凝乳酶（一种蛋白酶）使牛奶蛋白凝结。微生物来源的酶通常更受青睐，因为它们可大量生产、分泌迅速，且比动植物酶更能耐受苛刻条件。

9. Biofuels and Biogas | 生物燃料与沼气

Biofuels are fuels produced from biological material (biomass). Ethanol can be produced by yeast fermentation of sugars from crops like sugarcane or maize, and then used as a fuel or blended with petrol. Biogas, mainly methane, is produced by anaerobic digestion of organic waste such as manure or crop residues by bacteria.

生物燃料是从生物材料（生物质）生产的燃料。乙醇可以通过酵母发酵甘蔗或玉米等作物中的糖来生产，然后用作燃料或与汽油混合使用。沼气主要是甲烷，由细菌对粪便或作物残余等有机废物进行厌氧消化产生。

A simple biogas generator (digester) consists of a sealed container in which organic waste is decomposed by methanogenic bacteria. The methane gas is collected and can be burned for cooking, heating, or generating electricity. The leftover slurry is a nutrient-rich fertiliser. Using biofuels reduces dependence on fossil fuels and can be carbon-neutral.

简单的沼气发生器（消化器）由一个密封容器组成，产甲烷细菌在其中分解有机废物。收集的甲烷气体可燃烧用于烹饪、取暖或发电。残留下来的沼渣是富含营养的肥料。使用生物燃料减少了对化石燃料的依赖，并可能是碳中和的。

10. Bioremediation and Environmental Biotechnology | 生物修复与环境生物技术

Bioremediation is the use of microorganisms to clean up environmental pollutants. Certain bacteria can break down oil spills (hydrocarbons), pesticides, or heavy metals into less harmful substances. This is a natural, cost-effective way to restore contaminated habitats. Phytoremediation uses plants to absorb and accumulate pollutants from soil or water.

生物修复是利用微生物清理环境污染物的过程。某些细菌可以分解石油泄漏物（碳氢化合物）、农药或重金属，将其转化为危害较小的物质。这是一种恢复受污染栖息地的自然且经济有效的方法。植物修复利用植物从土壤或水中吸收和积累污染物。

For instance, after an oil tanker spill, nitrogen and phosphorus fertilisers may be added to stimulate the growth of naturally occurring oil-degrading bacteria. In sewage treatment, microorganisms break down organic matter in aerated tanks, reducing biological oxygen demand (BOD) before the water is released into rivers.

例如，油轮泄漏后，可添加氮磷肥料以刺激天然存在的石油降解细菌的生长。在污水处理中，微生物在曝气池中分解有机物，降低生物需氧量，然后水才排入河流。

11. Ethical and Safety Considerations | 伦理与安全考量

The use of biotechnology raises several ethical questions. Genetically modified organisms (GMOs) may pose risks to ecosystems if they crossbreed with wild relatives. Some people object to GM foods on principle, citing unknown long-term health effects. The use of animals in genetic engineering (e.g., pharming) is also controversial.

生物技术的使用引发了一些伦理问题。转基因生物如果与野生近缘种杂交，可能对生态系统构成风险。一些人原则上反对转基因食品，理由是未知的长期健康影响。在基因工程中使用动物（如转基因动物制药）也颇具争议。

Safety measures in biotechnological industries are strictly regulated. Fermenters are designed for containment to prevent the escape of genetically modified microorganisms. Products such as insulin are extensively purified and tested to ensure they are free from harmful compounds. Continuous monitoring and risk assessments are mandatory.

生物技术行业的安全措施受到严格监管。发酵罐设计有防护措施，防止转基因微生物逃逸。胰岛素等产品经过广泛纯化和检测，确保不含任何有害化合物。持续监控和风险评估是强制性的。

12. Exam Tips and Common Pitfalls | 考试技巧与常见错误

When answering exam questions on biotechnology, always read the context carefully. If the question asks for ‘aerobic’ conditions, do not discuss ethanol production. Use precise terminology: ‘fermenter’ not ‘container’, ‘inoculate’ not ‘add bacteria’, and distinguish between ‘pasteurisation’ and ‘sterilisation’. Marks are often given for explaining how a particular condition (e.g., temperature, pH) affects enzyme activity.

回答生物技术考试问题时，一定要仔细阅读语境。如果问题要求“有氧”条件，不要讨论乙醇生产。使用精确术语：“发酵罐”而非“容器”，“接种”而非“添加细菌”，并区分“巴氏消毒”和“灭菌”。解释特定条件（如温度、pH）如何影响酶活性通常可得满分。

Common mistakes include confusing the roles of yeast in bread (CO₂ for rising) and beer (ethanol), forgetting the need for sterile conditions in penicillin production, and describing biogas as mainly ethanol rather than methane. Practice drawing and labelling a fermenter diagram with aseptic features. Also, be prepared to evaluate the advantages and disadvantages of GM organisms.

常见错误包括混淆酵母在面包（CO₂用于膨胀）和啤酒（乙醇）中的作用，忘记青霉素生产需要无菌条件，以及将沼气描述为主要是乙醇而非甲烷。练习绘制并标注带有无菌特征的发酵罐示意图。同时，准备好评估转基因生物的利弊。

For higher marks, consider the wider implications: how biotechnology can help us achieve sustainable development goals, such as reducing fossil fuel use, improving food security, and cleaning up polluted environments. Use specific examples from the course wherever possible.

为了获得更高分，要考虑更广泛的影响：生物技术如何帮助我们实现可持续发展目标，例如减少化石燃料使用、提高粮食安全和清理污染环境。尽可能使用课程中的具体例子。

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IGCSE OCR Biology: Biotechnology Revision | IGCSE OCR 生物：生物技术 考点精讲