GCSE CIE Biology: Biotechnology Revision Notes | GCSE CIE 生物：生物技术考点精讲

📚 GCSE CIE Biology: Biotechnology Revision Notes | GCSE CIE 生物：生物技术考点精讲

Biotechnology is the application of living organisms, biological systems, or their derivatives to develop or create useful products. In the CIE IGCSE Biology syllabus, biotechnology topics focus on fermentation, the use of microorganisms in food production, genetic modification, and the ethical considerations surrounding these technologies. This article provides a comprehensive yet concise summary of the key learning points, helping you master the core concepts and excel in your exam.

生物技术是利用生物体、生物系统或其衍生物来开发或创造有用产品的应用学科。在 CIE IGCSE 生物课程大纲中，生物技术专题主要涵盖发酵、微生物在食品生产中的应用、基因改造以及与这些技术相关的伦理考量。本文提供全面而简明的考点总结，帮助你掌握核心概念，在考试中取得优异成绩。

1. What Is Biotechnology? | 什么是生物技术？

Biotechnology refers to the use of living organisms (especially microorganisms) and biological processes to manufacture products or solve problems. It is not a new field—traditional biotechnologies like bread making and brewing have been practised for thousands of years. Modern biotechnology, however, often involves genetic engineering and the large-scale industrial use of enzymes.

生物技术是指利用生物体（尤其是微生物）和生物过程来制造产品或解决问题。这并非一个新兴领域——像制作面包和酿造啤酒这样的传统生物技术已经实践了数千年。然而，现代生物技术通常涉及基因工程和酶的规模化工业应用。

A key feature of biotechnological processes is that they use enzymes, either within cells (e.g., yeast performing fermentation) or isolated and purified for specific reactions. These reactions typically occur under mild conditions—moderate temperatures, normal atmospheric pressure, and neutral pH—making them more sustainable and energy-efficient compared to many chemical processes.

生物技术过程的一个关键特征是利用酶，这些酶可以在细胞内部发挥作用（例如酵母进行发酵），也可以被分离纯化用于特定反应。这些反应通常在温和条件下进行——适中的温度、常压和中性 pH，这使得它们比许多化学过程更具可持续性和能效。

2. Microorganisms in Biotechnology | 生物技术中的微生物

Microorganisms such as bacteria and fungi are the workhorses of biotechnology. They are used because they are cheap to grow, reproduce rapidly, and can produce a vast array of products. The choice of microorganism depends on the desired product and the required growth conditions. For example, the bacterium Lactobacillus is used in yoghurt production, while the fungus Penicillium produces the antibiotic penicillin.

细菌和真菌等微生物是生物技术的主力军。它们之所以被采用，是因为培养成本低、繁殖迅速，并且能够生产多种多样的产物。微生物的选择取决于目标产物和所需的生长条件。例如，乳酸菌用于酸奶生产，而青霉菌则产生抗生素青霉素。

In industrial settings, microorganisms are often cultured in large vessels called fermenters. The conditions inside a fermenter—temperature, pH, oxygen supply, and nutrient availability—are carefully controlled to maximise yield. Sterile conditions are essential to prevent contamination by other microorganisms that could outcompete the production strain or spoil the product.

在工业环境中，微生物通常是在称为发酵罐的大型容器中培养的。发酵罐内的条件——温度、pH、氧气供应和营养物质的可获得性——被精确控制以最大化产量。无菌条件至关重要，可防止其他微生物污染，这些杂菌可能会胜过生产菌株或破坏产品。

3. Fermentation and Its Products | 发酵及其产物

Fermentation is a metabolic process in which microorganisms break down organic compounds, often in the absence of oxygen (anaerobic respiration). In CIE Biology, the focus is on ethanol fermentation by yeast and lactic acid fermentation by bacteria.

发酵是微生物分解有机化合物的代谢过程，通常在无氧条件下（厌氧呼吸）进行。在 CIE 生物学中，重点在于酵母的乙醇发酵和细菌的乳酸发酵。

Yeast (Saccharomyces cerevisiae) carries out anaerobic respiration to produce ethanol and carbon dioxide from glucose. The word equation is:

酵母（酿酒酵母）进行厌氧呼吸，将葡萄糖转化为乙醇和二氧化碳。文字方程式为：

Glucose → Ethanol + Carbon Dioxide

葡萄糖 → 乙醇 + 二氧化碳

This reaction is exploited in bread making, where the carbon dioxide makes dough rise, and in brewing and winemaking, where ethanol is the desired product. In bread, the ethanol evaporates during baking.

该反应被用于面包制作（二氧化碳使面团膨胀）和酿酒（乙醇为目标产物）。在面包中，乙醇在烘烤过程中蒸发。

Lactic acid fermentation is carried out by certain bacteria, such as Lactobacillus, used in yoghurt making. The bacteria convert lactose (milk sugar) into lactic acid. The acid lowers the pH, causing milk proteins to coagulate and thicken the milk, giving yoghurt its texture and tangy taste. The equation is:

乳酸发酵由某些细菌（如用于酸奶制作的乳酸菌）进行。细菌将乳糖（奶中的糖）转化为乳酸。乳酸降低 pH，使奶中的蛋白质凝固变稠，赋予酸奶特有的质感和酸味。方程式为：

Lactose → Lactic Acid

乳糖 → 乳酸

4. Uses of Enzymes in Biotechnology | 酶在生物技术中的应用

Besides whole-cell fermentation, isolated enzymes are used in many industrial processes. Enzymes are biological catalysts that speed up reactions without being used up. They are specific, meaning each enzyme works on a particular substrate, and they function best under specific temperature and pH conditions.

除了全细胞发酵，分离提纯的酶也被用于许多工业过程。酶是生物催化剂，能加快反应速度而自身不被消耗。酶具有专一性，即每种酶作用于特定的底物，并在特定温度和 pH 条件下发挥最佳活性。

Common examples include pectinase for fruit juice extraction (breaks down pectin in cell walls to release more juice and improve clarity), proteases in biological detergents (remove protein-based stains like blood and food), and lactase to produce lactose-free milk. Lactase converts lactose into glucose and galactose, making milk digestible for lactose-intolerant individuals.

常见的例子包括用于果汁提取的果胶酶（分解细胞壁中的果胶，释放更多果汁并提高澄清度）、生物洗涤剂中的蛋白酶（去除血渍和食物等蛋白质类污渍），以及用于生产无乳糖牛奶的乳糖酶。乳糖酶将乳糖转化为葡萄糖和半乳糖，使乳糖不耐受人群能够消化牛奶。

In the exam, you may be asked to explain the advantages of using isolated enzymes over whole cells. These advantages include: greater specificity (no side reactions), the ability to function under harsher conditions if the enzyme is thermostable, easier downstream purification of the product, and the possibility to reuse the enzyme if immobilised.

在考试中，你可能会被要求解释使用分离酶相较于全细胞的优势。这些优势包括：更高的专一性（无副反应），若酶具有热稳定性则可在更严苛的条件下发挥作用，产物更容易的下游纯化，以及如果固定化，酶可以重复使用。

5. Yoghurt Production | 酸奶生产

Yoghurt making is a classic CIE practical investigation topic. The process involves two species of bacteria: Lactobacillus bulgaricus and Streptococcus thermophilus. The steps are straightforward:

酸奶制作是 CIE 课程中一个经典的实践探究课题。该过程涉及两种细菌：保加利亚乳杆菌和嗜热链球菌。操作步骤如下：

Milk is first pasteurised (heated to about 72°C for 15 seconds) to kill any harmful microorganisms.

首先对牛奶进行巴氏消毒（加热至约 72℃，持续 15 秒），以杀灭所有有害微生物。
The milk is then cooled to around 40–45°C, a temperature suitable for the bacterial cultures.

然后将牛奶冷却至约 40–45℃，该温度适合细菌培养物生长。
A starter culture of the bacteria is added, and the mixture is incubated at this temperature for several hours. The bacteria ferment lactose into lactic acid. The acid causes milk protein (casein) to coagulate, forming a semi-solid gel.

加入含有上述细菌的发酵剂，在此温度下保温数小时。细菌将乳糖发酵成乳酸。乳酸使牛奶蛋白质（酪蛋白）凝固，形成半固体凝胶。
Once the desired consistency and acidity are reached, the yoghurt is cooled to stop the fermentation process.

达到理想的稠度和酸度后，将酸奶冷却以停止发酵过程。

The entire equipment and the milk must be kept sterile until the starter culture is added, otherwise unwanted microorganisms may produce toxins or spoil the yoghurt.

在加入发酵剂之前，所有设备和牛奶必须保持无菌状态，否则有害微生物可能产生毒素或导致酸奶变质。

6. Industrial Fermenter Design | 工业发酵罐设计

A large-scale fermenter (or bioreactor) is designed to provide the optimum conditions for microbial growth and product formation. The diagram of a fermenter and its functions are a firm favourite in the examination. Key features include:

大规模发酵罐（生物反应器）的设计旨在为微生物生长和产物形成提供最适条件。发酵罐示意图及其功能是考试中的热门考点。关键特征包括：

Feature 特征	Function 功能
Stirrer / Impeller 搅拌器/叶轮	Keeps the contents well mixed, ensuring even distribution of nutrients, temperature, and oxygen.
Water Jacket 水夹套	Circulates water at a controlled temperature to maintain optimum growth temperature and to cool the fermenter when the microorganisms respire and generate heat.
Air Inlet / Sparger 空气入口/分布器	Supplies sterile air for aerobic fermentation; the sparger breaks the air into tiny bubbles to increase surface area for oxygen dissolution.
pH Probe pH 探头	Monitors pH; acid or alkali can be added as needed to maintain the optimal pH for enzyme activity.
Temperature Probe 温度探头	Constantly monitors temperature to ensure it stays within the designated range.
Outlet Tap 出口阀	Allows collection of the final product without contaminating the interior.
Aseptic Seals 无菌密封	Prevents entry of unwanted microorganisms and maintains a sterile environment.

You must be able to explain why aseptic conditions are so important: to prevent contamination that could reduce yield by competing for nutrients, produce toxic by-products, or completely ruin the batch.

你必须能够解释无菌条件为何如此重要：为了防止污染，污染会通过竞争营养物质降低产量、产生有毒副产品或彻底毁掉整批产品。

7. Genetic Engineering (Genetic Modification) | 基因工程（基因改造）

Genetic engineering is a modern biotechnology technique that alters the genetic material of an organism to give it a desired characteristic. The CIE syllabus covers the basic process, the use of bacterial cells, and specific examples like the production of human insulin.

基因工程是一种现代生物技术，通过改变生物体的遗传物质赋予其理想性状。CIE 课程大纲涵盖基本过程、细菌细胞的使用以及生产人胰岛素等具体实例。

The main steps include:

主要步骤包括：

Identification and isolation of the desired gene (e.g., using restriction enzymes that cut DNA at specific sequences).

识别并分离所需基因（例如，使用能在特定序列处切割 DNA 的限制性内切酶）。
Insertion of the gene into a vector, typically a plasmid (a small circular DNA molecule from bacteria). The plasmid is cut with the same restriction enzyme, so the sticky ends are complementary.

将基因插入载体，载体通常是质粒（来自细菌的小型环状 DNA 分子）。质粒用相同的限制酶切割，因此黏性末端可以互补配对。
The vector is transferred into a host cell (often a bacterium such as E. coli). The host cell now contains the recombinant DNA and is known as a genetically modified (GM) organism.

将载体转入宿主细胞（通常是大肠杆菌等细菌）。宿主细胞现在含有重组 DNA，称为转基因生物（GM 生物）。
The host cell multiplies, each copy carrying the recombinant DNA. The desired gene is expressed, and the host produces the required protein (e.g., insulin).

宿主细胞繁殖，每个拷贝都携带重组 DNA。所需基因表达，宿主产生目标蛋白质（如胰岛素）。

The production of human insulin by genetically engineered bacteria is a landmark achievement. Previously, diabetics relied on insulin extracted from pigs or cows, which could cause immune reactions. Human insulin produced in bacteria is identical to our own, pure, and can be produced in large quantities relatively cheaply.

利用基因工程细菌生产人胰岛素是一项里程碑式的成就。过去，糖尿病患者依赖从猪或牛提取的胰岛素，可能引起免疫反应。转基因细菌生产的人胰岛素与我们自身的胰岛素完全相同，纯度高，且可以相对廉价地大量生产。

8. Crop Genetic Modification | 作物基因改造

GM technology is also applied to crop plants to introduce traits such as resistance to herbicides or insect pests, improved nutritional content, or tolerance to environmental stress. A common example is the insertion of a gene from the bacterium Bacillus thuringiensis (Bt) into maize or cotton; the plants then produce a protein that is toxic to specific insect larvae but harmless to humans.

GM 技术也应用于作物，以引入诸如抗除草剂或抗害虫、改善营养成分、或耐受环境胁迫等性状。一个常见的例子是将苏云金芽孢杆菌（Bt）的一个基因插入玉米或棉花中；植物随后产生一种对特定昆虫幼虫有毒但对人类无害的蛋白质。

In the exam, you need to discuss the advantages and disadvantages of GM crops. Potential advantages include: higher yields, reduced need for chemical pesticides (lowering cost and environmental impact), the ability to grow crops in otherwise unsuitable environments (e.g., drought-resistant varieties), and enhancing nutritional value (e.g., Golden Rice with added beta-carotene).

在考试中，你需要讨论 GM 作物的优点和缺点。优点包括：更高的产量、减少化学农药需求（降低成本及环境影响）、能够在原本不适宜的环境中种植作物（如抗旱品种），以及提高营养价值（例如添加了β-胡萝卜素的“黄金大米”）。

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

Biotechnology, especially genetic modification, raises ethical questions. You must be able to articulate balanced arguments. Concerns include:

生物技术，尤其是基因改造，引发了伦理问题。你必须能够阐述平衡的观点。担忧包括：

Possible transfer of antibiotic resistance genes from GM bacteria to pathogens, making diseases harder to treat.

转基因细菌的抗生素抗性基因可能转移到病原体中，使疾病更难治疗。
Risk of GM pollen spreading to wild plants, creating ‘superweeds’ or reducing biodiversity.

转基因花粉可能传播到野生植物中，产生“超级杂草”或降低生物多样性。
Long-term health effects of consuming GM foods are not fully known, though most scientific bodies consider approved GM foods safe.

尽管大多数科学机构认为经批准的转基因食品是安全的，但长期食用转基因食品的健康影响尚未完全明确。
Ethical objection to ‘playing God’ or the patenting of life forms, which may disadvantage small farmers.

对“扮演上帝角色”或生命形式专利化的伦理反对，这可能损害小农的利益。

Strict regulations and monitoring are in place in many countries. For the CIE exam, focus on explaining that the decision-making process involves a risk–benefit analysis, considering evidence and weighing potential benefits against potential risks.

许多国家实行严格的监管和监控。在 CIE 考试中，重点解释决策过程涉及风险-收益分析，要考量证据，权衡潜在益处与潜在风险。

10. Immobilised Enzymes | 固定化酶

Enzymes can be immobilised (attached to an inert material) to enhance their industrial utility. Common methods include encapsulation in alginate beads, adsorption onto a surface, or covalent bonding to a support. The CIE syllabus often uses lactase immobilised in alginate beads to produce lactose-free milk as a model system.

酶可以被固定化（附着于惰性材料上）以增强其工业实用性。常见方法包括包裹在藻酸盐珠中、吸附在表面上，或通过共价键连接到载体上。CIE 课程大纲常以藻酸盐珠固定化乳糖酶生产无乳糖牛奶作为模型系统。

Advantages of immobilised enzymes include:

固定化酶的优势包括：

Enzyme can be recovered and reused, reducing costs.

酶可以回收并重复使用，降低成本。
Product is not contaminated with enzyme, so downstream purification is simpler.

产物不会被酶污染，因此下游纯化更简单。
Immobilisation often increases enzyme stability to changes in temperature and pH.

固定化通常能增强酶对温度和 pH 变化的稳定性。
Process can be run continuously (e.g., in a column), which is more efficient for large-scale production.

过程可连续进行（例如在层析柱中），这对于大规模生产更高效。

11. Exam Tips for Biotechnology | 生物技术考试技巧

In the CIE Biology exam, biotech questions frequently appear in both Paper 2 (multiple choice) and Paper 4 (theory). Ensure you can:

在 CIE 生物考试中，生物技术试题经常出现在 Paper 2（选择题）和 Paper 4（理论）中。确保你能做到：

Write word equations for ethanol fermentation and lactic acid fermentation.

写出乙醇发酵和乳酸发酵的文字方程式。
Label and explain the functions of a fermenter’s components.

标注并解释发酵罐各部件的功能。
Describe the steps of genetic engineering using the correct terms (restriction enzyme, vector, plasmid, host cell, recombinant DNA).

使用正确术语描述基因工程的步骤（限制酶、载体、质粒、宿主细胞、重组 DNA）。
Discuss advantages and disadvantages of GM crops, providing a balanced view.

讨论 GM 作物的优点和缺点，提供平衡的观点。
Explain the use of immobilised enzymes with a practical example.

用实际例子解释固定化酶的应用。
Always mention the need for aseptic technique when culturing microorganisms.

在培养微生物时，始终提及无菌技术的必要性。

Practice graph interpretation as well: you might be given data on product formation over time or under different conditions, and asked to deduce the optimum pH or temperature for a biotech process.

还要练习图表解读：你可能会遇到关于产物形成随时间变化或在不同条件下的数据，并被要求推断某生物技术过程的最适 pH 或温度。

12. Summary Table of Key Biotech Processes | 关键生物技术过程汇总表

The table below summarises the core processes you are expected to know:

下表总结了你需要掌握的核心过程：

Product 产物	Microorganism or Enzyme 微生物或酶	Substrate 底物	Key Points 要点
Yoghurt 酸奶	Lactobacillus, Streptococcus thermophilus	Lactose in milk 乳糖	Lactic acid coagulates milk; sterile conditions needed.
Bread 面包	Yeast (Saccharomyces cerevisiae)	Carbohydrate in flour 面粉中的碳水化合物	CO₂ causes dough to rise; ethanol evaporates.
Beer / Wine 啤酒/葡萄酒	Yeast	Sugars in barley/grapes 大麦/葡萄中的糖	Anaerobic conditions; ethanol is the desired product.
Lactose-free milk 无乳糖牛奶	Lactase (often immobilised)	Lactose	Lactose → glucose + galactose; used to treat lactose intolerance.
Human insulin 人胰岛素	GM E. coli	Nutrients in fermenter	Gene for insulin inserted into a plasmid; bacteria produce insulin identical to human.
Biological detergents 生物洗涤剂	Protease, lipase	Protein, fat stains	Enzymes break down macromolecules; work best at moderate temperatures.

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GCSE CIE Biology: Biotechnology Revision Notes | GCSE CIE 生物：生物技术 考点精讲