GCSE WJEC Biology: Cell Organelles Exam Essentials | GCSE WJEC 生物：细胞器 考点精讲

📚 GCSE WJEC Biology: Cell Organelles Exam Essentials | GCSE WJEC 生物：细胞器 考点精讲

Cell organelles are the tiny structures inside cells that perform specific functions, much like organs in the human body. In GCSE WJEC Biology, you must be able to identify organelles on diagrams, describe their roles, and compare their presence in animal, plant and bacterial cells. Mastering this topic will help you answer questions on cell structure, levels of organisation, and specialised cells with confidence.

细胞器是细胞内执行特定功能的微小结构，就像人体的器官一样。在 GCSE WJEC 生物考试中，你必须能在图上辨识细胞器、描述其作用，并比较它们在动物、植物和细菌细胞中的分布。掌握这一主题将帮助你有信心地回答关于细胞结构、组织层次和特化细胞的问题。

1. What Are Organelles? | 什么是细胞器？

Organelle means ‘little organ’. Each organelle is a membrane-bound or non-membrane-bound compartment within a cell that carries out a specialised job. The main organelles studied at GCSE include the nucleus, cytoplasm, cell membrane, mitochondria, ribosomes, chloroplasts, permanent vacuole and cell wall. All cells have cytoplasm, cell membrane and ribosomes, but other organelles vary depending on the type of cell.

细胞器（organelle）意为“小器官”。每个细胞器都是细胞内一个具膜或不具膜的分区，执行专门的工作。GCSE 阶段学习的主要细胞器包括细胞核、细胞质、细胞膜、线粒体、核糖体、叶绿体、中央大液泡和细胞壁。所有细胞都有细胞质、细胞膜和核糖体，但其他细胞器因细胞类型而异。

2. Nucleus – The Control Centre | 细胞核——控制中心

The nucleus is a large, spherical organelle surrounded by a double membrane called the nuclear envelope. It contains the cell’s genetic material in the form of DNA arranged into chromosomes. The nucleus controls all cellular activities by regulating gene expression. In a diagram, it often stains darker than the surrounding cytoplasm. Most animal and plant cells have a nucleus, but red blood cells lose theirs during maturation, and bacterial cells never have a true nucleus.

细胞核是一个大的球状细胞器，由称为核膜的双层膜包围。它含有细胞的遗传物质，即排列成染色体的 DNA。细胞核通过调控基因表达来控制所有细胞活动。在图中，细胞核通常比周围的细胞质染色更深。大多数动物和植物细胞有细胞核，但红细胞在成熟过程中会失去细胞核，而细菌细胞从未有真正的细胞核。

3. Cytoplasm and Cell Membrane – Life’s Solutions and Gatekeeper | 细胞质和细胞膜——生命溶液与守门员

Cytoplasm is a jelly-like fluid composed mainly of water, salts and enzymes, filling the space between the cell membrane and the nucleus. Many metabolic reactions, including parts of respiration and protein synthesis, occur here. The cell membrane, or plasma membrane, is a thin, partially permeable barrier made of phospholipids and proteins. It controls which substances enter and leave the cell, allowing small molecules like oxygen and water to pass while blocking larger or charged particles. Both cytoplasm and cell membrane are found in all living cells.

细胞质是一种胶状液体，主要由水、盐和酶组成，填充细胞膜与细胞核之间的空间。许多代谢反应，包括部分呼吸作用和蛋白质合成，都在此发生。细胞膜（也称质膜）是一层薄薄的、选择性渗透的屏障，由磷脂和蛋白质构成。它控制哪些物质进出细胞，允许像氧气和水这样的小分子通过，而阻挡较大或带电粒子。细胞质和细胞膜在所有活细胞中都存在。

4. Mitochondria – Powerhouses of the Cell | 线粒体——细胞的能量工厂

Mitochondria are rod-shaped organelles with a double membrane; the inner membrane is folded into structures called cristae, which increase surface area for respiratory enzymes. Here, aerobic respiration takes place to release energy from glucose in the form of ATP. Cells with high energy demands, such as muscle cells and sperm cells, contain many mitochondria. Mitochondria are found in almost all eukaryotic cells, but they are absent from bacterial cells, which carry out respiration on their cell membrane instead.

线粒体是杆状细胞器，具有双层膜；内膜折叠成称为嵴（cristae）的结构，增加了呼吸酶的表面积。在这里，有氧呼吸作用将葡萄糖中的能量以 ATP 形式释放出来。能量需求高的细胞，如肌细胞和精子细胞，含有大量线粒体。线粒体几乎存在于所有真核细胞中，但细菌细胞中没有；细菌在细胞膜上进行呼吸作用。

5. Ribosomes – Tiny Protein Factories | 核糖体——微小的蛋白质工厂

Ribosomes are extremely small organelles, not surrounded by a membrane. They can float freely in the cytoplasm or be attached to the rough endoplasmic reticulum (not required in detail at GCSE). Ribosomes are the site of protein synthesis, where amino acids are linked together according to the instructions carried by mRNA from the nucleus. Both eukaryotic and prokaryotic cells possess ribosomes, making them a universal feature of life. However, bacterial ribosomes are slightly smaller (70S vs 80S).

核糖体是非常小的细胞器，没有膜包裹。它们可以自由漂浮在细胞质中，或附着在粗面内质网上（GCSE 不需详细掌握）。核糖体是蛋白质合成的场所，氨基酸依照来自细胞核的 mRNA 指令在此连接成链。真核和原核细胞都有核糖体，这使得它们成为生命的普遍特征。不过，细菌的核糖体略小（70S 与 80S）。

6. Chloroplasts – Solar-Powered Kitchens | 叶绿体——太阳能厨房

Chloroplasts are large, green organelles found only in plant cells and some algae. They are bounded by a double membrane and contain stacks of disc-like structures called grana, where chlorophyll is found. Chlorophyll absorbs light energy to carry out photosynthesis, converting carbon dioxide and water into glucose and oxygen. Chloroplasts are absent in animal and fungal cells. In root cells, chloroplasts are usually absent because roots do not perform photosynthesis.

叶绿体是大的绿色细胞器，仅存在于植物细胞和一些藻类中。它们由双层膜包被，内含称做基粒（grana）的碟状结构堆栈，叶绿素便位于其中。叶绿素吸收光能进行光合作用，将二氧化碳和水转化为葡萄糖和氧气。动物和真菌细胞没有叶绿体。根细胞中通常也不含叶绿体，因为根部不进行光合作用。

7. Permanent Vacuole – Storage and Support | 中央大液泡——储存与支撑

The permanent vacuole is a large, fluid-filled sac surrounded by a membrane called the tonoplast. It occupies up to 90% of the volume in mature plant cells. The vacuole contains cell sap – a solution of water, sugars, salts and pigments. It maintains turgor pressure against the cell wall, keeping the plant upright and firm. Animal cells may contain small, temporary vacuoles, but they do not have a large, permanent one.

中央大液泡是一个充满液体的大囊，由称为液泡膜（tonoplast）的膜包裹。在成熟的植物细胞中，它可占据多达 90% 的体积。液泡内含细胞液——一种水、糖、盐和色素的溶液。它维持对细胞壁的膨压，使植物保持挺拔和坚挺。动物细胞可能含有小而临时的液泡，但没有大的、永久的中央液泡。

8. Cell Wall – The Protective Exoskeleton | 细胞壁——保护性外骨骼

The cell wall is a rigid layer outside the cell membrane. In plants, it is made of cellulose, which is strong and provides structural support. The cell wall is fully permeable, allowing water and dissolved substances to pass through freely. In bacteria, the cell wall is made of peptidoglycan (murein) instead of cellulose. Fungal cell walls are made of chitin. The presence of a cell wall distinguishes plant, bacterial and fungal cells from animal cells, which lack any cell wall.

细胞壁是位于细胞膜外的一层刚性结构。在植物中，细胞壁由纤维素构成，纤维素质地坚固，提供结构支撑。细胞壁是全透性的，允许水和溶解物质自由通过。在细菌中，细胞壁由肽聚糖（胞壁质）构成，而非纤维素。真菌细胞壁则由几丁质构成。细胞壁的存在将植物、细菌和真菌细胞与没有细胞壁的动物细胞区分开来。

9. Bacterial Cell Organelles – Simpler but Efficient | 细菌细胞器——更简单但高效

Bacterial cells are prokaryotic and much smaller than eukaryotic cells. Instead of a nucleus, they have a single circular strand of DNA that floats freely in the cytoplasm, often called the nucleoid region. Some bacteria also contain small rings of DNA called plasmids, which can carry antibiotic-resistance genes. Bacteria have ribosomes, a cell membrane, a cell wall (peptidoglycan), and sometimes a slime capsule for protection. They may have a flagellum for movement. Bacteria do not contain mitochondria, chloroplasts or a true nucleus.

细菌细胞是原核细胞，比真核细胞小得多。它们没有细胞核，代之以一条单股环状 DNA 自由漂浮在细胞质中，常称为拟核区。一些细菌还含有称为质粒（plasmid）的小 DNA 环，可携带抗生素抗性基因。细菌有核糖体、细胞膜、细胞壁（肽聚糖），有时还有用于保护的荚膜。它们可能有用于运动的鞭毛。细菌没有线粒体、叶绿体或真正的细胞核。

10. Comparing Organelles in Different Cell Types | 不同细胞类型中细胞器的比较

To score full marks on comparison questions, use a table to highlight similarities and differences. The table below summarises the organelles present in animal, plant and bacterial cells. Note that all three have a cell membrane, cytoplasm and ribosomes, which are fundamental to life. Marks are often awarded for stating that plant cells have chloroplasts, a permanent vacuole and a cellulose cell wall; bacterial cells have a cell wall of peptidoglycan, plasmids and no nucleus; animal cells have none of these.

要在比较题中拿到满分，可使用表格突显异同点。下面的表格总结了动物、植物和细菌细胞中存在的细胞器。请注意，所有三种细胞都有细胞膜、细胞质和核糖体，这些是生命的基本要求。题目中常设得分点：植物细胞有叶绿体、中央大液泡和纤维素细胞壁；细菌细胞有肽聚糖细胞壁、质粒且无细胞核；动物细胞这些都没有。

Organelle	Animal Cell	Plant Cell	Bacterial Cell
Nucleus	Yes	Yes	No (free DNA)
Cell membrane	Yes	Yes	Yes
Cytoplasm	Yes	Yes	Yes
Mitochondria	Yes	Yes	No
Ribosomes	Yes	Yes	Yes (smaller)
Chloroplasts	No	Yes	No
Permanent vacuole	No (small temporary)	Yes	No
Cell wall	No	Yes (cellulose)	Yes (peptidoglycan)
Plasmids	No	No	Sometimes

11. How to Label Organelles Correctly in Diagrams | 如何在图上正确标注细胞器

WJEC exam papers frequently require you to label a diagram of a cell. Use a ruler to draw straight label lines, and make sure the line touches the correct structure. Write the organelle name clearly, using the exact term from the specification – e.g., ‘permanent vacuole’ not just ‘vacuole’, and ‘cell membrane’ not ‘plasmalemma’. If the cell is a plant cell, annotate the cell wall, chloroplasts, permanent vacuole and nucleus. For an animal cell, identify the nucleus, cytoplasm, cell membrane and mitochondria. For a bacterial cell, point out the chromosomal DNA, plasmid, cell wall, cell membrane and flagellum if shown.

WJEC 试卷经常要求你在细胞图上标注。用尺子画出笔直的标注线，并确保线接触正确的结构。清楚地写出细胞器名称，使用考纲中的准确术语——例如，写 ‘permanent vacuole’ 而不是仅写 ‘vacuole’，写 ‘cell membrane’ 而不是 ‘plasmalemma’。如果是植物细胞，标注细胞壁、叶绿体、中央大液泡和细胞核。对于动物细胞，辨认细胞核、细胞质、细胞膜和线粒体。至于细菌细胞，指出染色体 DNA、质粒、细胞壁、细胞膜和鞭毛（如果图上显示了）。

12. Common Exam Mistakes and Top Tips | 常见考试错误与高分技巧

Many students lose marks by confusing the nucleus with the vacuole, or by suggesting mitochondria are present in bacterial cells. Remember: bacteria do not have mitochondria. Another mistake is describing the cell wall as ‘impermeable’ – it is fully permeable. When comparing cells, always use precise language such as ‘plant cells have a cellulose cell wall, whereas animal cells do not have a cell wall’. Avoid vague statements. Use the correct order of magnitude: organelles → cells → tissues → organs → organ systems. Finally, practice drawing and labelling cells without notes until you can do it from memory.

许多学生因混淆细胞核与液泡，或声称细菌细胞含有线粒体而丢分。请记住：细菌没有线粒体。另一个常见错误是将细胞壁描述为“不可渗透”——它是全透性的。在比较细胞时，务必使用精确的语言，如“植物细胞有纤维素细胞壁，而动物细胞没有细胞壁”。避免模糊的陈述。使用正确的大小层次：细胞器 → 细胞 → 组织 → 器官 → 器官系统。最后，练习在不看笔记的情况下绘制并标注细胞，直到能凭记忆完成。

Published by TutorHao | Biology Revision Series | aleveler.com

更多咨询请联系16621398022（同微信）