📚 Year 7 WJEC Biology: Unit Test Practice Paper Walkthrough | Year 7 WJEC 生物：单元测试模拟卷解析
Welcome to this walkthrough of a Year 7 WJEC Biology unit test practice paper. We will go through typical questions, model answers and key explanations to help you revise efficiently. Mastering these topics will build a strong foundation for future science studies.
欢迎阅读这篇 Year 7 WJEC 生物单元测试模拟卷解析。我们将浏览典型试题、标准答案和关键解释，帮助你高效复习。掌握这些主题将为未来的科学学习打下坚实基础。
1. How to Use This Practice Paper Walkthrough | 如何使用这份模拟卷解析
First, attempt the practice paper under timed conditions without looking at your notes. Then use this walkthrough to check your answers, correct misconceptions and highlight the exact wording that earns marks. Active revision means writing your own corrected version of every wrong answer.
首先，在不看笔记的情况下限时完成模拟卷。然后用这份解析核对答案、纠正错误概念，并标出能够得分的确切表述。主动复习意味着要把每一道错题都改写成自己的正确答案。
Keep a revision log beside you. For each question, note the topic, the command word and the mark scheme keywords. If you repeatedly lose marks on the same topic, that topic should move to the top of your revision list.
在手边准备一本复习日志。每道题都记下主题、指令词和评分标准关键词。如果同一个主题反复失分，就应该把它排到复习清单的最前面。
Remember that WJEC Year 7 unit tests reward clear scientific vocabulary, correct units and logical structure. A short, precise answer is usually better than a long, vague one.
请记住，WJEC Year 7 单元测试看重清晰的科学词汇、正确的单位和有逻辑的结构。简短准确的回答通常比冗长模糊的回答更好。
2. Paper Structure and Command Words | 试卷结构与指令词
A typical Year 7 WJEC Biology unit test includes multiple-choice questions, short-answer questions, labelling diagrams, simple calculations and questions based on practical work. The paper usually increases in difficulty, so spend roughly one minute per mark.
典型的 Year 7 WJEC 生物单元测试包括选择题、短答题、标注图、简单计算和基于实验的问题。试卷通常由易到难，因此大约每分用一分钟。
Command words tell you what the examiner wants. "Name" or "state" needs a short answer, often one word. "Describe" needs a sequence of observations or steps. "Explain" needs a reason, usually linked by "because". "Compare" needs similarities and differences. "Calculate" needs working and units.
指令词告诉考官想要什么。"Name" 或 "state" 需要简短答案，常常是一个词。"Describe" 需要一系列观察或步骤。"Explain" 需要原因，通常用 "because" 连接。"Compare" 需要相同点和不同点。"Calculate" 需要过程和单位。
For example, if a question says "Explain why the total magnification is 400×", do not just write "10 × 40". Write "he eyepiece is 10× and the objective is 40×, so the total magnification is 10 × 40 = 400×."
例如，如果题目说 "Explain why the total magnification is 400×"，不要只写 "10 × 40"。要写 "he eyepiece is 10× and the objective is 40×, so the total magnification is 10 × 40 = 400×."
Exam tip: Underline the command word before you answer. It stops you from writing too much or too little.
考试提示：作答前先划出指令词。这样可以避免写太多或写太少。
3. The Microscope and Magnification | 显微镜与放大倍数
A common exam question is: " ce lens of 10× magnification and an objective lens of 40×. What is the total magnification?" The answer is 400×. The formula is:
常见考题是："如果显微镜的目镜放大倍数为 10×，物镜放大倍数为 40×，总放大倍数是多少？" 答案是 400×。公式是：
Total magnification = Eyepiece magnification × Objective magnification
总放大倍数 = 目镜放大倍数 × 物镜放大倍数
ys check whether the question asks for the total magnification or the missing lens magnification.
你也可能被要求反向计算。如果总放大倍数是 100×，目镜是 10×，那么物镜一定是 10×，因为 100 ÷ 10 = 10。务必检查题目问的是总放大倍数还是缺失的镜头放大倍数。
gnification with resolution. Magnification makes an image larger; resolution is the ability to distinguish two close points as separate. A higher magnification does not always mean a clearer image.
放大倍数没有单位，但要用乘号表示，例如 400×。不要把放大倍数和分辨率混淆。放大倍数使图像变大；分辨率是分辨两个靠近点的能力。更高的放大倍数并不总是意味着更清晰的图像。
Another typical task is to calculate the actual size of a specimen using a scale bar or the formula:
另一项典型任务是使用比例尺或公式计算标本的实际大小：
Actual size = Image size ÷ Magnification
实际大小 = 图像大小 ÷ 放大倍数
ctual size is 20 mm ÷ 400 = 0.05 mm. You can convert this to 50 μm because 1 mm = 1000 μm.
例如，如果细胞在图中测得 20 mm，放大倍数是 400×，实际大小为 20 mm ÷ 400 = 0.05 mm。因为 1 mm = 1000 μm，所以可以换算成 50 μm。
4. Labelling the Light Microscope | 光学显微镜结构标注
You need to know the main parts of a light microscope and their functions. A labelling question often asks you to identify the eyepiece, objective lens, stage, stage clips, mirror or lamp, coarse focus knob and fine focus knob.
你需要认识光学显微镜的主要部件及其功能。标注题常要求你识别目镜、物镜、载物台、压片夹、反光镜或光源、粗准焦螺旋和细准焦螺旋。
- Eyepiece lens: the lens you look through, usually 10×.
目镜：你观察时用的镜头，通常为 10×。 - Objective lens: the lens closest to the specimen, often 4×, 10× or 40×.
物镜：最靠近标本的镜头，通常为 4×、10× 或 40×。 - Stage: the flat platform where the slide is placed.
载物台：放置玻片的平台。 - Stage clips: hold the slide in position.
压片夹：固定玻片。 - Mirror or lamp: directs light through the specimen.
反光镜或光源：让光线穿过标本。 - Coarse focus knob: moves the stage or lens a large distance to bring the image into view.
粗准焦螺旋：大幅度移动载物台或镜头，使图像进入视野。 - Fine focus knob: moves the stage or lens a small distance to sharpen the image.
细准焦螺旋：小幅度移动载物台或镜头，使图像清晰。
When viewing a slide, always start with the lowest power objective. Use the coarse focus knob first to bring the image into view, then switch to a higher power and only use the fine focus knob to avoid damaging the slide.
观察玻片时，始终从低倍物镜开始。先用粗准焦螺旋找到图像，然后转换到高倍物镜并只能使用细准焦螺旋调焦，以免压碎玻片。
Never use the coarse focus knob when the high-power objective is in place. The objective lens may hit the slide and crack it. This is a common safety point in practical questions.
高倍物镜就位时，绝对不要使用粗准焦螺旋。物镜可能撞到玻片并使其破裂。这是实验题中常见的安全要点。
5. Animal and Plant Cell Structure | 动植物细胞结构
A very frequent question is: "Name three structures found in plant cells but not in animal cells." The answer is cell wall, chloroplasts and a large permanent vacuole. These three structures are the key differences at Year 7 level.
一个非常高频的题目是："说出植物细胞具有而动物细胞没有的三种结构。" 答案是细胞壁、叶绿体和大液泡。在 Year 7 阶段，这三种结构是关键区别。
Both cell types contain a nucleus that controls the cell's activities, cytoplasm where chemical reactions occur, a cell membrane that controls what enters and leaves the cell, and mitochondria where energy is released during respiration. They also contain ribosomes, which are the site of protein synthesis.
两种细胞都含有细胞核，控制细胞活动；细胞质，发生化学反应；细胞膜，控制物质进出；以及线粒体，在呼吸作用中释放能量。它们还含有核糖体，是蛋白质合成的场所。
Plant cells also have a cell wall made of cellulose. It gives the cell a fixed shape and provides support. The large permanent vacuole is filled with cell sap and helps keep the cell firm. Chloroplasts contain chlorophyll, which absorbs light energy for photosynthesis.
植物细胞还有由纤维素组成的细胞壁。它使细胞具有固定形状并提供支持。大液泡充满细胞液，帮助细胞保持坚挺。叶绿体含有叶绿素，吸收光能用于光合作用。
Animal cells do not have a cell wall, chloroplasts or a large permanent vacuole. They may have small temporary vacuoles, but these are not the same as the large permanent vacuole in plant cells. Animal cells also store carbohydrate as glycogen, while plant cells store it as starch or sucrose.
动物细胞没有细胞壁、叶绿体或大液泡。它们可能有小的临时液泡，但这些与植物细胞的大液泡不同。动物细胞还将碳水化合物储存为糖原，而植物细胞储存为淀粉或蔗糖。
Model answer: "Plant cells have a cell wall, chloroplasts and a large permanent vacuole. Animal cells do not have these structures."
标准答案："Plant cells have a cell wall, chloroplasts and a large permanent vacuole. Animal cells do not have these structures."
6. Organelles and Their Functions | 细胞器及其功能
Examiners often ask you to match cell structures with their functions. Learn the following table carefully. The function must be specific, not just "helps the cell".
考官常要求你将细胞结构与功能匹配。请仔细学习下表。功能必须具体，不能只写 "helps the cell"。
| Structure | 结构 | Function | 功能 | Found in | 存在于 |
|---|---|---|
| Nucleus | 细胞核 | Controls cell activities and contains genetic material. | 控制细胞活动，含有遗传物质。 | Both | 两者 |
| Cytoplasm | 细胞质 | Where most chemical reactions take place. | 大多数化学反应发生的场所。 | Both | 两者 |
| Cell membrane | 细胞膜 | Controls what enters and leaves the cell. | 控制物质进出细胞。 | Both | 两者 |
| Mitochondria | 线粒体 | Site of respiration; releases energy. | 呼吸作用场所；释放能量。 | Both | 两者 |
| Ribosomes | 核糖体 | Site of protein synthesis. | 蛋白质合成场所。 | Both | 两者 |
| Cell wall | 细胞壁 | Provides support and fixed shape. | 提供支持和固定形状。 | Plant only | 仅植物 |
| Chloroplast | 叶绿体 | Absorbs light for photosynthesis. | 吸收光能进行光合作用。 | Plant only | 仅植物 |
| Large vacuole | 大液泡 | Stores cell sap and keeps cell firm. | 储存细胞液，保持细胞坚挺。 | Plant only | 仅植物 |
A common mistake is to say that mitochondria make energy. Energy cannot be made; it is released from food during respiration. The correct phrase is "mitochondria release energy" or "mitochondria are the site of respiration".
常见错误是说线粒体制造能量。能量不能被制造；它是在呼吸作用中从食物中释放出来的。正确的说法是 "mitochondria release energy" 或 "mitochondria are the site of respiration"。
7. Specialised Cells and Adaptation | 特化细胞与适应
Specialised cells have structures that help them carry out a particular job. Exam questions often ask you to link a feature to its function. Always write the feature and then explain how it helps the cell.
特化细胞具有帮助它们完成特定工作的结构。考题常要求你把特征与功能联系起来。一定要先写特征，然后解释它如何帮助细胞。
- Red blood cell: no nucleus gives more space for haemoglobin; biconcave shape increases surface area for oxygen uptake.
红细胞：没有细胞核，为血红蛋白留出更多空间；双凹形状增加表面积，有利于吸收氧气。 - Nerve cell: long fibre carries electrical impulses over long distances.
神经细胞：长纤维可以长距离传递电脉冲。 - Sperm cell: tail allows swimming; many mitochondria release energy for movement.
精子细胞：尾部使其游动；大量线粒体释放能量供运动使用。 - Root hair cell: long, thin extension increases surface area for water and mineral uptake.
根毛细胞：细长突起增加表面积，有利于吸收水分和矿物质。 - Muscle cell: contains fibres that can contract, causing movement.
肌肉细胞：含有可收缩的纤维，产生运动。
When answering, avoid vague words such as "better" or "more efficient". Say exactly what the structure does and why that is useful. For example, "The root hair cell has a long extension, which increases the surface area for absorption of water and minerals."
作答时，避免使用 "better" 或 "more efficient" 等模糊词汇。要准确说明结构的作用以及为什么有用。例如："The root hair cell has a long extension, which increases the surface area for absorption of water and minerals."
8. Required Practical: Preparing and Viewing Slides | 必做实验：制作和观察玻片
In the required practical, you may prepare a slide of onion epidermis or a thin plant tissue. The steps are: add a drop of water to the slide, peel a thin layer of tissue, place it in the water, lower a cover slip slowly to avoid air bubbles, and add a stain such as iodine solution if needed.
在必做实验中，你可能会制作洋葱表皮或其他薄植物组织的玻片。步骤是：在玻片上滴一滴水，撕取一薄层组织，放入水中，缓慢放下盖玻片以避免气泡，必要时滴加碘液等染色剂。
Air bubbles appear as dark circles with thick outlines. They are a common problem. To avoid them, lower the cover slip at an angle and gently press down. If bubbles are present, the image will be unclear and you may need to make a new slide.
气泡看起来是带有粗轮廓的黑色圆圈。它们是很常见的问题。避免方法是将盖玻片斜着放下并轻轻按压。如果有气泡，图像会不清晰，可能需要重新制作玻片。
When using the microscope, start with the lowest power objective. Use the coarse focus knob to bring the cells into view. Then rotate to a higher power objective and use only the fine focus knob. Draw what you see and label the cell wall, nucleus and cytoplasm if visible.
使用显微镜时，从最低倍物镜开始。使用粗准焦螺旋使细胞进入视野。然后转到高倍物镜，只能使用细准焦螺旋。画出你所看到的，并在可见时标注细胞壁、细胞核和细胞质。
Safety: handle slides and cover slips carefully because they can break. Keep the microscope away from the edge of the bench. Always carry the microscope with two hands.
安全：小心处理玻片和盖玻片，因为它们容易破碎。让显微镜远离桌边。始终用双手搬运显微镜。
9. Diffusion, Osmosis and Active Transport | 扩散、渗透与主动运输
Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration. It is a passive process, so it does not require energy. Examples include oxygen entering cells and carbon dioxide leaving cells.
扩散是粒子从高浓度区域向低浓度区域的运动。它是被动过程，不需要能量。例如氧气进入细胞，二氧化碳离开细胞。
Osmosis is the movement of water molecules from a dilute solution to a concentrated solution through a partially permeable membrane. It is a special type of diffusion. If a plant cell is placed in pure water, water enters by osmosis, the vacuole expands, and the cell becomes turgid.
渗透是水分子通过半透膜从稀溶液向浓溶液的运动。它是扩散的一种特殊形式。如果把植物细胞放入纯水中，水通过渗透进入，液泡膨胀，细胞变得坚挺。
If a plant cell is placed in a concentrated sugar solution, water leaves by osmosis. The cell membrane may pull away from the cell wall, and the cell becomes plasmolysed. Animal cells may shrink or burst because they do not have a cell wall.
如果把植物细胞放入浓糖水中，水通过渗透离开。细胞膜可能从细胞壁缩回，细胞发生质壁分离。动物细胞因为没有细胞壁，可能会皱缩或破裂。
Active transport is the movement of particles from lower concentration to higher concentration using energy from respiration. It requires carrier proteins in the cell membrane. An example is the uptake of mineral ions by root hair cells.
主动运输是粒子从低浓度向高浓度的运动，利用呼吸作用释放的能量。它需要细胞膜上的载体蛋白。例如根毛细胞吸收矿物质离子。
Model answer: "Osmosis is the movement of water from a dilute solution to a concentrated solution through a partially permeable membrane."
标准答案："Osmosis is the movement of water from a dilute solution to a concentrated solution through a partially permeable membrane."
10. Data, Graphs and Calculations | 数据、图表与计算
Data questions test your ability to read tables, plot graphs and calculate averages. When plotting a graph, label the x-axis with the independent variable and the y-axis with the dependent variable. Include units and use a suitable scale.
数据题考查你阅读表格、绘制图表和计算平均值的能力。绘图时，x 轴标注自变量，y
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