Year 7 Cambridge Biology: Formulas & Key Principles Cheat Sheet | Year 7 Cambridge 生物：公式定理速查手册

📚 Year 7 Cambridge Biology: Formulas & Key Principles Cheat Sheet | Year 7 Cambridge 生物：公式定理速查手册

Welcome to your ultimate quick-reference guide for Year 7 Cambridge Biology. This handbook compiles the essential formulas, equations and principles you need to master – from calculating microscope magnification to understanding the equations of photosynthesis and respiration. Keep it handy for revision!

欢迎使用 Year 7 Cambridge 生物的终极速查手册。本手册汇编了你需要掌握的关键公式、方程式和原理——从计算显微镜放大倍率到理解光合作用与呼吸作用的方程式。把它放在手边用于复习！

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1. Magnification Formula | 放大倍率公式

To calculate the total magnification of a microscope, multiply the magnification of the eyepiece lens by the magnification of the objective lens.

要计算显微镜的总放大倍率，将目镜的放大倍率乘以物镜的放大倍率。

Total Magnification = Eyepiece Magnification × Objective Magnification

总放大倍率 = 目镜放大倍率 × 物镜放大倍率

For example, if the eyepiece is 10× and the objective is 40×, the total magnification is 10 × 40 = 400×.

例如，如果目镜是 10×，物镜是 40×，总放大倍率为 10 × 40 = 400×。

Always start with the lowest power objective to locate the specimen, then switch to higher powers to see more detail.

总是先用低倍物镜找到标本，然后换用高倍镜观察更多细节。

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2. Photosynthesis Equation | 光合作用方程式

Photosynthesis is the process by which green plants use light energy to convert carbon dioxide and water into glucose and oxygen.

光合作用是绿色植物利用光能，将二氧化碳和水转化为葡萄糖和氧气的过程。

carbon dioxide + water → glucose + oxygen

二氧化碳 + 水 → 葡萄糖 + 氧气

This reaction occurs in the chloroplasts and requires chlorophyll. The balanced chemical equation is: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂.

该反应发生在叶绿体中，需要叶绿素。配平的化学方程式为：6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂。

Light energy is captured by chlorophyll and converted into chemical energy stored in glucose.

光能被叶绿素捕获，并转化为储存在葡萄糖中的化学能。

You can test for the production of starch (a storage form of glucose) in leaves using iodine solution.

你可以用碘液检测叶片中是否产生了淀粉（葡萄糖的储存形式）。

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3. Aerobic Respiration Equation | 有氧呼吸方程式

Aerobic respiration releases energy from glucose using oxygen, which takes place in the mitochondria of cells.

有氧呼吸利用氧气从葡萄糖中释放能量，这发生在细胞的线粒体中。

glucose + oxygen → carbon dioxide + water + energy

葡萄糖 + 氧气 → 二氧化碳 + 水 + 能量

The balanced chemical equation is: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O (+ energy as ATP).

配平的化学方程式为：C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O（以 ATP 形式释放能量）。

All living organisms carry out respiration continuously to power life processes such as growth, movement and repair.

所有生物都不断进行呼吸作用，为生长、运动和修复等生命过程供能。

The carbon dioxide produced can be detected using limewater, which turns from colourless to cloudy.

产生的二氧化碳可用石灰水检测，石灰水会从无色变为浑浊。

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4. Anaerobic Respiration Equations | 无氧呼吸方程式

When oxygen is scarce, some cells can release energy through anaerobic respiration, which produces less energy than aerobic respiration.

当氧气不足时，一些细胞能通过无氧呼吸释放能量，但产生的能量比有氧呼吸少。

In human muscles during strenuous exercise, anaerobic respiration produces lactic acid.

在人体剧烈运动时，肌肉中的无氧呼吸产生乳酸。

glucose → lactic acid + energy

葡萄糖 → 乳酸 + 能量

The build-up of lactic acid causes muscle fatigue and cramps. Oxygen debt must be repaid by breathing heavily after exercise.

乳酸的积累会导致肌肉疲劳和抽筋。运动后需通过大喘气来偿还氧债。

In yeast and some plants, anaerobic respiration (fermentation) produces ethanol and carbon dioxide.

在酵母和某些植物中，无氧呼吸（发酵）产生乙醇和二氧化碳。

glucose → ethanol + carbon dioxide + energy

葡萄糖 → 乙醇 + 二氧化碳 + 能量

Fermentation is used in baking (to make bread rise) and brewing (to produce alcohol).

发酵用于烘焙（使面包膨胀）和酿造（生产酒精）。

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5. MRS GREN: Characteristics of Life | MRS GREN：生命特征定理

The acronym MRS GREN helps you remember the seven life processes shared by all living organisms.

首字母缩略词 MRS GREN 可帮助你记住所有生物共有的七大生命过程。

• Movement – an action by an organism causing a change of position or place.

  运动 (Movement) – 生物体引起位置改变的行为。

• Respiration – the release of energy from food substances in cells.

  呼吸 (Respiration) – 细胞内从食物物质中释放能量。

• Sensitivity – the ability to detect and respond to changes in the environment.

  感应 (Sensitivity) – 探测并响应环境变化的能力。

• Growth – a permanent increase in size and dry mass.

  生长 (Growth) – 体积和干重的永久增加。

• Reproduction – the processes that make more of the same kind of organism.

  生殖 (Reproduction) – 产生更多同类生物的过程。

• Excretion – the removal of toxic waste products of metabolism.

  排泄 (Excretion) – 清除代谢产生的有毒废物。

• Nutrition – the intake of materials for energy, growth and repair.

  营养 (Nutrition) – 为能量、生长和修复摄取物质。

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6. Food Test Principles | 食物测试原理

Simple chemical tests can identify the presence of key nutrients in food samples. The colour change indicates a positive result.

简单的化学测试可以鉴定食物样品中是否存在关键营养素。颜色变化表明阳性结果。

Benedict’s test for reducing sugars: Add Benedict’s solution and heat in a water bath. A positive result turns from blue to brick-red precipitate.

本尼迪克特测试还原糖：加入本尼迪克特溶液并在水浴中加热。阳性结果由蓝色变为砖红色沉淀。

Iodine test for starch: Add a few drops of iodine solution. The colour changes from yellow-brown to blue-black in the presence of starch.

碘液测试淀粉：滴加几滴碘液。有淀粉存在时颜色由黄褐色变为蓝黑色。

Biuret test for proteins: Add sodium hydroxide solution, then copper sulfate solution. A purple colour indicates protein.

双缩脲测试蛋白质：加入氢氧化钠溶液，然后加入硫酸铜溶液。出现紫色表示有蛋白质。

Ethanol emulsion test for fats: Shake the sample with ethanol and pour into water. A white cloudy emulsion indicates lipids.

乙醇乳液测试脂肪：用乙醇振荡样品，再倒入水中。出现白色浑浊乳液表明有脂质。

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7. Cell Theory and Organelle Functions | 细胞学说和细胞器功能定理

Cell theory states that all living things are made of cells, the cell is the basic unit of structure and function, and all cells come from pre-existing cells.

细胞学说指出：所有生物由细胞组成，细胞是结构和功能的基本单位，所有细胞都来自已有的细胞。

Both animal and plant cells contain a nucleus, cytoplasm, cell membrane and mitochondria. Plant cells also have a cell wall, chloroplasts and a large permanent vacuole.

动植物细胞都含有细胞核、细胞质、细胞膜和线粒体。植物细胞还有细胞壁、叶绿体和一个大液泡。

The nucleus controls cell activities and contains genetic material (DNA). The cytoplasm is where most chemical reactions occur. The cell membrane controls the movement of substances in and out.

细胞核控制细胞活动并含有遗传物质 (DNA)；细胞质是大多数化学反应发生的场所；细胞膜控制物质的进出。

Chloroplasts absorb light for photosynthesis, mitochondria carry out respiration, and the vacuole stores cell sap and helps maintain rigidity.

叶绿体吸收光线进行光合作用，线粒体进行呼吸作用，液泡储存细胞液并帮助维持硬度。

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8. Energy Transfer in Food Chains (10% Rule) | 食物链中的能量传递（10%定律）

Food chains show the flow of energy from producer to primary consumer, secondary consumer and so on. At each trophic level, only about 10% of the energy is passed on.

食物链显示了能量从生产者到初级消费者、次级消费者等的流动。在每个营养级，只有约 10% 的能量被传递下去。

The remaining 90% is lost as heat from respiration, used in movement or lost in waste materials. This limits the length of food chains.

剩余的 90% 以呼吸作用的热能、运动消耗或废物形式散失。这限制了食物链的长度。

Energy available at next level ≈ 10% × Energy in previous level

下一营养级可用能量 ≈ 10% × 上一营养级的能量

Producers (plants) have the most energy, while top predators have the least. Pyramid of energy diagrams always show an upright shape.

生产者（植物）拥有最多能量，而顶级消费者最少。能量金字塔总是呈正立的形状。

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9. Diffusion, Osmosis, and Active Transport Principles | 扩散、渗透和主动运输原理

Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration, down the concentration gradient. It is a passive process and does not require energy.

扩散是粒子从高浓度区域向低浓度区域沿浓度梯度的净移动。它是一个被动过程，不需要能量。

Osmosis is the diffusion of water molecules through a partially permeable membrane from a dilute solution (high water potential) to a more concentrated solution (low water potential).

渗透是水分子通过半透膜，从稀溶液（高水势）向较浓溶液（低水势）的扩散。

Active transport moves substances against the concentration gradient – from low to high concentration – using energy from respiration. It requires carrier proteins in cell membranes.

主动运输逆浓度梯度——从低浓度到高浓度——利用呼吸作用提供的能量。它需要细胞膜中的载体蛋白。

For example, root hair cells absorb mineral ions by active transport, even when their concentration inside the cell is already higher than in the soil.

例如，根毛细胞通过主动运输吸收矿质离子，即使细胞内浓度已高于土壤中的浓度。

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10. Enzyme Activity and Optimal Conditions | 酶活性和最佳条件

Enzymes are biological catalysts that speed up reactions without being used up. They are made of protein and have an active site complementary to their specific substrate.

酶是生物催化剂，能加速反应而自身不被消耗。它们由蛋白质组成，拥有与其特定底物互补的活性位点。

Enzyme activity is affected by temperature and pH. Each enzyme has an optimum temperature (in humans around 37 °C) and an optimum pH (e.g. around pH 2 for pepsin in the stomach).

酶活性受温度和 pH 影响。每种酶都有最适温度（人体内约 37 °C）和最适 pH（例如胃蛋白酶的最适 pH 约为 2）。

At very high temperatures, enzymes denature – the active site changes shape irreversibly and the substrate can no longer fit.

在极高温下，酶会变性——活性位点不可逆地改变形状，底物不再能契合。

At very low temperatures, enzymes are inactive but usually do not denature; they can work again when warmed.

在极低温下，酶失活但通常不变性；升温后可恢复活性。

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11. Taxonomic Hierarchy | 生物分类层级

Biologists classify organisms into groups based on shared features. The five kingdoms are Animals, Plants, Fungi, Protists and Prokaryotes.

生物学家根据共同特征对生物进行分类。五个界为：动物界、植物界、真菌界、原生生物界和原核生物界。

The taxonomic hierarchy (from largest to smallest) is: Kingdom, Phylum, Class, Order, Family, Genus, Species.

分类层级（从大到小）为：界、门、纲、目、科、属、种。

A mnemonic to remember the order is ‘King Philip Came Over For Good Soup’.

记忆该顺序的口诀是：“King Philip Came Over For Good Soup”（或中文：界门纲目科属种）。

The binomial naming system gives each species a two-part Latin name: the genus with a capital letter and the species in lower case (e.g. Homo sapiens).

双名法赋予每个物种一个由两部分组成的拉丁名：属名首字母大写，种名全小写（例如 Homo sapiens）。

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12. Balanced Diet and Nutrient Functions | 均衡膳食与营养素功能

A balanced diet includes the correct proportions of seven essential nutrients. The table below summarises their main functions.

均衡膳食包含正确比例的七种必需营养素。下表总结了它们的主要功能。

Nutrient	Key Functions
Carbohydrates	Provide energy; glucose is used in respiration.
Proteins	Growth and repair of tissues; enzymes, hormones and antibodies.
Lipids (fats and oils)	Energy store, insulation, protection of organs, cell membranes.
Vitamins	E.g. Vitamin C for healthy skin and gums, Vitamin D for calcium absorption.
Minerals	E.g. Calcium for strong bones and teeth, Iron for haemoglobin in red blood cells.
Water	Solvent for chemical reactions, transport, temperature regulation.
Dietary fibre	Helps move food through the digestive system and prevents constipation.

对应的中文营养素功能概括：碳水化合物提供能量；蛋白质用于生长和修复；脂类储存能量并构成细胞膜；维生素和矿物质各司其职，如维生素 C 维护皮肤健康，钙强健骨骼；水是化学反应溶剂；膳食纤维促进肠道蠕动。

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