Year 7 CAIE Biology: Formula & Theorem Quick-Reference Handbook | 公式定理速查手册

📚 Year 7 CAIE Biology: Formula & Theorem Quick-Reference Handbook | 公式定理速查手册

This quick-reference handbook collects the essential formulas, equations, and key principles for Year 7 CAIE Biology. Use it to revise core ideas such as cell theory, magnification, photosynthesis, respiration, diffusion, enzyme specificity, energy transfer in food chains, and more. Each section presents the concept in English and Chinese side by side to help you master the subject with confidence.

本速查手册汇集了 Year 7 CAIE 生物核心的公式、方程式和重要定理，包括细胞学说、放大率、光合作用、呼吸作用、扩散、酶的特异性、食物链能量传递等内容。每个要点均以中英对照的形式呈现，帮助你轻松掌握知识要点。

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1. Cell Theory | 细胞学说

All living organisms are made up of cells.

所有生物都由细胞构成。

The cell is the basic structural and functional unit of life.

细胞是生命的基本结构和功能单位。

Cells arise only from pre-existing cells.

细胞只能由已有的细胞分裂产生。

These three statements form the foundation of modern biology and apply to all living things, from bacteria to humans.

这三条核心理论奠定了现代生物学的基础，适用于从细菌到人类的所有生命体。

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2. Magnification Formula | 放大率公式

Magnification is the number of times an image is enlarged compared to the actual object. You can calculate it using the formula:

放大率表示图像比实物放大的倍数，计算公式如下：

Magnification (M) = Image size (I) ÷ Actual size (A)

Where I is the size of the object measured in the drawing or micrograph, and A is its real size. Both must be in the same units before dividing.

其中 I 表示绘图或显微照片中物体的测量尺寸，A 表示物体的实际尺寸。计算时两者必须先统一单位。

For example, if a plant cell measures 15 mm in a photograph but its real length is 0.15 mm, the magnification is 15 ÷ 0.15 = 100×.

例如，若照片中一个植物细胞长 15 mm，而实际长度是 0.15 mm，则放大率为 15 ÷ 0.15 = 100 倍。

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3. Photosynthesis Equation | 光合作用方程式

Photosynthesis is the process by which green plants use light energy to synthesise glucose from carbon dioxide and water. The overall word equation is:

光合作用是绿色植物利用光能，将二氧化碳和水合成为葡萄糖的过程。总文字方程式为：

Carbon dioxide + Water → Glucose + Oxygen

二氧化碳 + 水 → 葡萄糖 + 氧气

The balanced chemical equation, which shows the number of molecules, is:

配平的化学方程式（显示分子数目）为：

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Light energy trapped by chlorophyll in chloroplasts is essential to drive this reaction.

叶绿体中的叶绿素捕获的光能是驱动该反应的必要条件。

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

Aerobic respiration is the process by which cells release energy from glucose using oxygen. The word equation summarises it as:

有氧呼吸是细胞利用氧气从葡萄糖中释放能量的过程。文字方程式概括为：

Glucose + Oxygen → Carbon dioxide + Water (+ energy)

葡萄糖 + 氧气 → 二氧化碳 + 水（+ 能量）

The balanced chemical equation is the opposite of photosynthesis:

配平的化学方程式与光合作用刚好相反：

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy (ATP)

Most of the energy released is stored as a molecule called ATP, which powers metabolic activities.

释放的大部分能量以称为 ATP 的分子形式储存，为代谢活动提供动力。

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5. Gas Exchange and Surface Area : Volume Ratio | 气体交换与表面积体积比

Small organisms can rely on simple diffusion for gas exchange because they have a large surface area to volume ratio. The ratio is calculated as:

小型生物依靠简单的扩散进行气体交换，因为它们具有较大的表面积与体积比。该比值计算公式为：

Surface Area : Volume ratio = Surface Area ÷ Volume

When an organism’s size increases, its volume grows faster than its surface area, so the SA:V ratio decreases. A single-celled organism like Amoeba has a very high SA:V ratio, allowing efficient exchange of oxygen and carbon dioxide across its cell membrane.

当生物体型增大时，体积的增长快于表面积，因此表面积体积比降低。像变形虫这样的单细胞生物具有极高的 SA:V 比，能通过细胞膜高效地进行氧气和二氧化碳的交换。

In larger organisms, specialised gas exchange surfaces (e.g. lungs in mammals, gills in fish) compensate for a lower SA:V ratio.

较大的生物则依靠特化的气体交换表面（如哺乳动物的肺、鱼的鳃）来弥补较低的 SA:V 比。

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6. Diffusion and Osmosis Definitions | 扩散与渗透定义

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 that does not require energy.

扩散是粒子从高浓度区域向低浓度区域净移动的过程，沿浓度梯度进行。它是被动过程，无需消耗能量。

Osmosis is a special type of diffusion. It is the net movement of water molecules through a partially permeable membrane from a solution of higher water potential (dilute solution) to a solution of lower water potential (concentrated solution).

渗透是一种特殊的扩散，指的是水分子通过部分透性膜，从水势较高的溶液（稀溶液）向水势较低的溶液（浓溶液）的净移动。

Both processes are vital for the movement of substances in and out of cells, for example, water uptake by plant roots and oxygen entering blood capillaries.

这两个过程对于物质进出细胞至关重要，例如植物根系吸水、氧气进入毛细血管都依赖于它们。

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7. Enzyme Specificity (Lock and Key Model) | 酶的特异性（锁钥模型）

Enzymes are biological catalysts that speed up chemical reactions in living organisms. Each enzyme has a specific active site that fits only a particular substrate, just as a lock accepts only one key.

酶是生物催化剂，能加速生物体内的化学反应。每种酶都有一个特定的活性位点，只与特定的底物结合，就像一把锁只接受一把钥匙。

The lock and key model explains this: the substrate (key) fits into the enzyme’s active site (lock) to form an enzyme-substrate complex. The reaction then takes place, and products are released, leaving the enzyme unchanged.

锁钥模型解释了这一特性：底物（钥匙）嵌入酶的活性位点（锁）形成酶-底物复合物。随后反应发生，产物释放，酶本身保持不变。

Factors such as temperature and pH can change the shape of the active site (denaturation), stopping the enzyme from working.

温度和 pH 等因素可以改变活性位点的形状（变性），从而使酶失去活性。

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

In a food chain, energy passes from one trophic level to the next, but much of it is lost. On average, only about 10% of the energy is transferred to the next level.

在食物链中，能量从一个营养级传递到下一个营养级，但大部分会散失。通常仅有大约 10% 的能量传递给下一级。

Energy transferred = 10% of the energy from the previous trophic level

传递的能量 = 前一个营养级能量的 10%

Remaining energy is used for life processes (movement, growth, repair) or lost as heat during respiration. This limits the length of food chains and explains why there are usually only 4–5 trophic levels.

其余的能量用于生命活动（运动、生长、修复）或在呼吸过程中以热的形式散失。这一限制决定了食物链的长度，通常只有 4–5 个营养级。

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9. Classification Hierarchy (KPCOFGS) | 生物分类阶层

Living organisms are grouped into a hierarchical system that shows evolutionary relationships. The main taxonomic ranks, from largest to smallest, are:

生物被纳入一个展示进化关系的阶层系统。从大到小的主要分类阶元为：

Kingdom → Phylum → Class → Order → Family → Genus → Species

界 → 门 → 纲 → 目 → 科 → 属 → 种

A common mnemonic is “King Philip Came Over For Good Soup” (or “Keep Ponds Clean Or Frogs Get Sick”). Each level becomes more specific; organisms in the same species can interbreed to produce fertile offspring.

常见的记忆口诀如“King Philip Came Over For Good Soup”。级别越往下越具体；同一物种的生物能杂交产生可育后代。

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10. Testing for Starch and Glucose (Indicators) | 淀粉与葡萄糖检验（指示剂）

Starch and glucose are important carbohydrates. Simple chemical tests identify their presence.

淀粉和葡萄糖是重要的碳水化合物，可以通过简单的化学测试来检验。

Iodine test for starch: Add a few drops of iodine solution to the sample. If starch is present, the iodine turns from yellow-brown to blue-black.

淀粉的碘液检验：向样品中滴加几滴碘液。如果含有淀粉，碘液会从黄褐色变为蓝黑色。

Starch + Iodine solution → Blue-black colour

淀粉 + 碘液 → 蓝黑色

Benedict’s test for glucose (reducing sugars): Add Benedict’s reagent to the sample and heat it in a water bath. If glucose is present, the blue solution gradually changes to green, yellow, orange, and finally brick-red, depending on the concentration.

葡萄糖的本尼迪克特检验（还原糖）：在样品中加入本尼迪克特试剂并水浴加热。若含有葡萄糖，蓝色溶液会随浓度依次变为绿色、黄色、橙色，最终形成砖红色沉淀。

Glucose + Benedict’s reagent (heat) → Brick-red precipitate

葡萄糖 + 本尼迪克特试剂（加热）→ 砖红色沉淀

Published by TutorHao | Biology Revision Series | aleveler.com

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