📚 Formula and Theorem Quick Reference Handbook | Year 7 AQA 生物：公式定理速查手册
This quick reference handbook brings together the essential formulas, word equations, and key biological principles that every Year 7 AQA Biology student needs to know. From the microscope magnification formula to the vital cycles of photosynthesis and respiration, these 'laws of biology' will help you understand how living organisms function and interact. Use this guide to check your understanding, prepare for assessments, and build a solid foundation for Key Stage 3 Biology.
这本速查手册汇集了每位 Year 7 AQA 生物学生需要掌握的核心公式、文字方程和关键生物学原理。从显微镜放大公式到光合作用与呼吸作用的重要循环，这些“生物定律”将帮助你理解生物体如何运作和相互作用。你可以用这本指南来检测理解、准备测评，并为 Key Stage 3 生物打下扎实基础。
1. Cell Theory | 细胞学说
Cell theory is a fundamental concept in biology. It states that all living things are composed of one or more cells, and that the cell is the basic structural and functional unit of life. Furthermore, all cells arise from pre-existing cells through cell division.
细胞学说是生物学的基本概念。该学说指出，所有生命体均由一个或多个细胞组成，细胞是生命结构和功能的基本单位。此外，所有细胞都来自已有细胞，通过细胞分裂产生。
In multicellular organisms, cells are specialised to perform different jobs. Groups of similar cells working together form tissues; groups of tissues form organs; and organs work together in organ systems. This organisation allows large organisms to carry out all life processes efficiently.
在多细胞生物中，细胞特化以完成不同的功能。相似的细胞共同组成组织；组织构成器官；器官协同工作构成器官系统。这种组织层次使得大型生物能够高效地进行各项生命活动。
2. Microscope Magnification Formula | 显微镜放大公式
To view cells clearly, we use a light microscope. The total magnification of the image you see is calculated by a simple formula:
Total Magnification = Eyepiece Magnification × Objective Magnification
要清晰地观察细胞，我们使用光学显微镜。你所看到的图像总放大倍数由以下简单公式计算：
总放大倍数 = 目镜放大倍数 × 物镜放大倍数
cord the units correctly and handle the microscope with care, focusing on low power first.
例如，若目镜放大 10 倍，物镜放大 40 倍，则总放大倍数为 10 × 40 = 400 倍。务必正确记录单位，并小心使用显微镜，先从低倍镜开始对焦。
3. Diffusion | 扩散原理
Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration, down a concentration gradient. It is a passive process, meaning it does not require energy from the cell.
扩散是指粒子从高浓度区域向低浓度区域沿浓度梯度进行的净运动。这是一种被动过程，不需要细胞消耗能量。
In living organisms, diffusion is essential for moving substances across cell membranes. For example, oxygen diffuses from the alveoli in the lungs into the blood, and carbon dioxide diffuses from the blood into the lungs to be exhaled. The larger the surface area and the steeper the concentration gradient, the faster the rate of diffusion.
在生物体中，扩散对物质跨越细胞膜的运输至关重要。例如，氧气从肺泡扩散进入血液，二氧化碳从血液扩散进入肺部被呼出。表面积越大，浓度梯度越陡，扩散速率越快。
4. Photosynthesis Word Equation | 光合作用文字方程
Photosynthesis is the process by which green plants and some other organisms use light energy to convert carbon dioxide and water into glucose and oxygen. The word equation summarises this vital reaction:
Carbon dioxide + Water → Glucose + Oxygen
光合作用是绿色植物及部分其他生物利用光能将二氧化碳和水转化为葡萄糖和氧气的过程。文字方程概括了这个重要的反应：
二氧化碳 + 水 → 葡萄糖 + 氧气
This reaction takes place in the chloroplasts of plant cells and requires light energy as well as chlorophyll, the green pigment that captures sunlight. Glucose is used by the plant for energy and growth, while oxygen is released as a by-product into the atmosphere.
该反应发生在植物细胞的叶绿体中，需要光能和捕捉阳光的绿色色素——叶绿素。植物利用葡萄糖提供能量和生长，氧气作为副产品释放到大气中。
5. Aerobic Respiration Word Equation | 有氧呼吸文字方程
Aerobic respiration is the process that releases energy from glucose in the presence of oxygen. It occurs continuously in the mitochondria of plant and animal cells. The word equation is:
Glucose + Oxygen → Carbon dioxide + Water (+ energy released)
有氧呼吸是在氧气存在下从葡萄糖释放能量的过程。它持续发生在动植物细胞的线粒体中。其文字方程为：
葡萄糖 + 氧气 → 二氧化碳 + 水（+ 释放能量）
This reaction is essentially the reverse of photosynthesis. The energy released is used for many life processes, including muscle contraction, maintaining body temperature (in mammals), and building larger molecules from smaller ones. Carbon dioxide and water are waste products that must be removed.
这个反应本质上是光合作用的逆过程。释放的能量用于多种生命活动，包括肌肉收缩、维持体温（哺乳动物）以及从小分子合成大分子。二氧化碳和水是必须被清除的废物。
6. Relationship Between Photosynthesis and Respiration | 光合作用与呼吸作用的关系
Photosynthesis and respiration form a balanced cycle of gases in living organisms. During the day, plants carry out both processes, but photosynthesis usually dominates, producing more oxygen than they use and absorbing more carbon dioxide than they release.
光合作用与呼吸作用在生物体中形成一个平衡的气体循环。白天植物同时进行这两个过程，但光合作用通常占主导，产生的氧气多于消耗的，吸收的二氧化碳多于释放的。
At night, photosynthesis stops because there is no light, but respiration continues. This means plants take in oxygen and release carbon dioxide at night, just like animals. Overall, the two processes help to maintain the balance of oxygen and carbon dioxide in the atmosphere.
夜晚，由于没有光照，光合作用停止，但呼吸作用持续进行。这意味着植物会在夜晚像动物一样吸收氧气并释放二氧化碳。总体而言，这两个过程有助于维持大气中氧气和二氧化碳的平衡。
7. Energy Transfer in Food Chains | 食物链能量传递
Food chains show the transfer of energy from one organism to another. Energy enters most food chains through producers (green plants), which convert light energy into chemical energy during photosynthesis. When consumers eat producers or other consumers, energy is passed along the chain.
食物链展示了能量从一个生物体传递到另一个生物体的过程。能量通过生产者（绿色植物）进入大多数食物链，生产者在光合作用中把光能转化为化学能。消费者吃了生产者或其他消费者后，能量沿食物链传递。
However, energy transfer is not 100% efficient. At each trophic level, a large amount of energy is lost through respiration, movement, heat, and uneaten parts. Only about 10% of the energy is typically transferred to the next level. This is why food chains are rarely longer than four or five levels.
然而，能量传递并非百分之百有效。在每一个营养级，大部分能量通过呼吸、运动、散热和未被吃掉的部分丢失。通常只有约 10% 的能量传递到下一级。这就是为什么食物链很少超过四到五个层级的缘故。
8. Digestion and Enzymes | 消化与酶的作用
Digestion is the breakdown of large, insoluble food molecules into small, soluble molecules that can be absorbed into the blood. This process is achieved by enzymes, which are biological catalysts that speed up chemical reactions without being used up.
消化是指将大型不溶性食物分子分解成能被吸收进入血液的小型可溶性分子的过程。这一过程由酶来完成，酶是生物催化剂，能加速化学反应而自身不被消耗。
Different enzymes work on specific substrates. For example, carbohydrases break down carbohydrates like starch into simple sugars, proteases break down proteins into amino acids, and lipases break down fats into fatty acids and glycerol. The small soluble products are then absorbed in the small intestine.
不同的酶作用于特定的底物。例如，碳水化合物酶将淀粉等碳水化合物分解为单糖，蛋白酶将蛋白质分解为氨基酸，脂肪酶将脂肪分解为脂肪酸和甘油。这些小分子可溶性产物随后在小肠被吸收。
9. Gas Exchange in the Lungs | 肺部气体交换
Breathing, or ventilation, brings fresh air into the lungs and removes stale air. In the lungs, gas exchange takes place in millions of tiny air sacs called alveoli. Here, oxygen from the inhaled air diffuses into the blood, while carbon dioxide diffuses from the blood into the air to be exhaled.
呼吸（换气）将新鲜空气吸入肺部并排出浊气。在肺部，气体交换在数百万个称为肺泡的微小气囊中进行。在这里，吸入空气中的氧气扩散进入血液，而血液中的二氧化碳扩散进入空气被呼出。
The alveoli are adapted for efficient gas exchange: they have very thin walls (one cell thick), a large surface area, a good blood supply, and are moist. These features reduce the distance for diffusion and maintain a steep concentration gradient, ensuring a rapid rate of exchange.
肺泡适于高效气体交换：它们具有极薄的壁（仅一个细胞厚）、巨大的表面积、丰富的血液供应和潮湿的环境。这些特征缩短了扩散距离并维持了陡峭的浓度梯度，从而保证了快速的交换速率。
10. Circulatory System Overview | 循环系统概述
The circulatory system consists of the heart, blood vessels, and blood. The heart acts as a muscular pump that pushes blood around the body. Arteries carry blood away from the heart to the organs; veins return blood to the heart; and capillaries connect them, allowing the exchange of substances with cells.
循环系统由心脏、血管和血液组成。心脏就像一个肌肉泵，将血液推送到全身。动脉将血液从心脏输送到器官；静脉将血液送回心脏；毛细血管连接两者，允许物质与细胞进行交换。
Blood transports oxygen, nutrients, hormones, and waste products. Red blood cells contain haemoglobin, which binds to oxygen for transport. Plasma carries dissolved food, carbon dioxide, and other substances. The double circulatory system in humans means blood passes through the heart twice on one complete circuit of the body.
血液运输氧气、营养物质、激素和废物。红细胞含有血红蛋白，能与氧气结合进行输送。血浆运载溶解的食物、二氧化碳和其他物质。人类的双循环系统意味着血液在一次完整的体循环中两次流经心脏。
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