📚 Year 7 OCR Biology: Key Formulas and Principles Quick Reference Guide | Year 7 OCR 生物：公式定理速查手册
Welcome to your essential Year 7 OCR Biology revision companion. This quick reference guide brings together the most important formulas, definitions, and key principles you will encounter in your studies. Use it to reinforce your understanding and prepare confidently for assessments.
欢迎使用这本 Year 7 OCR 生物学必备复习手册。本速查指南汇集了你在学习过程中会遇到的最重要的公式、定义和关键原理。用它来巩固你的理解，自信地应对考试。
1. The Cell – Basic Unit of Life | 细胞——生命的基本单位
All living organisms are made of cells, the smallest units capable of carrying out life processes. The cell theory states that every living thing is composed of one or more cells, that the cell is the basic structural and functional unit of life, and that all new cells arise from existing cells.
所有生物都由细胞构成，细胞是能够执行生命过程的最小单位。细胞学说指出，所有生物都由一个或多个细胞组成，细胞是生命的基本结构和功能单位，并且所有新细胞都来自已有细胞。
Animal cells typically contain a nucleus, cytoplasm, cell membrane, and mitochondria. Plant cells have all these structures plus a rigid cell wall, a large permanent vacuole, and chloroplasts for photosynthesis.
动物细胞通常包含细胞核、细胞质、细胞膜和线粒体。植物细胞除了这些结构外，还有坚硬的细胞壁、一个大液泡以及用于光合作用的叶绿体。
| Organelle | Function | Animal Cell | Plant Cell |
|---|---|---|---|
| Nucleus | Contains genetic material (DNA) | Yes | Yes |
| Cytoplasm | Jelly-like substance where chemical reactions occur | Yes | Yes |
| Cell membrane | Controls what enters and leaves the cell | Yes | Yes |
| Mitochondria | Site of aerobic respiration, releasing energy | Yes | Yes |
| Cell wall | Made of cellulose, provides support and shape | No | Yes |
| Permanent vacuole | Contains cell sap, helps keep the cell firm | No | Yes |
| Chloroplasts | Contain chlorophyll, absorb light for photosynthesis | No | Yes |
The table above highlights the key differences and shared features of animal and plant cells. Remember that chloroplasts and a cell wall are unique to plant cells and some unicellular organisms.
上表突出了动物细胞和植物细胞的关键异同。记住，叶绿体和细胞壁是植物细胞和某些单细胞生物所特有的结构。
2. Levels of Organisation | 组织层次
In multicellular organisms, cells do not work in isolation. They are organised into a hierarchy: specialised cells form tissues, tissues form organs, organs work together in organ systems, and organ systems make up the whole organism.
在多细胞生物中，细胞并非孤立工作。它们按层级组织：特化的细胞构成组织，组织构成器官，器官协同工作形成器官系统，最终器官系统构成完整的生物体。
For example, muscle cells group together to form muscle tissue. Different tissues, including muscle, nerve, and connective tissue, combine to build the heart, which is an organ. The heart, blood vessels, and blood together form the circulatory system.
例如，肌肉细胞聚集形成肌肉组织。不同的组织，包括肌肉组织、神经组织和结缔组织，共同构成心脏这个器官。心脏、血管和血液一起组成循环系统。
Understanding this organisational principle helps explain how complex life processes, such as digestion and respiration, are broken down into smaller, coordinated functions at each level.
理解这一组织原则有助于解释复杂的生命过程（如消化和呼吸）如何被分解为各个层次上更小、协调的功能。
3. The Photosynthesis Equation | 光合作用方程
Photosynthesis is the fundamental process by which green plants, algae, and some bacteria convert light energy into chemical energy stored in glucose. It takes place in chloroplasts and requires sunlight, carbon dioxide, and water.
光合作用是绿色植物、藻类和某些细菌将光能转化为储存在葡萄糖中的化学能的基本过程。该过程在叶绿体中进行，需要阳光、二氧化碳和水。
The word equation for photosynthesis is:
光合作用的文字方程式为：
carbon dioxide + water → glucose + oxygen
The balanced chemical equation is often written as:
平衡化学方程式通常写作：
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
Chlorophyll, the green pigment in chloroplasts, captures light energy to drive this reaction. The glucose produced is used for growth, repair, and energy storage, while oxygen is released as a by-product.
叶绿体中的绿色色素——叶绿素，捕获光能来驱动该反应。生成的葡萄糖用于生长、修复和能量储存，而氧气则作为副产品释放出来。
4. The Respiration Equation | 呼吸作用方程
Respiration is the process that releases energy from glucose, enabling cells to carry out vital functions. It occurs continuously in all living cells and can be aerobic (using oxygen) or anaerobic (without oxygen).
呼吸作用是从葡萄糖中释放能量的过程，使细胞能够执行重要功能。它持续发生在所有活细胞中，分为有氧呼吸（需要氧气）和无氧呼吸（无需氧气）。
The word equation for aerobic respiration is:
有氧呼吸的文字方程式为：
glucose + oxygen → carbon dioxide + water (+ energy)
The balanced chemical equation is:
平衡化学方程式为：
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O (+ energy)
In human muscle cells during vigorous exercise, when oxygen supply is insufficient, anaerobic respiration occurs: glucose → lactic acid (+ energy). This produces less energy and leads to an oxygen debt.
在剧烈运动时，人体肌肉细胞供氧不足，会发生无氧呼吸：葡萄糖 → 乳酸（+ 能量）。这种方式产生的能量较少，并导致氧债。
5. The Classification System | 分类系统
Biologists classify living organisms into groups based on shared characteristics. The hierarchical classification system arranges these groups from the broadest to the most specific:
生物学家根据共同特征将生物分类。层级分类系统将这些群组从最广泛到最具体排列：
Kingdom → Phylum → Class → Order → Family → Genus → Species
界 → 门 → 纲 → 目 → 科 → 属 → 种
The binomial naming system, developed by Carl Linnaeus, gives each species a two-part Latin name that includes the Genus (capitalised) and the species (lowercase), for example, Homo sapiens for modern humans.
由卡尔·林奈发展的双名法赋予每个物种一个两部分拉丁名，包括属名（首字母大写）和种加词（小写），例如现代人的学名为 Homo sapiens。
The main kingdoms studied in Year 7 include Animals, Plants, Fungi, Protists, and Prokaryotes (bacteria). Each kingdom is distinguished by features such as cell structure, nutrition, and reproduction.
Year 7 阶段主要学习的界包括动物界、植物界、真菌界、原生生物界和原核生物界（细菌）。每个界通过细胞结构、营养方式和繁殖方式等特征加以区分。
6. Food Chains and Energy Transfer | 食物链与能量传递
A food chain illustrates the flow of energy from the sun to producers and then through a series of consumers. Producers, typically green plants, capture sunlight and convert it into chemical energy via photosynthesis.
食物链展示了能量从太阳流向生产者，再通过一系列消费者的过程。生产者，通常是绿色植物，通过光合作用捕获阳光并将其转化为化学能。
Each step in a food chain is called a trophic level. Only about 10% of the energy from one level is passed on to the next. The remaining 90% is used for life processes or lost as heat, which explains why food chains are usually short.
食物链中的每一步称为一个营养级。营养级之间大约只有10%的能量传递到下一级。其余90%用于生命过程或以热的形式散失，这解释了为什么食物链通常较短。
Key terms: producer → primary consumer → secondary consumer → tertiary consumer. Decomposers, such as bacteria and fungi, break down dead matter and recycle nutrients back into the ecosystem.
关键术语：生产者 → 初级消费者 → 次级消费者 → 三级消费者。分解者，如细菌和真菌，分解死去的有机物，并将养分循环回生态系统。
7. Sexual and Asexual Reproduction | 有性繁殖与无性繁殖
Sexual reproduction involves the fusion of male and female gametes (sperm and egg) to form a zygote. This process produces offspring that are genetically different from both parents, increasing variation within a population.
有性繁殖涉及雌雄配子（精子和卵子）融合形成合子。这个过程产生的后代在基因上与双亲不同，增加了种群内的变异。
Asexual reproduction requires only one parent and produces genetically identical offspring, or clones. Examples include budding in yeast, binary fission in bacteria, and the production of runners in strawberry plants.
无性繁殖只需要一个亲本，产生基因相同的后代（克隆）。例如酵母的出芽生殖、细菌的二分裂以及草莓植株产生匍匐茎。
While asexual reproduction allows rapid population growth, sexual reproduction provides the genetic diversity essential for adaptation and survival in changing environments.
无性繁殖可以实现种群快速增长，而有性繁殖则提供了在变化环境中适应和生存所必需的基因多样性。
8. Variation and Inheritance Basics | 变异与遗传基础
Variation refers to the differences between individuals of the same species. It can be continuous, showing a range of values (e.g., height, leaf area), or discontinuous, with distinct categories (e.g., blood group, tongue rolling).
变异指同一物种个体之间的差异。它可以表现为连续的数值范围（如身高、叶面积），也可以是不连续的清晰类别（如血型、卷舌能力）。
DNA, the molecule of inheritance, is organised into structures called chromosomes found in the nucleus. A gene is a section of DNA that codes for a specific protein. Individuals inherit pairs of alleles for each gene, one from each parent.
DNA是遗传的分子基础，它在细胞核内组织成称为染色体的结构。基因是编码特定蛋白质的一段DNA。个体从每个亲本各获得一个等位基因，形成基因对。
A dominant allele (e.g., brown eyes) masks the effect of a recessive allele (e.g., blue eyes) in a heterozygous individual. The phenotype is the observable characteristic, while the genotype is the genetic makeup.
显性等位基因（如棕色眼睛）在杂合子中会掩盖隐性等位基因（如蓝色眼睛）的效应。表现型是可观察的特征，而基因型是遗传组成。
9. Adaptations for Survival | 生存适应
Adaptations are inherited features that enable organisms to survive and reproduce in their specific environments. They can be structural, behavioural, or physiological.
适应性是指使生物体能够在特定环境中生存和繁殖的可遗传特征。它们可以是结构上的、行为上的或生理上的。
Structural adaptations include the thick blubber of seals for insulation, the long neck of a giraffe for reaching high foliage, and the streamlined body of a fish for reducing water resistance.
结构适应包括海豹用于保暖的厚脂肪层、长颈鹿为了够到高处枝叶的长脖子，以及鱼类为减少水流阻力的流线型身体。
Behavioural adaptations include migration of birds to warmer climates, nocturnal activity to avoid daytime heat, and hibernation during winter. Physiological adaptations involve internal processes, such as the production of venom or the ability to conserve water in the kidneys of desert animals.
行为适应包括鸟类迁徙到温暖气候、夜行性活动以避开白日炎热，以及冬季冬眠。生理适应涉及内部过程，例如产生毒液或者沙漠动物肾脏保持水分的能力。
Natural selection is the mechanism by which organisms with advantageous adaptations are more likely to survive and pass on those traits to offspring, gradually changing the population over generations.
自然选择是一种机制，拥有有利适应性的生物更可能存活并将这些性状传给后代，经过世代逐渐改变种群。
10. Key Principles in Ecology | 生态学关键原理
Ecology is the study of interactions between organisms and their environment. A habitat is the place where an organism lives, a population is a group of individuals of the same species in the same habitat, and a community includes all the different populations living together.
生态学是研究生物与环境之间相互作用的学科。栖息地是生物居住的地方，种群是同一栖息地中同一物种的个体群，群落则包括共同生活的所有不同种群。
An ecosystem consists of the community of organisms and the physical (abiotic) factors they interact with, such as light intensity, temperature, soil pH, and water availability. Biotic factors include predation, competition, and disease.
生态系统由生物群落以及它们与之相互作用的物理（非生物）因素组成，例如光照强度、温度、土壤pH值和水分供应。生物因素则包括捕食、竞争和疾病。
Nutrients are constantly recycled in ecosystems. In the carbon cycle, carbon dioxide is removed from the atmosphere by photosynthesis and returned via respiration, combustion, and decomposition. Understanding these cycles is vital for appreciating the balance of nature.
营养物质在生态系统中不断循环。在碳循环中，二氧化碳通过光合作用从大气中移除，并通过呼吸作用、燃烧和分解返回。理解这些循环对于认识自然平衡至关重要。
Published by TutorHao | Biology Revision Series | aleveler.com更多咨询请联系16621398022（同微信）
屏轩国际教育cambridge primary/secondary checkpoint, cat4, ukiset,ukcat,igcse,alevel,PAT,STEP,MAT, ibdp,ap,ssat,sat,sat2课程辅导，国外大学本科硕士研究生博士课程论文辅导