📚 Year 9 SQA Biology: Core Knowledge Review | 九年级 SQA 生物：核心知识点梳理
Year 9 SQA Biology builds the essential foundation for understanding life at the cellular, organism, and ecosystem levels. This article reviews the core topics covered in the Scottish curriculum, including cells, transport, enzymes, photosynthesis, respiration, genetics, ecology, and human body systems. By mastering these key concepts, students will be well-prepared for further study at National 4 and 5 levels.
九年级 SQA 生物课程为理解细胞、生物体和生态系统层面的生命现象奠定了重要基础。本文梳理了苏格兰课程涵盖的核心主题，包括细胞、物质运输、酶、光合作用、呼吸作用、遗传、生态以及人体系统。掌握这些关键概念后，学生将为后续国家 4 级和 5 级的学习做好充分准备。
1. Cell Structure and Function | 细胞结构与功能
All living organisms are made of cells. Animal cells contain a cell membrane, cytoplasm, nucleus, mitochondria, and ribosomes. Plant cells have the same organelles plus a rigid cell wall made of cellulose, a large permanent vacuole, and chloroplasts that carry out photosynthesis.
所有生物都由细胞构成。动物细胞含有细胞膜、细胞质、细胞核、线粒体和核糖体。植物细胞拥有相同的细胞器，还多了一个由纤维素组成的坚固细胞壁、一个大的中央液泡以及进行光合作用的叶绿体。
The nucleus stores genetic material (DNA) and controls cell activities. Mitochondria are the site of aerobic respiration, releasing energy from food. Ribosomes make proteins by assembling amino acids. Chloroplasts contain chlorophyll, which captures light energy for photosynthesis.
细胞核储存遗传物质 (DNA) 并控制细胞活动。线粒体是有氧呼吸的场所，从食物中释放能量。核糖体通过组装氨基酸制造蛋白质。叶绿体含有叶绿素，能捕获光能用于光合作用。
2. Transport Across Cell Membranes | 细胞膜的物质运输
Substances move in and out of cells through the cell membrane. 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 that does not require energy. Oxygen and carbon dioxide move by diffusion during gas exchange.
物质通过细胞膜进出细胞。扩散是指粒子从较高浓度区域向较低浓度区域的净移动，沿浓度梯度进行。这是一种被动过程，不需要能量。氧气和二氧化碳在气体交换时以扩散方式移动。
Osmosis is a special type of diffusion involving water molecules. It is the movement of water from a dilute solution (high water potential) to a more concentrated solution (low water potential) through a partially permeable membrane. Plant cells rely on osmosis to maintain turgor pressure, which keeps the plant upright.
渗透是扩散的一种特殊类型，涉及水分子。它是水从稀释溶液（高水势）通过部分透性膜向更浓溶液（低水势）的移动。植物细胞依靠渗透维持膨压，使植物保持挺立。
Active transport is the movement of particles against a concentration gradient, from low to high concentration. This process requires energy from respiration and is carried out by carrier proteins in the membrane. Root hair cells absorb mineral ions from the soil by active transport.
主动运输是粒子逆浓度梯度移动的过程，即从低浓度向高浓度移动。这个过程需要呼吸作用提供的能量，并由细胞膜上的载体蛋白完成。根毛细胞通过主动运输从土壤中吸收矿质离子。
3. Enzymes and Metabolism | 酶与新陈代谢
Enzymes are biological catalysts made of protein that speed up chemical reactions in living organisms without being used up. Each enzyme has a specific active site with a shape that fits its particular substrate, like a lock and key. This is called the lock-and-key model. The substrate binds to the active site, the reaction occurs, and products are released.
酶是由蛋白质构成的生物催化剂，能加速生物体内的化学反应而自身不被消耗。每种酶都有一个特定的活性位点，其形状能匹配特定的底物，就像锁和钥匙一样，这被称为锁钥模型。底物与活性位点结合，反应发生，产物被释放。
Enzyme activity is affected by temperature and pH. Each enzyme works best at its optimum temperature and pH. In humans, most enzymes have an optimum temperature around 37 °C. High temperatures can denature enzymes, changing the shape of the active site so the substrate can no longer bind. Extreme pH values also cause denaturation.
酶的活性受温度和 pH 值影响。每种酶在其最适温度和 pH 值下活性最高。在人体中，大多数酶的最适温度约为 37 °C。高温会使酶变性，改变活性位点的形状，底物便无法结合。极端的 pH 值也会导致变性。
Digestive enzymes break down large food molecules into smaller, soluble ones that can be absorbed. Amylase breaks down starch into maltose; protease breaks down proteins into amino acids; lipase breaks down fats into fatty acids and glycerol.
消化酶将大分子食物分解为可吸收的小分子可溶性物质。淀粉酶将淀粉分解为麦芽糖；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。
4. Photosynthesis | 光合作用
Photosynthesis is the process by which green plants and some other organisms use light energy to produce glucose from carbon dioxide and water. It takes place in the chloroplasts of plant cells. The overall word equation is:
光合作用是绿色植物和其他一些生物利用光能将二氧化碳和水转化为葡萄糖的过程。它发生在植物细胞的叶绿体中。总文字方程式为：
carbon dioxide + water → glucose + oxygen
二氧化碳 + 水 → 葡萄糖 + 氧气
The rate of photosynthesis is affected by light intensity, carbon dioxide concentration, and temperature. Limiting factors slow down the rate when they are in short supply. For example, on a bright, warm day, carbon dioxide concentration may be the limiting factor, while at low light levels, light intensity is limiting.
光合作用的速率受光照强度、二氧化碳浓度和温度的影响。限制因素在供应不足时会降低反应速率。例如，在明亮的温暖日子里，二氧化碳浓度可能成为限制因素，而在低光照水平下，光照强度则是限制因素。
Glucose produced in photosynthesis is used for respiration to provide energy, converted into starch for storage, used to make cellulose for cell walls, and combined with other molecules to form proteins and lipids.
光合作用产生的葡萄糖用于呼吸作用以提供能量，转化为淀粉储存，用于制造细胞壁的纤维素，以及与其他分子结合形成蛋白质和脂质。
5. Respiration | 呼吸作用
Respiration is the process that releases energy from glucose in all living cells. It is not the same as breathing (ventilation). Aerobic respiration uses oxygen and produces a large amount of energy. The word equation is:
呼吸作用是所有活细胞从葡萄糖中释放能量的过程，它与呼吸（通气）不是一回事。有氧呼吸利用氧气并产生大量能量。文字方程式为：
glucose + oxygen → carbon dioxide + water (+ energy)
葡萄糖 + 氧气 → 二氧化碳 + 水 (+ 能量)
Anaerobic respiration occurs when oxygen is absent or in short supply, for example during vigorous exercise in muscle cells. In animals, it produces lactic acid and a small amount of energy. In yeast and some plants, anaerobic respiration produces ethanol and carbon dioxide – a process called fermentation.
无氧呼吸发生在缺氧或供氧不足时，例如肌肉细胞剧烈运动时。在动物体内，它产生乳酸和少量能量。在酵母和一些植物中，无氧呼吸产生乙醇和二氧化碳——这一过程称为发酵。
glucose → lactic acid (+ some energy)
葡萄糖 → 乳酸 (+ 一些能量)
glucose → ethanol + carbon dioxide (+ some energy)
葡萄糖 → 乙醇 + 二氧化碳 (+ 一些能量)
Energy released during respiration is used for muscle contraction, active transport, maintaining body temperature, and building new molecules such as proteins and DNA.
呼吸作用释放的能量用于肌肉收缩、主动运输、维持体温以及构建新分子如蛋白质和 DNA。
6. DNA and Inheritance | DNA 与遗传
DNA (deoxyribonucleic acid) is the molecule that carries genetic information in almost all living organisms. It is found in the nucleus of cells, arranged into structures called chromosomes. A gene is a section of DNA that codes for a specific protein. Different versions of the same gene are called alleles.
DNA（脱氧核糖核酸）是几乎所有生物体内携带遗传信息的分子。它位于细胞核中，组装成称为染色体的结构。基因是编码特定蛋白质的一段 DNA。同一基因的不同版本叫做等位基因。
Alleles can be dominant or recessive. If an individual has two different alleles for a trait, the dominant allele is expressed, masking the effect of the recessive allele. The combination of alleles an organism has is its genotype, while the observable characteristics make up its phenotype.
等位基因有显性和隐性之分。如果个体对某一性状拥有两个不同的等位基因，显性等位基因会表达，掩盖了隐性等位基因的作用。生物所具有的等位基因组合称为基因型，可观察到的特征总和则是表现型。
Genetic crosses and Punnett squares can be used to predict the probability of offspring inheriting particular characteristics. If both parents are heterozygous (e.g., Bb) for a trait, there is a 75% chance of the offspring showing the dominant trait and a 25% chance of showing the recessive trait.
遗传杂交和庞纳特方格可用于预测后代继承特定性状的概率。如果父母双方对某一性状都是杂合子（例如 Bb），后代表现出显性性状的概率是 75%，表现出隐性性状的概率是 25%。
7. Cell Division: Mitosis and Meiosis | 细胞分裂：有丝分裂与减数分裂
Mitosis is used for growth, repair, and asexual reproduction. It produces two genetically identical daughter cells with the same number of chromosomes as the parent cell. In humans, body cells are diploid, containing 46 chromosomes (23 pairs).
有丝分裂用于生长、修复和无性生殖。它产生两个遗传上完全相同的子细胞，染色体数目与母细胞相同。人体中，体细胞是二倍体，含有 46 条染色体（23 对）。
Meiosis produces gametes (sperm and egg cells) for sexual reproduction. It involves two divisions, resulting in four haploid daughter cells, each with half the number of chromosomes (23 in humans). This ensures that when fertilisation occurs, the zygote restores the full diploid number. Meiosis also introduces genetic variation through independent assortment and crossing over.
减数分裂产生用于有性生殖的配子（精子和卵细胞）。它涉及两次分裂，产生四个单倍体子细胞，每个细胞染色体数目减半（人类为 23 条）。这确保了受精发生时，受精卵恢复完整的二倍体数目。减数分裂还通过独立分配和交叉互换引入遗传变异。
8. Ecology: Food Chains and Ecosystems | 生态学：食物链与生态系统
ergy from one organism to another, starting with a producer (usually a green plant) that makes its own food by photosynthesis. Examples: grass → rabbit → fox.
生态系统是一个生物群落与它们所处的非生物环境相互作用的体系。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，始于生产者（通常是绿色植物），它通过光合作用制造食物。例如：草 → 兔子 → 狐狸。
At each trophic level, energy is lost as heat through respiration, movement, and undigested materials. This limits the length of food chains. Pyramids of number and pyramids of biomass represent the number of organisms or the total mass at each level. In a typical pyramid of biomass, the producer level has the greatest biomass.
在每一营养级上，能量会通过呼吸、运动以及未消化的物质以热能形式散失。这限制了食物链的长度。数量金字塔和生物量金字塔分别代表每个层级上的个体数目或总质量。在典型的生物量金字塔中，生产者层级的生物量最大。
Biodiversity is the variety of different species in an area. It can be affected by pollution, habitat destruction, and climate change. Conservation methods such as protecting habitats and captive breeding help maintain biodiversity.
生物多样性是一个地区内不同物种的多样性。它会受到污染、栖息地破坏和气候变化的影响。保护栖息地、圈养繁殖等保护方法有助于维持生物多样性。
9. Human Digestive System | 人类消化系统
Digestion breaks down large, insoluble food molecules into small, soluble ones that can be absorbed into the blood. Mechanical digestion (chewing in the mouth, churning in the stomach) increases the surface area for enzymes. Chemical digestion uses enzymes to hydrolyse molecules.
消化将大而不溶的食物分子分解为可溶的小分子，以便吸收到血液中。物理消化（口腔中的咀嚼、胃的搅拌）增加了酶作用的表面积。化学消化则利用酶来水解分子。
Key organs and enzymes: Salivary glands secrete amylase to break down starch. The stomach produces protease (pepsin) and hydrochloric acid to kill bacteria and provide an acidic pH. The pancreas releases amylase, protease, and lipase into the small intestine. The small intestine is where most digestion is completed and absorption occurs through finger-like villi. The large intestine absorbs water.
关键器官和酶：唾液腺分泌淀粉酶分解淀粉。胃产生蛋白酶（胃蛋白酶）和盐酸，以杀死细菌并提供酸性 pH 环境。胰腺向小肠分泌淀粉酶、蛋白酶和脂肪酶。小肠是大部分消化完成和吸收发生的地方，吸收通过指状绒毛进行。大肠吸收水分。
Villi have a thin one-cell-thick lining, a dense capillary network, and a lacteal to transport absorbed nutrients. These adaptations maximise the rate of absorption by diffusion and active transport.
绒毛具有单细胞厚的薄壁、密集的毛细血管网和运输吸收营养的乳糜管。这些适应特性通过扩散和主动运输最大限度地提高了吸收速率。
10. Circulatory System | 循环系统
The human circulatory system consists of the heart, blood vessels, and blood. It transports oxygen, nutrients, hormones, and waste products around the body. The heart is a double pump: the right side pumps deoxygenated blood to the lungs (pulmonary circulation), and the left side pumps oxygenated blood to the rest of the body (systemic circulation).
人体循环系统由心脏、血管和血液组成，负责在全身运输氧气、营养、激素和废物。心脏是一个双泵：右侧将缺氧血泵送至肺部（肺循环），左侧将充氧血泵送至全身其他部位（体循环）。
Blood vessels include arteries (thick, muscular walls, carry blood away from the heart under high pressure), veins (thinner walls, contain valves to prevent backflow, carry blood towards the heart), and capillaries (one-cell-thick walls for efficient exchange of substances).
血管包括动脉（壁厚、有肌肉，将血液带离心脏，血压高）、静脉（壁较薄，有瓣膜防止回流，将血液送回心脏）和毛细血管（单细胞厚的壁，便于高效的物质交换）。
Blood consists of red blood cells (carry oxygen using haemoglobin), white blood cells (defend against infection), platelets (involved in blood clotting), and plasma (the liquid component carrying dissolved substances).
血液由红细胞（利用血红蛋白携带氧气）、白细胞（防御感染）、血小板（参与凝血）和血浆（携带溶解物质的液体组分）组成。
11. Human Reproduction | 人类生殖
Puberty involves hormonal changes leading to the production of gametes. In males, the testes produce sperm and the hormone testosterone. In females, the ovaries release eggs (ova) and produce oestrogen and progesterone. The menstrual cycle lasts about 28 days and includes ovulation around day 14.
青春期涉及激素变化，导致配子的产生。男性睾丸产生精子和激素睾酮。女性卵巢释放卵子并产生雌激素和孕酮。月经周期大约持续 28 天，在第 14 天左右排卵。
Fertilisation occurs when a sperm nucleus fuses with an egg nucleus in the fallopian tube, forming a diploid zygote. The zygote implants into the uterus lining and develops into an embryo. The placenta allows exchange of nutrients, gases, and waste between the mother and foetus without mixing their blood.
当精子核在输卵管中与卵子核融合时，发生受精，形成二倍体受精卵。受精卵植入子宫内膜并发育成胚胎。胎盘允许母体与胎儿之间交换营养、气体和废物，而不会混合双方的血液。
Sexual reproduction increases genetic variation, which enhances the survival of a species in changing environments. Asexual reproduction produces identical offspring and is faster, but lacks variation.
有性生殖增加了遗传变异，增强了物种在不断变化环境中的生存能力。无性生殖产生完全相同的后代，速度更快，但缺乏变异。
12. Health and Disease | 健康与疾病
Health is a state of complete physical, mental, and social well-being. Diseases can be communicable (infectious, caused by pathogens) or non-communicable (not transmitted between people, often linked to lifestyle or genetics). Pathogens include bacteria, viruses, fungi, and protists.
健康是一种完全的生理、心理和社会良好状态。疾病可分为传染性（由病原体引起）和非传染性（不在人与人之间传播，通常与生活方式或遗传有关）。病原体包括细菌、病毒、真菌和原生生物。
The body defends itself against pathogens through physical barriers (skin, mucus), chemical defences (stomach acid, lysozyme in tears) and the immune system. White blood cells can engulf pathogens (phagocytosis) and produce antibodies that neutralise specific antigens. Vaccination introduces a harmless form of a pathogen to stimulate antibody production and create memory cells for long-term immunity.
身体通过物理屏障（皮肤、粘液）、化学防御（胃酸、泪液中的溶菌酶）和免疫系统抵御病原体。白细胞能吞噬病原体（吞噬作用）并产生抗体以中和特定抗原。疫苗接种引入无害形式的病原体，刺激抗体产生并产生记忆细胞，以获得长期免疫力。
Antibiotics kill bacteria but are ineffective against viruses. Misuse of antibiotics has led to antibiotic-resistant strains, such as MRSA. A balanced diet, regular exercise, and avoiding smoking and excessive alcohol reduce the risk of many non-communicable diseases, including heart disease and type 2 diabetes.
抗生素能杀死细菌但对病毒无效。滥用抗生素导致了抗药性菌株的出现，如 MRSA。均衡饮食、经常锻炼、不吸烟和避免过量饮酒可降低许多非传染性疾病的风险，包括心脏病和 2 型糖尿病。
Published by TutorHao | Biology Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图