📚 A-Level CCEA Biology: Key Comparisons in the Specification | CCEA生物考纲核心知识点对比
Understanding the CCEA A-Level Biology specification requires students to compare and contrast a wide range of biological processes and structures. This article presents nine essential comparisons that frequently appear in examinations, equipping you with concise yet thorough revision notes.
理解CCEA A-Level生物学考纲要求学生比较和对比广泛的生物学过程与结构。本文呈现了九组考试中常见的关键知识点对比，为你提供简明而全面的复习笔记。
1. Prokaryotic vs Eukaryotic Cells | 原核细胞与真核细胞
Prokaryotic cells typically measure 0.1–5.0 µm in diameter, whereas eukaryotic cells are larger, ranging from 10–100 µm.
原核细胞的直径通常为0.1–5.0 µm，而真核细胞更大，在10–100 µm之间。
Prokaryotes lack a true nucleus; their genetic material is a single, circular DNA molecule located in the nucleoid region and is not enclosed by a membrane. Eukaryotes possess a membrane-bound nucleus containing multiple linear chromosomes associated with histone proteins.
原核生物没有真正的细胞核；其遗传物质是一条环状DNA分子，位于拟核区，没有膜包裹。真核生物具有膜包被的细胞核，其中含有多条与组蛋白结合的线性染色体。
Membrane-bound organelles such as mitochondria, endoplasmic reticulum and Golgi apparatus are absent in prokaryotic cells, but are present in eukaryotes.
原核细胞缺少线粒体、内质网和高尔基体等膜包被的细胞器，而这些细胞器存在于真核细胞中。
Prokaryotic ribosomes are 70S (composed of 50S and 30S subunits), while eukaryotic ribosomes are 80S (composed of 60S and 40S subunits).
原核生物的核糖体为70S（由50S和30S亚基组成），真核生物的核糖体为80S（由60S和40S亚基组成）。
The cell wall of prokaryotes is made of peptidoglycan (murein), whereas plant eukaryote cell walls contain cellulose and fungal walls contain chitin.
原核生物的细胞壁由肽聚糖（胞壁质）组成，而植物真核细胞的细胞壁含有纤维素，真菌细胞壁含有几丁质。
Prokaryotes reproduce asexually through binary fission, while eukaryotes divide by mitosis (and meiosis for gametes).
原核生物通过二分裂进行无性繁殖，而真核生物通过有丝分裂（以及配子的减数分裂）进行分裂。
2. Mitosis vs Meiosis | 有丝分裂与减数分裂
Mitosis produces two genetically identical diploid daughter cells for growth and repair, whereas meiosis generates four genetically non-identical haploid gametes for sexual reproduction.
有丝分裂产生两个遗传上相同的二倍体子细胞，用于生长和修复；而减数分裂产生四个遗传上不同的单倍体配子，用于有性生殖。
Mitosis involves a single round of nuclear division, while meiosis consists of two successive divisions: meiosis I (reductional) and meiosis II (equational).
有丝分裂只包含一次核分裂，而减数分裂包括两次连续的分裂：减数第一次分裂（减数分裂）和减数第二次分裂（均等分裂）。
In mitosis, homologous chromosomes do not pair up; in meiosis, homologous chromosomes synapse during prophase I, forming bivalents, and crossing over occurs, leading to genetic variation.
在有丝分裂中，同源染色体不配对；在减数分裂中，同源染色体在前期I联会，形成二价体，并发生交叉互换，导致遗传变异。
Mitosis maintains the same chromosome number as the parent cell (2n → 2n), while meiosis halves the chromosome number (2n → n).
有丝分裂维持与亲代细胞相同的染色体数目(2n → 2n)，而减数分裂将染色体数目减半(2n → n)。
Independent assortment of homologous chromosomes in metaphase I of meiosis further contributes to genetic diversity, a process absent from mitosis.
减数分裂中期I中同源染色体的独立分配进一步促进了遗传多样性，这一过程在有丝分裂中不存在。
3. Light-Dependent vs Light-Independent Reactions | 光反应与暗反应（卡尔文循环）
Light-dependent reactions occur on the thylakoid membranes of chloroplasts and require light energy to split water (photolysis), producing ATP, reduced NADP and oxygen.
光反应发生在叶绿体的类囊体薄膜上，需要光能来裂解水（光解），产生ATP、还原型NADP和氧气。
The Calvin cycle (light-independent reactions) takes place in the stroma and uses ATP and reduced NADP from the light-dependent stage to fix CO₂ and synthesise triose phosphate, which can form glucose.
卡尔文循环（不依赖光的反应）发生在基质中，利用光反应阶段产生的ATP和还原型NADP来固定CO₂，合成磷酸丙糖，进而可生成葡萄糖。
Light energy drives the excitation of electrons in chlorophyll, leading to cyclic and non-cyclic photophosphorylation; the Calvin cycle is enzyme-driven and does not directly require light, although it is indirectly light-dependent.
光能驱动叶绿素中电子的激发，导致环式和非环式光合磷酸化；卡尔文循环由酶驱动，不直接需要光，尽管它间接依赖光。
The main products of the light-dependent reactions are ATP, reduced NADP and O₂; the Calvin cycle consumes CO₂ and regenerates RuBP, generating carbohydrate intermediates.
光反应的主要产物是ATP、还原型NADP和O₂；卡尔文循环消耗CO₂并再生RuBP，生成碳水化合物中间产物。
In the CCEA specification, students should know that the enzyme RuBisCO catalyses carbon fixation in the Calvin cycle, and that the rate of light-independent reactions can be influenced by temperature and CO₂ concentration.
在CCEA考纲中，学生应知道RuBisCO酶催化卡尔文循环中的碳固定，并且暗反应的速率可能受温度和CO₂浓度的影响。
4. Aerobic vs Anaerobic Respiration | 有氧呼吸与无氧呼吸
Aerobic respiration takes place in the mitochondria (matrix and cristae) and requires oxygen as the final electron acceptor in the electron transport chain. Anaerobic respiration occurs solely in the cytoplasm and does not use oxygen.
有氧呼吸发生在线粒体（基质和嵴）中，需要氧气作为电子传递链的最终电子受体。无氧呼吸仅在细胞质中进行，不使用氧气。
Aerobic respiration yields approximately 32–34 ATP molecules per glucose, while anaerobic respiration produces only 2 ATP per glucose (via substrate-level phosphorylation in glycolysis).
有氧呼吸每个葡萄糖分子约产生32–34个ATP，而无氧呼吸每个葡萄糖仅产生2个ATP（通过糖酵解的底物水平磷酸化）。
In animals, anaerobic respiration produces lactate (lactic acid), whereas in
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