Cambridge Lower Secondary Complete Biology SB 2nd: Exam-style Practice | 生物：Cambridge Lower Secondary Complete Biology SB 2nd 真题精练

📚 Cambridge Lower Secondary Complete Biology SB 2nd: Exam-style Practice | 生物：Cambridge Lower Secondary Complete Biology SB 2nd 真题精练

Mastering Cambridge Lower Secondary Biology requires more than memorising facts — it calls for applying knowledge to exam-style challenges. This article brings together carefully crafted questions directly aligned with the second edition of the Complete Biology Student Book. Each topic is reinforced with a bilingual question and detailed explanation, helping you refine your reasoning and achieve top marks in assessments.

掌握剑桥初中生物学不仅需要记忆知识点，更需要将所学应用于真题情境中。本文汇集了与第二版《Complete Biology Student Book》精准匹配的典型题目。每个专题都配有双语问题与详细解析，帮助你锤炼解题思维，在考试中斩获高分。

1. Characteristics of Living Things and Classification | 生物的共同特征与分类

Question: A student observes an organism. It has cell walls made of chitin, stores carbohydrates as glycogen, and feeds by extracellular digestion of dead matter. To which kingdom does it belong? A. Animalia B. Plantae C. Fungi D. Prokaryotae

问题：一学生观察某生物，其细胞壁由几丁质组成，以糖原储存碳水化合物，并通过胞外消化死亡有机质获取营养。它属于哪个界？A. 动物界 B. 植物界 C. 真菌界 D. 原核生物界

Answer and Explanation: C. Fungi. The kingdom Fungi is characterised by chitinous cell walls, glycogen as a storage carbohydrate, and saprotrophic nutrition — absorbing nutrients after extracellular digestion of dead or decaying matter. Animals lack cell walls, plants have cellulose cell walls and store starch, and most prokaryotes have peptidoglycan cell walls, if present. Additionally, the MRS GREN acronym (Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition) applies to all living organisms, but these specific features are diagnostic for Fungi in classification questions.

答案与解析：C。真菌界以几丁质细胞壁、糖原作为储存多糖以及腐生营养为特征——通过胞外消化死亡或腐烂有机物后吸收营养。动物没有细胞壁，植物细胞壁由纤维素组成并储存淀粉，原核生物若有细胞壁通常由肽聚糖构成。此外，所有生物都符合MRS GREN（运动、呼吸作用、应激性、生长、生殖、排泄、营养）生命特征，但在分类题目中，题干给出的具体性状正是真菌界的标志。

2. Cell Structure and Specialisation | 细胞结构与特化

Question: Which of the following is a specialised plant cell with a spiral thickening of lignin that allows it to withstand pressure changes during water transport? A. Root hair cell B. Xylem vessel element C. Phloem sieve tube element D. Palisade mesophyll cell

问题：下列哪种特化植物细胞具有螺旋状木质素加厚，使其能够承受水运输中的压力变化？A. 根毛细胞 B. 木质部导管分子 C. 韧皮部筛管分子 D. 栅栏叶肉细胞

Answer: B. Xylem vessel elements are dead, hollow cells with lignin deposited in rings, spirals, or pitted patterns. This lignification prevents collapse under negative pressure (tension) and provides structural support. Root hair cells absorb water and minerals, phloem sieve tubes transport organic nutrients, and palisade cells carry out photosynthesis.

答案：B。木质部导管分子是死细胞，中空，并具有环纹、螺旋纹或孔纹的木质素沉积。这种木质化防止了细胞在负压（拉力）下塌陷，并提供结构支撑。根毛细胞吸收水和矿物质，韧皮部筛管运输有机物，栅栏细胞进行光合作用。

3. Movement of Substances: Diffusion and Osmosis | 物质的运动：扩散与渗透

Question: A plant cell is placed in a concentrated sucrose solution. Its cytoplasm shrinks and the plasma membrane pulls away from the cell wall. Which process has occurred? A. Active transport B. Plasmolysis C. Turgor pressure increase D. Endocytosis

问题：将一个植物细胞放入浓蔗糖溶液中，细胞质收缩，质膜与细胞壁分离。发生了哪种过程？A. 主动运输 B. 质壁分离 C. 膨压增大 D. 胞吞作用

Answer: B. Plasmolysis occurs when a plant cell loses water by osmosis to a hypertonic external solution. The water potential inside the cell is higher than outside, so water moves out, causing the vacuole to shrink and the plasma membrane to detach from the rigid cell wall. Active transport requires energy and moves substances against the concentration gradient, not water. Turgor pressure results from water entry, not loss.

答案：B。当植物细胞通过渗透作用将水分丧失到高渗外部溶液时，即发生

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