📚 The Role of Water in Life Activities | 水在生命活动中的作用
Water is the most abundant molecule in living organisms, constituting approximately 60–70% of a typical cell's mass and covering roughly 71% of the Earth's surface. Its remarkable physical and chemical properties, which all originate from its simple molecular structure, make it indispensable for processes such as transport, metabolism, temperature regulation and protection. For CIE A-Level Biology, understanding the link between the structure of water and its diverse roles in organisms is a core objective that regularly appears in both multiple-choice and structured examination questions.
水是生物体中最丰富的分子，约占典型细胞质量的60%-70%，并覆盖地球表面约71%。其非凡的物理和化学性质均源于简单的分子结构，使其在运输、代谢、温度调节和保护等过程中不可或缺。在CIE A-Level生物学中，理解水的结构与其在生物体中多种功能之间的联系是核心学习目标，经常出现在选择题和结构化问答题中。
1. Structure of the Water Molecule | 水分子的结构
A water molecule (H₂O) consists of one oxygen atom joined to two hydrogen atoms by covalent bonds. Oxygen is significantly more electronegative than hydrogen; therefore, the shared electrons in each O–H bond are drawn closer to the oxygen nucleus. This unequal sharing produces a partial negative charge
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