The Building Blocks of Life | 生命的基本构建块

📚 The Building Blocks of Life | 生命的基本构建块

All living organisms are composed of a small set of chemical elements that assemble into an astonishing variety of molecules and structures. In Cambridge A-Level Biology, understanding these building blocks means linking atoms, biological molecules, organelles and cells into one coherent picture of life.

所有生物体都由少数化学元素组成，这些元素组装成种类繁多的分子和结构。在剑桥 A-Level 生物中，理解这些基本构建块意味着将原子、生物分子、细胞器和细胞联系成一幅连贯的生命图景。

1. From Atoms to Biological Molecules | 从原子到生物分子

The most abundant elements in living organisms are carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur. Carbon is especially important because each carbon atom can form four covalent bonds, allowing the construction of long chains, branched structures and rings.

生物体中最丰富的元素是碳、氢、氧、氮、磷和硫。碳尤其重要，因为每个碳原子可以形成四个共价键，从而能够构建长链、支链结构和环状结构。

Small organic subunits called monomers join together by condensation reactions, in which a water molecule is removed. The reverse process, hydrolysis, adds water to split a polymer back into monomers.

称为单体的小有机亚基通过缩合反应连接在一起，反应中脱去一分子水。相反的过程——水解——则加入水将聚合物分解回单体。

monomer + monomer → polymer + H₂O

2. Water: The Medium of Life | 水：生命的介质

Water is a polar molecule because oxygen attracts the shared electrons more strongly than hydrogen. This polarity allows hydrogen bonds to form between water molecules, giving water high cohesion, adhesion and surface tension.

水是一种极性分子，因为氧对共用电子的吸引比氢更强。这种极性使水分子之间形成氢键，赋予水较高的内聚力、附着力和表面张力。

Water has a high specific heat capacity and a high latent heat of vaporisation, so it stabilises temperatures in organisms and cools the body through evaporation of sweat. It is also an excellent solvent for ions and polar molecules, enabling transport and metabolic reactions.

水具有较高的比热容和较高的汽化潜热，因此能够稳定生物体内的温度，并通过汗液蒸发使身体降温。它也是离子和极性分子的优良溶剂，使运输和代谢反应得以进行。

Ice is less dense than liquid water because hydrogen bonds hold water molecules in an open lattice, so ice floats and insulates aquatic habitats.

冰的密度低于液态水，因为氢键使

Published by TutorHao | A-Level Biology Revision Series | aleveler.com

更多咨询请联系16621398022（同微信）