Photosynthesis | 光合作用

📚 Photosynthesis | 光合作用

Photosynthesis is a vital chemical process by which phototrophs (green plants, algae and some bacteria) use light energy to convert carbon dioxide and water into glucose and oxygen. This process is the foundation of all ecosystems, because it produces chemical energy that flows through food chains and releases oxygen that most organisms need to respire.

光合作用是光养生物（绿色植物、藻类和某些细菌）利用光能将二氧化碳和水转化为葡萄糖和氧气的重要化学生理过程。这一过程是所有生态系统的基础，因为它产生了沿食物链流动的化学能，并释放出大多数生物进行呼吸所需的氧气。

1. Why Photosynthesis Matters | 光合作用为什么重要

Photosynthesis is essential for life on Earth for several key reasons. First, it is the only major biological pathway that captures light energy and converts it into chemical energy in the form of glucose. This glucose is then used as a fuel for respiration or converted into starch, cellulose and other organic molecules.

光合作用对地球生命至关重要，原因有几点。首先，它是唯一能够捕获光能并将其转化为葡萄糖形式化学能的主要生物代谢途径。得到的葡萄糖随后被用作呼吸作用的燃料，或转化为淀粉、纤维素和其他有机分子。

Second, photosynthesis maintains atmospheric oxygen levels. As plants produce oxygen as a by-product, the oxygen concentration in the atmosphere remains suitable for aerobic respiration and for the ozone layer that shields life from ultraviolet radiation.

其次，光合作用维持大气中的氧气含量。植物作为副产物释放氧气，使大气中的氧气浓度保持在适合有氧呼吸的水平，并支持臭氧层，保护生命免受紫外线辐射。

Third, through food chains, herbivores depend on plant biomass for energy and nutrients, and carnivores depend on herbivores, so photosynthesis ultimately supports almost all consumers, decomposers and even microorganisms in ecosystems.

第三，通过食物链，草食动物依赖植物生物量获取能量和营养，肉食动物依赖草食动物，因此光合作用最终支持生态系统中几乎所有消费者、分解者甚至微生物。

2. The Balanced Equations | 光合作用的化学方程式

Photosynthesis can be summarised by a balanced word equation and a chemical equation. The process requires six molecules of carbon dioxide and six molecules of water, which react in the presence of light energy and chlorophyll to form one molecule of glucose and six molecules of oxygen.

光合作用可以用配平的文字方程式和化学方程式来概括。该过程需要六个二氧化碳分子和六个水分子，在光能和叶绿素的存在下反应生成一个葡萄糖分子和六个氧分子。

Word equation:

文字方程式：

carbon dioxide + water → glucose + oxygen

Symbol equation:

符号方程式：

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Notice that this overall equation is a simplified summary: in plants, glucose is often converted to starch for storage or used to build cellulose and proteins. The light energy required is usually supplied as sunlight and absorbed by the pigment chlorophyll.

注意，这个总方程式是一个简化总结：在植物中，葡萄糖通常被转化为淀粉储存，或者用于构建纤维素和蛋白质。所需的光能通常以阳光形式提供

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