Photosynthesis and Plant Nutrition | 光合作用与植物营养

📚 Photosynthesis and Plant Nutrition | 光合作用与植物营养

Photosynthesis is the process by which green plants use light energy to convert carbon dioxide and water into glucose and oxygen. It is the foundation of nearly every ecosystem, because it supplies food for herbivores, carnivores and decomposers, and it also maintains the oxygen level in the atmosphere.

光合作用是绿色植物利用光能将二氧化碳和水转化为葡萄糖和氧气的过程。它几乎是所有生态系统的基础，因为它为食草动物、食肉动物和分解者提供了食物，同时维持了大气中的氧气含量。

1. What Is Photosynthesis? | 什么是光合作用

The overall reaction can be written as a word equation or a chemical equation. In the word equation, the reactants are carbon dioxide and water, and the products are glucose and oxygen.

光合作用的总反应可以用文字方程式或化学方程式表示。在文字方程式中，反应物是二氧化碳和水，产物是葡萄糖和氧气。

carbon dioxide + water → glucose + oxygen

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Light energy is absorbed by the green pigment chlorophyll, which is found in chloroplasts. This energy is used to join carbon dioxide and water together to make glucose.

叶绿体中的绿色色素叶绿素吸收光能，并利用这些能量将二氧化碳和水合成葡萄糖。

2. Why Leaves Are Efficient for Photosynthesis | 叶片为什么有利于光合作用

Leaves are broad and thin, which gives a large surface area for absorbing sunlight and a short diffusion path for gases such as carbon dioxide and oxygen.

叶片宽而薄，可以接受更多阳光，同时气体（如二氧化碳和氧气）的扩散距离较短。

The upper epidermis is transparent, allowing light to pass through to the palisade mesophyll. Palisade cells are packed with chloroplasts and are positioned close to the top surface, so they receive the most light.

上表皮透明，可以让光线透过到达栅栏组织。栅栏细胞含有大量叶绿体，并且靠近叶片上表面，因此能接受最多的光照。

The spongy mesophyll contains air spaces that allow carbon dioxide and oxygen to diffuse easily between the leaf and the atmosphere. Stomata in the lower epidermis control gas exchange and water loss.

海绵组织中存在细胞间隙，便于二氧化碳和氧气在叶片与大气之间扩散。下表皮上的气孔调节气体交换和水分散失。