📚 Photosynthesis | 光合作用
Photosynthesis is the process by which green plants, algae and some bacteria convert light energy into chemical energy stored in glucose. It is one of the most important biochemical pathways on Earth, providing the oxygen we breathe and the food we eat.
光合作用是绿色植物、藻类和某些细菌将光能转化为储存在葡萄糖中的化学能的过程。它是地球上最重要的生化途径之一，提供了我们呼吸的氧气和食用的食物。
1. The Word Equation | 文字方程式
ion: carbon dioxide + water → glucose + oxygen (in the presence of light and chlorophyll).
光合作用可以用文字方程式概括：二氧化碳 + 水 → 葡萄糖 + 氧气（在光照和叶绿素存在下）。
carbon dioxide + water → glucose + oxygen
二氧化碳 + 水 → 葡萄糖 + 氧气
2. Chemical Equation | 化学方程式
The balanced chemical equation shows the exact proportion of reactants and products. Six molecules of carbon dioxide combine with six molecules of water to form one molecule of glucose and six molecules of oxygen.
平衡化学方程式显示了反应物和产物的精确比例。六个二氧化碳分子与六个水分子结合生成一个葡萄糖分子和六个氧分子。
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
3. The Role of Chlorophyll | 叶绿素的作用
Chlorophyll is a green pigment located in chloroplasts. It absorbs light energy, mainly in the red and blue parts of the spectrum, and uses it to drive the light-dependent reactions of photosynthesis.
叶绿素是位于叶绿体中的绿色色素。它吸收光能，主要是光谱中的红光和蓝光部分，并利用光能驱动光合作用的光反应。
4. Raw Materials and Products | 原料与产物
- Raw materials: carbon dioxide (from the atmosphere) and water (absorbed by roots).
- 原料：二氧化碳（来自大气）和水（由根部吸收）。
- Products: glucose (used for respiration, storage or building cellulose) and oxygen (released as a by-product).
- 产物：葡萄糖（用于呼吸、储存或构建纤维素）和氧气（作为副产品释放）。
5. Light Intensity and Photosynthesis Rate | 光照强度与光合作用速率
As light intensity increases, the rate of photosynthesis rises until another factor becomes limiting. Beyond that point, further increases in light intensity no longer increase the rate.
随着光照强度增加，光合作用速率上升，直到另一个因素成为限制因素。超过该点后，进一步增加光照强度不再提高速率。
6. Carbon Dioxide Concentration | 二氧化碳浓度
Similarly, increasing carbon dioxide concentration up to a certain level boosts the rate of photosynthesis. At high concentrations, the rate levels off because light or temperature is now the limiting factor.
类似地，将二氧化碳浓度增加到一定水平会提高光合作用速率。在高浓度下，速率趋于平稳，因为光照或温度现在是限制因素。
7. Temperature Effects | 温度的影响
Temperature affects the enzymes involved in photosynthesis. The rate increases with temperature up to the optimum (around 35–40°C for most plants). Above this, enzymes denature and the rate falls rapidly.
温度影响参与光合作用的酶。在达到最适温度（大多数植物约35–40°C）之前，速率随温度升高而增加。超过该温度，酶变性，速率迅速下降。
8. Limiting Factors | 限制因素
When a process is limited by the factor present in the least supply, that factor is called the limiting factor. In photosynthesis, light, CO₂ and temperature are the three main limiting factors.
当一个过程受到供应最少的因素限制时，该因素称为限制因素。在光合作用中，光照、二氧化碳和温度是三个主要限制因素。
9. Experiments to Measure Photosynthesis | 测定光合作用的实验
A common experiment uses pondweed in a test tube with water. As the plant photosynthesises, bubbles of oxygen are released. Counting bubbles per minute or collecting the gas in a graduated tube gives a measure of the rate.
一个常见实验使用试管中的水蕴草。当植物进行光合作用时，会释放出氧气气泡。计算每分钟气泡数或收集气体到刻度管中，可以测定速率。
10. Light and Dark Reactions | 光反应与暗反应
Photosynthesis consists of two stages: the light-dependent reactions (which occur in the thylakoid membranes and produce ATP and NADPH) and the light-independent reactions (the Calvin cycle, which uses ATP and NADPH to fix CO₂ into glucose).
光合作用包括两个阶段：光反应（在类囊体膜上发生，产生ATP和NADPH）和暗反应（卡尔文循环，利用ATP和NADPH将CO₂固定为葡萄糖）。
11. Importance of Photosynthesis | 光合作用的重要性
Photosynthesis provides food for nearly all life on Earth, releases oxygen into the atmosphere, and is the basis of the carbon cycle. It also acts as the source of fossil fuels formed over millions of years.
光合作用为地球上几乎所有生命提供食物，向大气释放氧气，并且是碳循环的基础。它也是数百万年来形成的化石燃料的来源。
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