📚 Photosynthesis and the Leaf | 光合作用与叶片
Photosynthesis is the biological process in which green plants, algae and some bacteria capture light energy and convert it into chemical energy stored in glucose. Carbon dioxide and water are the raw materials, and oxygen is released as a by-product. In IGCSE Biology, a clear understanding of the equation, the leaf structure and the factors that control the rate is essential.
光合作用是绿色植物、藻类和某些细菌捕获光能并将其转化为储存在葡萄糖中的化学能的生物过程。二氧化碳和水是原料，氧气作为副产物释放。在 IGCSE 生物中，清晰理解方程式、叶片结构以及控制速率的因素至关重要。
1. The Word Equation and Chemical Equation | 文字方程式与化学方程式
The word equation for photosynthesis is:
光合作用的文字方程式是：
carbon dioxide + water → glucose + oxygen
二氧化碳 + 水 → 葡萄糖 + 氧气
The chemical equation is balanced to show that six molecules of carbon dioxide and six molecules of water produce one molecule of glucose and six molecules of oxygen. Light energy and chlorophyll are required for this change to happen.
化学方程式经过配平，表明六个二氧化碳分子和六个水分子生成一个葡萄糖分子和六个氧分子。光能和叶绿素是发生这一变化所必需的。
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
The glucose produced can be used immediately for respiration, or converted into insoluble starch for storage. It can also be changed into sucrose for transport, or used to make cellulose, proteins and fats.
产生的葡萄糖可立即用于呼吸作用，或转化为不溶性淀粉进行储存。它还可以转化为蔗糖用于运输，或用于制造纤维素、蛋白质和脂肪。
2. The Role of Light, Chlorophyll and Temperature | 光、叶绿素与温度的作用
Light provides the energy that drives photosynthesis. Chlorophyll, the green pigment located in chloroplasts, captures light energy and uses it to split water molecules. Without light, photosynthesis cannot occur.
光为光合作用提供能量。叶绿素是位于叶绿体中的绿色色素，它捕获光能并利用其分解水分子。没有光，光合作用就无法发生。
Chlorophyll absorbs light most strongly in the blue and red regions of the visible spectrum. Green light is reflected, which is why leaves appear green. The pigment molecules are found in the thylakoid membranes inside chloroplasts.
叶绿素在可见光谱的蓝光和红光区域吸收光最强。绿光被反射，因此叶片呈现绿色。色素分子位于叶绿体内部的类囊体膜上。
Temperature affects the speed of the enzyme-controlled reactions of photosynthesis. At low temperatures, the enzymes work slowly; at very high temperatures, they become denatured and the rate falls sharply.
温度影响光合作用酶促反应的速度。在低温下，酶工作缓慢；在高温下，酶会变性，速率急剧下降。
3. Leaf Structure: A Factory for Photosynthesis | 叶片结构：光合作用的工厂
The leaf is adapted so that each part contributes to efficient photosynthesis. Its broad, flat blade provides a large surface area for capturing sunlight and allowing carbon dioxide to diffuse in quickly.
叶片经过适应，使每个部分都为高效光合作用作出贡献。其宽大而扁平的叶片提供了巨大的表面积，用于捕获阳光并让二氧化碳快速扩散进入。
Leaves are also thin, which minimises the diffusion distance for gases such as carbon dioxide and oxygen. This allows the mesophyll cells to receive a continuous supply of reactants and to release products efficiently.
叶片也很薄，这使二氧化碳和氧气等气体的扩散距离最小化。这使得叶肉细胞能持续获得反应物并高效释放产物。
Inside the leaf
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