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Structure of the leaf and its adaptation for photosynthesis

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Introduction

Structure of the leaf and its adaptation for photosynthesis The leaf is the organ of a plant in which photosynthesis occurs. For photosynthesis to occur, the chlorophyll, mostly found in leaves, must absorb light energy and transform it into chemical energy used in the synthesis of carbohydrates from water and carbon dioxide. Therefore, the leaf has many adaptations for photosynthesis. Firstly, the structure of a leaf is optimized for absorbing light and carrying out photosynthesis. A typical leaf consists of a lamina, petiole and a leaf stalk. The lamina of a leaf has a large flat surface area with chlorophyll located close to the top surface, for maximum light absorption. The petiole holds the lamina away from the stem so that the lamina can obtain sufficient sunlight and air. ...read more.

Middle

When water pressure is high, the thin outer walls of the cells are forced into a curved shape. This pulls the think inner walls of the guard cells away from one another, opening the stoma. When water pressure decreases, the inner walls pull together and the stoma closes. Guard cells respond to conditions in the environment, such as wind and temperature, helping to maintain homeostasis within a leaf. Leaves are covered on the top and bottom by epidermis made of a layer of tough, irregularly shaped cells. The epidermis of many leaves is also covered by the cuticle and lack chloroplast. Together, the epidermis and the cuticle form a waterproof barrier that protects tissues, limits the loss of water through evaporation and help focus the light onto the mesophyll layers, right below the upper epidermis. ...read more.

Conclusion

This also means that water evaporates from these surfaces and is lost to the atmosphere, a process called transpiration. The water would be replaced by water drawn into the leaf through xylem vessels in the vascular tissue. The vascular tissue of leaves are connected directly to the vascular tissues of stems, making them part of the plant's transport system. In leaves, xylem and phloem tissues are gathered together into bundles that run from the stem into the petiole and end among the mesophyll cells. The xylem brings water and dissolved mineral salts to the leaf from the soil via the roots and the stem. Once out of the veins, these raw materials diffuse from cell to cell right through the mesophyll of the leaf. Once the chlorophyll receives the essential raw materials, the manufactured food such as glucose made would then be transported as sucrose via the phloem to all the plant cells. ...read more.

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