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Elementary Science Education

Relationship between photosynthesis and whole plants

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      Bernard Nebel
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      A plant has no skeleton. Instead, the cells themselves stacked beside and on top of one another provide the plant’s shape and structure. The key thing that enables this “stacking”, without collapsing into a blob, is the more or less rigid wall of each cell, (each cell’s cell wall). Examination of the cell wall with an electron microscope shows it to be a mat of fibrils. Type into your browser: cell wall mat of cellulose fibrils images

      Each fibril in the cell wall, seen in photomicrograph above, is comprise of numerous parallel cellulose molecules (with other materials in the matrix). Type into your browser: Arrangement of Fibrils, Microfibrils, and cellulose in cell walls (click on diagram)

      Review the molecular structure of glucose, the major product of photosynthesis. (Type into your browser: molecular structure glucose) Ask students of find the similarity between glucose and cellulose. They should readily note that cellulose molecules are chains of glucose molecules boned together (with the removal of an H and OH). Hence, they should note the relatively straight path:

      Photosynthesis–>carbon dioxide and water –>glucose –> cellulose –> cell walls –> plant growth.

      Similarly, a plant is able to make proteins, lipids, vitamins, and all other constituents form glucose and a few other elements, e.g. N, P, K, absorbed from the soil.

      The big mystery remaining is how this process is intricately controlled to lay down cellulose in the specific pattern to required to form a given cell–one of the many types in making up plant parts. See below.

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