Cognitive
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Synthesis / Modelling |
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Cognitive (knowledge-based) activities
Jean-Michel Filion peering into the center of a healthy, yet hollow, black cherry tree. The woody (xylem) cells inside the tree die and it is their subsequent rigidity that supports the tree vertically. Over time the very old xylem cells may degenerate and turn to powder, producing a hollow, yet still living giant tree. The outer, living cells, just under the bark are called phloem cells. |