BIO-0014 Lecture 15: Phloem and Xylem interaction
9 Mar 2017
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Movement of sugars through trees in phloem, sugar loading. Loads it up at the leaves due to calvin cycle: requires atp, moves down through the phloem. Source = leaves, under higher pressure: sugar unloading, down at the roots, requires atp roots = sinks, under lower pressure, munch hypothesis, cyanide had no effect, thus no atp necessary for transportation, only blocks atp synthesis. If you block oxygen, the cells in the trunk would still be able to transport: only affects atp synthesis. If you give it a low temperature, transportation is also still able to work: only hurts mitochondrial production of atp. Animals eat the bark since it"s high in sugar. Especially in the winter/snow: once an entire layer of bark is gone, it"s called a girdle, plant will die, sugars can"t travel. If you girdle at 1, the tree will die. If you girdle at 2, will kill mango.
