Exam 3 Notes

Cationexchangeisaprocessthat contributestotheiruptake

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Unformatted text preview: the growing season) Loading Sucrose into Phloem Proton pumping and co­transport of sucrose allows companion cells to accumulate sugar at high concentrations 29 Pressure Flow: The Translocation Mechanism o High pressure at source o Low pressure at sink o Pressure gradient drives flow of phloem sap from source to sink o Sugar is loaded into sieve tube, which lowers he water potential, water follows by osmosis o Water uptake causes positive pressure o Unloading of sugar at the sink reduces pressure Chapter 37: Soil and Plant Nutrition Concept 37.1: Soil contains a living complex ecosystem In addition to climate, texture and composition of soil are major factors determining the distribution of plants Texture and Composition of Soils Soil is made up of particles derived from the breakdown of rocks (minerals) along with organic material (humus) Texture ­ the relative amounts of various sizes of soil particle Composition ­ relative amounts of inorganic and organic components Soil Horizons o Figure 37.2 30 o Soil horizons are visible in vertical profile o “A” horizon is a mix of humus and minerals Humus consists of decomposing organic material...
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