Unformatted text preview: small amounts.
• Carbon and oxygen are obtained from the air. The rest of the required nutrients are from water and minerals
dissolved in the water.
• Microbes in the soil form symbiotic relationships with root cells which benefit plants by helping them acquire
• Fungal mycorrhizae help plants absorb minerals, especially phosphorous.
• Nitrogen-fixing bacteria convert nitrogen compounds into forms that plants can absorb.
• Transpiration (water transport) involves three processes: absorption at the roots, capillary action in the
xylem, and evaporation at the leaves.
• Roots acquire dissolved minerals in a four-step process:
• Active transport into the root hairs, which moves minerals against their concentration gradient.
• Diffusion through the cortex cells and into the pericycle.
• Active transport out of the pericycle cells and into the vascular cylinder.
• Diffusion into the xylem.
• Capillary action, which draws water up the xylem vessels.
• Cohesion: water mo...
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- Winter '09