In very extreme weather, the xylem cells are damaged as well. describe how the plant is affected if the xylem unable to function correctly.

Xylem tissue is important is the transport of water and minerals from the roots to the leaves of the plant. It is this water that is used in photosynthesis and also significant in the transpirational pull that significant in plant support. When the xylem is destroyed the plant wilts because it loses turgidity and dies because water is unable to reach the leaves for photosynthesis so the plant cannot make its food.

relative dating involves things like higher layers are most recent than rocks lower in the sequence. this can be extended to the known sequence of fossils. rocks containing rabbit fossils are later than those containing dinosaur fossils.  

absolute dating methods mainly use radioactive elements that have known rates of decay and produce recognizable products. for example potassium 40 decays to produce argon. once a rock has solidified the argon is trapped. by measuring the argon and potassium0 you can get an accurate number for the age.  

some other methods are good for archaeological ages. dendrochronology involves recognizing the sequence of tree rings. the orientation of magnetized particles in baked clay can be used to date a fire.

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