Select the true statements about epithelial tissues. may serve as a covering for structures may serve as a barrier derived exclusively from the ectoderm can specialize to form glands give rise to blood cells classified according to cell shape classified according to the number of layers of cells that are present

The following statements are true about epithelial tissue;

May serve as a covering for structures

May serve as a barrier

Can specialize to form glands

Classified according to cell shape

Classified according to the number of layers of cells that are present

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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