2.
What effect do enzymes have on chemical reactions?

Enzymes are needed to speed up chemical reactions in organisms. They work by lowering the activation energy of reactions.

Enzymes position substrates into active sites.

Various conditions affect enzyme function. Pepsin and trypsin are two digestive enzymes that work in contrasting environments.

Explanation:

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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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