In yeast cells, the process that occurs when there is not enough oxygen for aerobic respiration is called

Fermentation is the pathway taken at the end of glycolysis when oxygen is not present.  In yeast cells, the fermentation process produces carbon dioxide, alcohol, NAD+ (which then returns to kickstart glycolysis), but no ATP.  The process of fermentation is used in the production of various food products, including breads.  Carbon dioxide released from the process of fermentation causes bread dough to rise.

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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