Why does a person heart rate fluctuate as a person activity level changes?

An individual's heart rate is changed or gets fluctuated due to his or her change in physical activities. This is due to the fact that with an enhancement in the physical activity, the demand for oxygen in the blood and in the body upsurges. As more energy is discharged, thus, more oxygen is required. In order to provide more oxygen to the blood, the heart is required to pump more blood in and out, which results in an increase in the heart rate.

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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name and explain one of the event that occurs during meiosis that increases the variation in offspring even more than simple reproduction?