What are the four factors demographers look at to determine population size

Sampling

- counting the number of organisms in a small area and multiplying to estimate the number in a larger area

Mark & Recapture

- capture an organism & release it to remix with population. Then recapture some more in that area to determine population size. Formula is as follows: R (marked recaptures) / C (total in second sample) = M (marked initially) / N (total pop. size)

Indirect Observation -

estimating the population size by tracks, nest or other animal signs in an ecosystem.

what statement best describes the difference between the sympathetic and parasympathetic nervous systems?

the sympathetic nervous system prepares the body for intense physical activity and is often referred to as the fight-or-flight response. the parasympathetic nervous system has almost the exact opposite effect and relaxes the body and inhibits or slows many high energy functions.