Explain how the method of mark and recapture works to determine population size.

Answer:

Capture a sample of organisms, mark them harmlessly, and release them. After they have had time to mix back into the population, capture a second sample and count how many are marked. Use the proportion of marked organisms in the second sample to estimate the total population: (number marked initially × size of the second sample) ÷ number of marked organisms recaptured.