Date Name Period Perry Sampling Methods to Study Populations How can .0 estimate the size of a population of organisms from a sample? !tat 1. You estimated the number of mice in this grid. Before you actually count them, how many did you estimate? do Tyr 1 3. Estimate the total number of mice by multiplying the number of mice in the top left square by the number of total squares? Wth 2. Now count ONLY the number in the top left square. How many did you actually count? 121 t1-41/e i 4. Repeat steps 2 & 3 above for the bottom left square: Count = - t, Total population from this sample = 1 0 5. Repeat steps 2 & 3 above for the bottom square, 2nd from the left: Count = V.:, Total population from this sample = ; 6. Find the average of your samples by adding your total population from 3, 4 and 5 above and ÷ 3 Average population size = 7. Now count the entire population? 8. Compare the actual number of mice to each of your samples and the average of the samples: 51( The estimation activity above is an exercise in random sampling. This is a useful tool to study populations when you cannot count the ENTIRE population. You can obtain estimates about a population size by using the random sampling and averaging method! 9. What is a census study? 3t: 1.A:Les ali .dirvteAmitudi 10. Could a census study be used in the mouse example above? foe Explain why or why not: Li2—% 11. Define the following: a. Random sampling: b. Bias in sampling: c. Sampling error: (provide a specific example) vn tiv\00-u‘ VVN 1/11. 1 5C(gudv3fr 12. List four factors that can affect a population's size: ctert.,41.— N.ce (v..(4,4crt Created by T Harbin toi 5 This grid represents a meadow measuring 10 m on each side. Each grid segment is 1m X 1m. Each black dot represents one sunflower plant. B • G I 15. If you were to walk this meadow in the following segments, how many sunflowers would you estimate would be in the entire meadow? 2.1 3 D4= 300 \ j2, G8 = 100 100 •• 6 • ••• ; • • • a • r • • • ilk O. • • :i •• • ID • • 0 •g•O• ••• • • •i• • • 111 • •• n K Average the 3 samples above? 17. Count the entire sunflower population? 18. Compare the actual number of sunflowers to each sample and the average of those samples: 61( ' Li • g 19. Why do biologists use sampling methods? all aectsc.tfia 20. Population Sampling is usually more effective when the population has an even dispersion pattern. Clumped dispersion patterns are the least effective. Explain why this would be the case. 21. Describe how you would use Sampling to determine the population of dandelions in your yard. ciitumm 22. In a forest that measures 5 miles by 5 miles, a sample was tak _ n to count the number of silver maple trees in the forest. The number of trees counted in the grid is shown below. I he grids where the survey was taken were chosen randomly. Determine how many silver maple trees are in this forest using the random sampling technique. Show your work! 7 10 ti41 4111_ • F j„0 J2= • •• 14. Why are F1 & 66(not good choices for the question above? r) / • .1 • ♦ 13. If you were going to estimate how many sunflowers were in this meadow, which grid would be the best to sample? Provide the letter and number • • a see • ! se •• e di 9 if •• •

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