1. 5 Week Assessment Review
IB Seniors – 2nd Year
Topics 1 (statistics) & 5.1 (communities and ecosystems)

2. Guidelines Work in a group of 3-4
Choose a recorder – this is the person responsible for writing down your answers
Groups will be answering questions simultaneously
1 minute per question
We’ll go over answers at the end

3. 1. What is standard deviation used for?

4. 2. What is the advantage of using standard deviation to analyze experimental data?

5. 3. What causes a high standard deviation?

6. 4. What is an error bar?

7. 5. An error bar is a graphical representation of …

8. 6. What is a t-test used for?

9. 7. When using the t-test, what is the level of confidence that is considered a significant difference when comparing two sets of data?

10. 8. When using the t-test to compare two sets of data, the p-value of the data according to the t-table is What does this tell us about the probability of chance?

11. 9. When comparing the height of pine trees in two difference forests, 32 trees were measured in each forest. The value of t was found to be How confident are we that the difference in height is a significant difference?

12. 10. What is the relationship between cause and correlation?

13. 11. Define population.

14. 12. Define community.

15. 13. What are the two components of an ecosystem?

16. 14. Compare autotroph and heterotroph.

17. 15. Compare saprotroph and detritivore.

18. 16. Based on the diagram, how would you describe the role of species X?

19. 17. Based on the food web, which trophic level/levels does species 2 function?

20. 18. What is the initial source of energy for all terrestrial communities?

21. 19. Draw a diagram (to scale) that shows the flow of energy through a community with three trophic levels.

22. 20. If 5,000,000 kJ m-2yr-1 is available from producers in an ecosystem, how much energy is usually available to the tertiary consumer?

23. Answers … Give yourself a point for each correct response

24. 1. SD is used to summarize the spread of values around the mean

25. 2. The dispersal of data around the mean can be measured.

26. 3. A wide range of data points

27. 4. A graphical representation of the variability of data.

28. 5. An error bar is a graphical representation of standard deviation.

29. 6. A t-test is used for deducing the significant difference between two sets of data.

30. 7. 95%

31. 8. There is a 5% probability that chance alone can produce the difference seen.

32. 9. Degrees of freedom are 62 and we are 95% confident that the difference is significant.

33. 10. A correlation does not establish cause; correlation = observation; cause = data/experimentation

34. 11. Population: individuals belonging to the same species in a certain area.

35. 12. Community: A group of populations living and interacting in the same area.

36. 13. Ecosystem: Community & abiotic environment

37. 14. Autotroph: self-feeder; produces its own food from sunlight or chemicals (producer) Heterotroph: relies on other organisms for energy (consumer)

38. 15. Saprotroph: externally digests dead organic matter and then absorbs the nutrients (secretes enzymes) Detritivore: Eats dead/decaying organic matter

39. 16. heterotroph, primary consumer, and secondary consumer

40. 17. 2nd & 3rd consumer

41. 18. Sunlight!

42. 19.

43. 20. 5,000 kJ m-2yr-1

44. Good luck tomorrow! Be on time!!