Energy Flow and the 10% Rule - AP Environmental Science

1. What type of pyramid shows the number of organisms in each trophic level?

   Pyramid of numbers. Shows organism abundance at each level.

2. What occurs to energy not transferred to the next trophic level?

   It is lost as heat or used in metabolism. Energy dissipates through cellular respiration.

3. Determine the energy at the third trophic level if 1000 J is at the first.

   10 J. Two 10% transfers: $1000 \times 0.1 \times 0.1 = 10$ J.

4. What is the energy efficiency of a trophic level if 25 J is transferred from 250 J?

   10%. $\frac{25}{250} \times 100 = 10$% efficiency.

5. Calculate the energy loss if 5000 J is reduced to 500 J in the next level.

   4500 J. Energy lost: $5000 - 500 = 4500$ J.

6. Find the energy transferred to the next level if 5000 J is consumed.

   500 J. Apply the 10% rule: $5000 \times 0.1 = 500$ J.

7. Which type of organism occupies multiple trophic levels?

   Omnivores. They consume both plants and animals.

8. Which organisms decompose organic material and return nutrients to soil?

   Decomposers. Bacteria and fungi recycle nutrients.

9. Identify the type of organism at the base of an energy pyramid.

   Producers. Autotrophs capture solar energy at the base.

10. State the main reason for energy loss between trophic levels.

    Heat loss due to metabolic processes. Cellular respiration releases energy as heat.

11. What percentage of energy do secondary consumers receive from producers?

    1%. Two 10% transfers from original producers.

12. Identify the primary source of energy in most ecosystems.

    The Sun. Solar radiation drives photosynthesis in producers.

13. State the energy transfer efficiency if 10 J is gained from 100 J.

    10%. $\frac{10}{100} \times 100 = 10$% efficiency.

14. Identify the trophic level of apex predators.

    Top trophic level. Highest consumers in the food chain.

15. What is the main cause of energy loss in food chains?

    Metabolic heat. Thermal energy lost during cellular processes.

16. What percentage of energy is typically lost as heat?

    90%. Most energy converts to heat during metabolism.

17. What is the effect of energy loss on ecosystem structure?

    Fewer organisms at higher trophic levels. Energy constraints limit higher level populations.

18. Choose the correct term: Energy pyramids show energy flow in a(n) ______.

    ecosystem. Energy flows through interconnected communities.

19. Calculate energy transfer if 2000 J is available and 10% is passed on.

    200 J. 10% of 2000 J equals 200 J transferred.

20. State the formula for energy transfer efficiency between trophic levels.

    Efficiency = $\frac{\text{Energy to next level}}{\text{Energy from previous level}} \times 100$. Calculates percentage of energy passing between levels.

21. Which trophic level do herbivores belong to?

    Second trophic level. Primary consumers feed directly on producers.

22. Identify the term for energy not used in growth or reproduction.

    Respired energy. Energy used for maintenance, not biomass.

23. Identify the form of energy transfer that is not 100% efficient.

    Trophic transfer. Energy decreases between feeding levels.

24. Identify the process by which energy is lost as heat in organisms.

    Respiration. Cellular process that releases thermal energy.

25. What trophic level are primary producers located at?

    First trophic level. Producers form the base of energy pyramids.

26. What is the 10% rule in energy transfer?

    Only 10% of energy is transferred to the next trophic level. 90% is lost as heat during metabolic processes.

27. Calculate energy efficiency if 50 J is transferred from 500 J.

    10%. $\frac{50}{500} \times 100 = 10$% efficiency.

28. What is the typical shape of an energy pyramid?

    Pyramid shape. Energy decreases at each ascending level.

29. Identify the term for organisms that consume producers.

    Primary consumers. Herbivores that eat producers directly.

30. Identify the unit commonly used to measure energy in ecosystems.

    Joules (J). Standard unit for measuring energy transfer.

31. What term describes the 90% of energy not transferred to the next level?

    Energy loss. Energy dissipated and unavailable for transfer.

32. Which law of thermodynamics explains energy loss as heat?

    Second law of thermodynamics. States energy becomes less useful over time.

33. Calculate the energy available at the fourth trophic level if 1000 J starts at the first.

    1 J. Three 10% transfers: $1000 \times 0.1^3 = 1$ J.

34. What is the role of decomposers in energy flow?

    Decomposers break down dead matter and recycle nutrients. They return energy to the ecosystem base.

35. Find total energy loss if 1000 J is at first level, reaching 10 J at third.

    990 J. Total lost: $1000 - 10 = 990$ J.

36. What term describes the energy trapped by producers from sunlight?

    Gross primary productivity. Total energy captured through photosynthesis.

37. Find the percentage of energy transferred if 300 J is passed from 3000 J.

    10%. $\frac{300}{3000} \times 100 = 10$% efficiency.

38. Identify the process by which producers capture solar energy.

    Photosynthesis. Converts light energy into chemical energy.

39. What is the relationship between biomass and energy in ecosystems?

    Biomass decreases as energy decreases up the trophic levels. Less biomass supports higher trophic levels.

40. What is the energy available to herbivores from plants called?

    Net primary productivity. Energy remaining after plant respiration.

Study these flashcards