Trophic Levels - AP Environmental Science

1. Identify a primary producer in an aquatic ecosystem.

   Phytoplankton. Microscopic plants that form the base of marine food webs.

2. What term describes the total energy captured by producers?

   Gross primary productivity. Total energy fixed by photosynthesis before respiration losses.

3. What is a food web?

   A complex network of interlinked food chains. Shows multiple feeding relationships and energy pathways.

4. What is the primary source of energy for most ecosystems?

   Sunlight. Powers photosynthesis in primary producers.

5. Identify the type of consumer that eats both plants and animals.

   Omnivores. They can function at multiple trophic levels simultaneously.

6. What trophic level do carnivores that eat herbivores occupy?

   Secondary consumers. They consume primary consumers (herbivores).

7. Which organisms are at the base of the food chain in the ocean?

   Phytoplankton. Primary producers that convert sunlight into chemical energy.

8. Identify the top predators in a food chain.

   Tertiary consumers. They eat secondary consumers and have few natural predators.

9. What is the definition of a trophic level?

   A rank in the food chain or food web of an ecosystem. Shows feeding positions and energy flow in ecosystems.

10. State one consequence of removing a top predator from an ecosystem.

    Disruption of trophic balance. Can lead to prey population explosions and ecosystem instability.

11. Identify a factor that affects the length of food chains.

    Energy availability. Limited energy restricts the number of sustainable trophic levels.

12. Identify the initial energy source for chemosynthetic ecosystems.

    Chemical energy from hydrothermal vents. Used by chemosynthetic bacteria instead of sunlight.

13. Which level of the food web do detritivores belong to?

    Decomposers. They consume dead organic matter and waste products.

14. What is the role of omnivores in a food chain?

    Consume both plants and animals. They occupy multiple trophic levels as both primary and secondary consumers.

15. What is the significance of keystone species in trophic levels?

    They play a critical role in maintaining ecosystem balance. Their removal can cause cascading effects throughout the ecosystem.

16. Which process converts solar energy into chemical energy?

    Photosynthesis. Used by plants to create glucose from carbon dioxide and water.

17. Which trophic level do herbivores belong to?

    Primary consumers. They feed directly on producers (plants).

18. Name an organism that functions as a decomposer.

    Fungi. Breaks down organic matter and recycles nutrients.

19. What percentage of energy is typically lost between trophic levels?

    90%. Due to metabolic processes and heat loss.

20. State the formula for calculating energy transfer efficiency.

    $\frac{\text{Energy at higher trophic level}}{\text{Energy at lower trophic level}} \times 100$. Measures the percentage of energy transferred between levels.

21. What is the primary purpose of a food chain?

    To illustrate energy flow through an ecosystem. Shows the linear transfer of energy between organisms.

22. Identify a key difference between food webs and food chains.

    Food webs show multiple interactions; chains are linear. Webs are more realistic representations of ecosystem complexity.

23. What is the role of decomposers in an ecosystem?

    Break down dead material and recycle nutrients. Essential for nutrient cycling in ecosystems.

24. What is a pyramid of biomass?

    A graphical representation of biomass at each trophic level. Typically pyramid-shaped due to energy loss at each level.

25. What is the term for energy lost as heat at each trophic level?

    Entropy. Energy dissipated during metabolic processes at each level.

26. Define biomass in the context of trophic levels.

    Total mass of organisms at a trophic level. Decreases at higher trophic levels due to energy loss.

27. Which organisms are considered heterotrophs?

    Consumers (herbivores, carnivores, omnivores). They cannot produce their own food and must consume other organisms.

28. What term describes organisms that produce their own food?

    Autotrophs. They make their own food through photosynthesis or chemosynthesis.

29. What is the typical energy transfer efficiency between trophic levels?

    Approximately 10%. Known as the 10% rule in ecology.

30. What is the name for organisms that feed exclusively on plants?

    Herbivores. Primary consumers that only eat plant material.

31. What is the significance of the 10% rule in energy transfer?

    Only 10% of energy is passed to the next trophic level. Explains why food chains are typically short.

32. Identify the primary producers in a terrestrial ecosystem.

    Plants. They convert sunlight into chemical energy through photosynthesis.

33. Which trophic level has the most available energy?

    Primary producers. They capture energy directly from the sun through photosynthesis.

34. Which trophic level contains organisms like mushrooms?

    Decomposers. Fungi that break down dead organic material.

35. What is the role of an apex predator?

    Top of the food chain; no natural predators. Controls prey populations and maintains ecosystem balance.

36. Identify the process through which energy is transferred in food webs.

    Consumption. One organism eating another transfers energy up trophic levels.

37. What is net primary productivity?

    Energy available to consumers after plant respiration. Energy remaining after producers use some for cellular respiration.

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