Unit 2: Ecological Concepts and Energy Flow - Practice Quiz

1 What is an ecosystem?

2 Which of the following is a biotic component of an ecosystem?

3 Which of the following is an abiotic component?

4 At which trophic level are green plants usually found?

5 What is the usual role of a herbivore in a food chain?

6 Which organism is most likely to be a decomposer?

7 What does a pyramid of numbers show?

8 Which ecological pyramid is always upright?

9 In an ecological pyramid, producers are placed at the:

10 What is an ecological niche?

11 Which factor can be part of an organism's ecological niche?

12 What is the main source of energy for most ecosystems?

13 How does energy generally move through an ecosystem?

14 What happens to much of the energy as it passes between trophic levels?

15 Which sequence is a correct food chain?

16 What does an arrow in a food chain usually show?

17 What is a food web?

18 Why are food webs generally more realistic than simple food chains?

19 Which cycle includes the processes of evaporation, condensation, and precipitation?

20 Which gas is exchanged between organisms and the atmosphere during the carbon cycle?

21 A pond contains algae, fish, bacteria, dissolved minerals, sunlight, and water. Which pair represents only biotic components?

22 If decomposers were removed from a forest ecosystem, which change would most likely occur first?

23 In the food chain grass → grasshopper → frog → snake, which organism occupies the third trophic level?

24 A bird feeds on seeds and insects. How should the bird's trophic position be described?

25 Which ecological pyramid is most likely to be inverted in a marine ecosystem?

26 Why can a pyramid of energy never be inverted?

27 Two bird species eat the same insects in the same tree canopy. Which change would most directly reduce competition between them?

28 A species survives in a laboratory under a wide range of conditions but occupies a narrower range in nature. The narrower range is its:

29 Which statement correctly compares energy flow with nutrient cycling in an ecosystem?

30 If producers capture 12,000 kJ of energy and approximately 10% is transferred at each trophic level, how much reaches the tertiary consumers after three transfers?

31 In the chain phytoplankton → zooplankton → small fish → large fish, which organism receives energy directly from the producer?

32 Pesticides that are not easily broken down enter a food chain. Which organism is likely to have the highest concentration?

33 If all grass in a grassland food chain suddenly disappeared, which population would be affected most directly?

34 Why is a food web generally more stable than a single food chain?

35 In a food web, a predator that eats several herbivore species is removed. What is the most likely immediate effect?

36 An invasive species consumes the same fruits as a native bird and has no natural predators in the new habitat. Which interaction is most likely?

37 Which process converts atmospheric nitrogen into a form that plants can use more directly?

38 Excess fertilizer enters a lake and causes algal blooms. Why may fish later die in large numbers?

39 Deforestation can increase atmospheric carbon dioxide mainly because it:

40 Which sequence correctly represents a major part of the water cycle?

41 A coastal wetland is connected to the sea by a narrow channel. If tidal exchange is suddenly blocked while sunlight, rainfall, and local species remain unchanged, which component-level change is most likely to occur first?

42 In an ecosystem, gross primary productivity is units, plant respiration is units, and herbivore consumption is units. Which statement is correct about the plant community?

43 A fish obtains of its diet from herbivorous zooplankton and from carnivorous zooplankton that feed only on herbivorous zooplankton. What is the fish's approximate trophic level?

44 A predator consumes equal biomass of primary consumers and secondary consumers. Assuming those prey have trophic levels and , respectively, what is the predator's trophic level?

45 In a lake, phytoplankton have a standing biomass of kg, while zooplankton have kg because phytoplankton reproduce rapidly. Which interpretation is most defensible?

46 An ecosystem has producer energy of kJ, primary-consumer energy of kJ, secondary-consumer energy of kJ, and tertiary-consumer energy of kJ. Which transfer is least efficient?

47 Two bird species use the same nesting sites, but one feeds mainly at dawn and the other mainly at dusk. Which conclusion best follows?

48 A species occupies a narrow range of salinity in the presence of a competitor but a much broader range when the competitor is experimentally removed. What does this demonstrate?

49 A keystone predator is removed from a rocky shore. One mussel species expands and excludes several algae species from exposed surfaces. Which ecological mechanism best explains the result?

50 Which statement correctly distinguishes energy movement from nutrient movement in an ecosystem?

51 A grassland receives kJ of solar energy. Producers capture , and each of three consumer transfers is efficient. Approximately how much energy reaches the tertiary consumers?

52 A nutrient is abundant in soil but unavailable to plants because it is chemically bound in an insoluble mineral. Which process would most directly increase its biological availability?

53 In the chain phytoplankton zooplankton small fish tuna, a persistent pollutant biomagnifies at each trophic transfer. Which organism should have the highest concentration?

54 A detrital food chain begins with fallen leaves, fungi, and earthworms and ends with a bird of prey. If fungal decomposers decline sharply, which immediate change is most likely?

55 In a food web, an apex predator declines. Herbivore abundance rises, vegetation falls, and stream-bank erosion increases. This sequence is best described as:

56 A food web contains two alternative prey species for a predator. A drought eliminates one prey species, but predator numbers remain stable because the predator switches to the other prey. This property is called:

57 A pesticide eliminates a predatory insect that normally suppresses herbivorous insects. Which short-term response is most plausible if plants are initially abundant?

58 Excess fertilizer enters a lake, stimulating algal growth. After the algae die, decomposition causes widespread fish mortality. Which sequence best explains the event?

59 Which human activity most directly transfers geologically stored carbon into the active atmospheric carbon cycle?

60 In a waterlogged soil, oxygen becomes scarce and nitrate is converted into gaseous nitrogen compounds that leave the soil. Which process is occurring?