Identify the choice that best completes the statement or answers the question

57 While reading a nature magazine, Sheila learned that spadefoot toads are common in areas with high daytime temperatures, limited rainfall, and cacti as the primary vegetation. Which biome would spadefoot toads MOST likely inhabit?

58 Which occurrence is a major source of the gases that can produce acid rain?

59 Which of the following is an abiotic factor in an ecosystem?

60 Which of the following practices is MOST likely to slow the buildup of CO2 in the atmosphere?

61 Predators often feed on weak or sick animals in an ecosystem. The role of the predator is described as its

62 Which of these can help farmers counteract the negative effects on their soil?

63 Organisms in an ecosystem are linked together by

64 Polar bears swim across large expanses of ocean while hunting for seals, their main source of food. The bears use sea ice as resting spots during their long swims. However, the sea ice is rapidly melting as a result of global warming. Which statement describes what most likely will happen if global warming continues at its present rate?

65 A forest fire destroys the majority of the trees in a state park. Which effect will this most likely have on secondary consumers in that ecosystem?

66 A new species of snake was introduced to a tropical region. Scientists then noticed a steady decline in the presence of field mice and an increase in the number of snakes. Which of these is the most likely explanation about why the population size of each animal changed?

67 Which of these best describes mutualism?

68 Which abiotic factor limits the altitude at which plants can grow?

69 Bacteria living in nodules on the roots of legumes have the ability to fix atmospheric nitrogen into a water-soluble form that plants can use. The bacteria absorb sugar from the plants’ roots. Which describes the relationship between the bacteria and the legume plants?

70 Which situation would result in the greatest increase in the human population?

71 A community is studied and several interactions are observed and recorded.

72 Silt and nutrients from eroding farmland flow into a lake. As a result, which will most likely increase first?

73 Why do ecosystems rarely contain more than a few trophic levels?

74 This diagram shows a food web of a meadow.

Due to insecticides, the cricket population is greatly reduced. Which population is most

affected by this event?

F	Mouse	H	Grass
G	Hawk	J	Frog

75 The crab Lybia tessellata carries a pair of sea anemones on its claws. The crab uses the sea anemone’s stinging tentacles as protection and the sea anemone obtains small food particles released by the crab as it feeds. Which type of symbiotic relationship does this best illustrate?

76 In an ecosystem, which is the most likely reason for an increase in the producer population if there is an increase in the carnivore population?

77 Which graph represents the maximum carrying capacity of a bacterial colony?

A		C
B		D

78 Which sequence shows increasing ecological levels of organization?

79 This diagram shows the flow of carbon in a terrestrial ecosystem.

Which will most likely happen if the decomposers are removed from the carbon cycle?

80 The diagram below represents an energy pyramid.

At each successive level from E to H, the amount of available energy

81 One possible reason for the rise in the average air temperature at Earth’s surface is that

82 Which concept is best represented in the diagram shown below?

83 A major reason that humans can have such a significant impact on the ecological community is that humans

84 Assume the trend in the graph above continues. Which of the following would result:

85 Cutting down a rain forest and planting agricultural crops, such as coffee plants, would result in

86 Two closely related species of birds live in the same tree. Species A feeds on ants and termites, while species B feeds on caterpillars. The two species coexist successfully because they