Answer Part 2: sub part (b) AP FREE-RESPONSEPRACTICE1. Read the excerpt below and answer the questions that follow.Native species of North America are often defined asthose species that were present in North America beforeEuropeans arrived in the early 1600s. When Europeansarrived, they found extensive forests dominated by theAmerican chestnut tree. These chestnut trees were ex-tensively cultivated and planted by the North Americannatives for food and other wood products. In the early1900s, the chestnut blight (a fungus) virtually extermi-nated all of the American chestnut trees in NorthAmerica.(a) Classify the American chestnut tree as either a native or an introduced species. Explain your classification.(b) Classify the chestnut blight as either a native or an introduced species. Explain your classification.(c) The introduction of invasive species can be deliberate or accidental.(i) Identify TWO characteristics of an invasive species.(ii) Identify which of the species (American chestnut or chestnut blight) is considered invasive.(d) Many non-native game animals, for example, axis deer and blackbuck antelope, were deliberately introducedto the United States for the sport hunting industry.(i) Describe ONE ecological and ONE economic advantage of the introduction of game species.(ii) Describe ONE ecological and ONE economic disadvantage of the introduction of game species.2. Energy flow is a central theme throughout the study of environmental science. Consider energy flow when answer-ing the following questions:(a) The tundra/arctic biome is populated with lichens and grasses as dominant producers, small rodents calledlemmings, brown bears (grizzlies), caribou (deer family), and arctic wolves. Diagram a food web that correctlyshows the flow of energy through the species shown in the squares below.LichensArctic wolvesBrown bearsCaribouLemmingsGrasses(b) The tundra, like most biomes, has very few large predators that function at the highest levels of the trophicpyramid. Explain this phenomenon.(c) An ecologist is doing an in-depth study of a tundra ecosystem. He does a biomass sample of the producers inan area and measures 3.5 kilograms of producer biomass per square meter. Calculate the biomass of pro-ducers in terms of kilograms per hectare (kg/ha). A hectare contains 10,000 square meters.(d) Based on your calculation of kg/ha above:(i) Calculate the approximate biomass of both primary and secondary consumers that could be maintainedin one hectare of this ecosystem.(ii) Explain your calculation.(e) Many people suggest that it would be wiser for humans to eat lower on the trophic pyramid. Discuss thisstatement in terms of both energy availability and land use.APⓇ REVIEW QUESTIONS UNIT 2 233

Biomes: Biomes are significant because they are vast geographical units typified by a certain kind of flora and its accompanying wildlife. The wide range of environmental circumstances results in a wide range of plants, as well as the animal life it supports. Answer 2 b). Tundra is distinguished by its low temperatures and absence of trees. The most difficult obstacles for creatures in a tundra habitat are surviving the freezing temperatures and acquiring and retaining sufficient water.The Arctic and Antarctic tundras are situated at extreme latitudes, which correspond to a lack of direct sunlight and severely cold temperatures. The temperatures are so low that the earth is continuously frozen barely a foot below the surface all year.Because indirect sunlight is less effective for photosynthesis than direct sunlight, plants in this biome are unable to produce as much sugar as plants in other biomes. High winds also occur in the tundra biome, preventing plants (such as the moss in this image) from growing tall and from developing broad leaves to capture the sun's rays.Animals rely on the capacity to utilize the energy produced by plants through photosynthesis. Reduced photosynthesis means less energy available to animals in an environment. The primary consumers depend upon plants. On primary consumers secondary consumers are dependent and on secondary consumers tertiary consumers are dependent. If plants are rare due to extreme conditions and this will definitely affect the tertiary consumers also. Hence producers in the tundra have fewer predators at the highest level of the pyramid in the region. As a result, that environment will be able to support fewer animal species, and biodiversity will be limited.Conclusion: Since indirect sunlight is less effective for photosynthesis than direct sunlight, plants in this biome are unable to produce as much sugar as plants in other biomes.