Free Response Questions (College Board AP® Environmental Science): Exam Questions

Biofuels, derived from plant material, are being promoted as an alternative to fossil fuels. While biofuels reduce CO₂ emissions compared to gasoline, they also have environmental drawbacks.

Identify one biomass-based fuel that can be used as an alternative to gasoline.

Explain why biofuels are considered carbon neutral in theory but may not be in practice.

Describe one disadvantage of large-scale corn-based ethanol production.

Explain how biofuel production could contribute to deforestation.

Explain one advantage of algae-based biofuels over corn-based biofuels.

Describe how government policies, such as subsidies, could influence biofuel adoption.

Identify one major limitation of replacing all fossil fuels with biofuels.

Describe one impact of increased biofuel demand on global food prices.

Explain how biofuel use could still contribute to climate change despite lower CO₂ emissions.

Propose a sustainable method to produce biofuels while minimizing environmental damage.

Humans use energy from a variety of sources, both renewable and non-renewable, resulting in positive and negative consequences.

Based on the data below, identify the form of renewable energy that has seen the greatest increase in generation since 2000.

US electricity generation from renewable sources (billion kWh)

Describe one environmental drawback associated with this form of energy.

Energy from biomass involves converting agricultural feedstocks into ethanol, which is often added to gasoline.

Describe what makes biofuel from corn or sugarcane a renewable resource.

Support or refute the claim that energy obtained from ethanol produced from agricultural feedstocks does not add additional carbon dioxide to the atmosphere.

Describe an unintended consequence of using agricultural feedstocks for biofuel production.

Describe a strategy to reduce the impact of the consequence you described in (e)

Currently, only the kernel of the corn plant, which is high in sugar, can efficiently be used for ethanol production. Using waste parts of the plant, which are made of cellulose, requires enzymes to break the complex carbohydrates into simple sugars. All energy use has advantages and disadvantages. 

Hydroelectric power is one of the oldest forms of renewable energy. The diagram below depicts a modern hydroelectric plant.

Identify the source of potential energy in the diagram.

Describe how hydroelectric dams can have a negative impact on aquatic ecosystems.

Propose a solution, other than switching to a different energy source, to mitigate the impacts of hydroelectric dams on aquatic ecosystems.

Justify the solution you proposed by describing an economic advantage.