CAST-Segment 5-ESS3-6

Which of the following best describes how an increase in atmospheric carbon dioxide (CO₂) can impact the ocean?

• Increased CO₂leads to increased ocean temperatures, causing coral bleaching

• Increased CO₂ leads to ocean acidification, harming marine organisms with calcium carbonate shells.

• Increased CO₂ directly poisons marine life, leading to mass die-offs.

• Increased CO₂ has no significant impact on the ocean.

Answer explanation

Answer: b) Increased CO2 leads to ocean acidification, harming marine organisms with calcium carbonate shells.

Explanation:

• When CO2 dissolves in seawater, it forms carbonic acid, which increases the acidity of the ocean.

• This acidification can dissolve the calcium carbonate shells and skeletons of many marine organisms, such as corals, shellfish, and some plankton.

How can deforestation contribute to climate change?

• Trees absorb CO2 from the atmosphere during photosynthesis, so deforestation reduces CO2 uptake.

• Deforestation increases the amount of water vapor in the atmosphere, a greenhouse gas.

• Cutting down trees releases stored carbon back into the atmosphere.

• All of the above.

Answer explanation

Answer: d) All of the above.

Explanation:

• Deforestation has multiple impacts on climate change:

  • Trees absorb CO₂ from the atmosphere during photosynthesis, so removing them reduces this carbon uptake.

  • Deforestation releases stored carbon back into the atmosphere when trees are burned or decompose.

  • Reduced forest cover can also alter regional climate patterns, including changes in rainfall and temperature.

How can the melting of glaciers and ice sheets impact sea level and coastal ecosystems?

• Melting ice adds freshwater to the oceans, causing sea levels to rise and inundating coastal areas.

• Melting ice has no significant impact on sea level.

• Melting ice actually lowers sea levels due to increased evaporation.

• Melting ice primarily affects local ecosystems and has minimal impact on global sea levels.

Answer explanation

Answer: a) Melting ice adds freshwater to the oceans, causing sea levels to rise and inundating coastal areas.

Explanation:

• As glaciers and ice sheets melt, the added water flows into the oceans, causing sea levels to rise.

• This can lead to coastal erosion, flooding, and the displacement of coastal communities and ecosystems.

Which of the following is an example of how human activities can disrupt the nitrogen cycle?

• a) Excessive use of fertilizers can lead to nutrient runoff into waterways.

• b) Burning fossil fuels releases nitrogen oxides into the atmosphere.

• c) Both a and b

• d) Neither a nor b

Answer explanation

Answer: c) Both a and b

Explanation:

• Human activities significantly impact the nitrogen cycle:

  • Excessive use of nitrogen fertilizers in agriculture can lead to nutrient runoff, polluting waterways and causing algal blooms.

  • Burning fossil fuels releases nitrogen oxides into the atmosphere, contributing to air pollution and acid rain.

How can computational models help scientists understand the complex interactions within Earth's systems?

• Models can simulate how different factors interact and influence each other within the Earth system.

• Models provide simple, linear representations of Earth systems.

• Models are not useful for understanding complex systems like Earth.

• Models can only predict future events, not understand past interactions.

Answer explanation

Answer: a) Models can simulate how different factors interact and influence each other within the Earth system.