Question

Which of the following contribute(s) to the carbon cycle? a. respiration b. photosynthesis c. fossil fuel combustion d. decomposition of dead organisms e. All of these are correct.

Short answer

The correct answer is e: All of these are correct. Each option (respiration, photosynthesis, fossil fuel combustion, and decomposition of dead organisms) contributes to the carbon cycle in a different way, but all are involved in the process of moving carbon through the Earth's systems.

Step-by-step solution

Option a: Respiration

Respiration is the process where organisms take in oxygen and release carbon dioxide, which returns carbon to the atmosphere. Therefore, respiration contributes to the carbon cycle.

Option b: Photosynthesis

Photosynthesis is the process by which plants, algae, and some bacteria use sunlight energy to convert carbon dioxide from the atmosphere into organic compounds (carbon-based molecules), thus consuming carbon and integrating it into their biomass. Therefore, photosynthesis contributes to the carbon cycle.

Option c: Fossil fuel combustion

Fossil fuel combustion is the process of burning fossil fuels, such as coal, oil, and natural gas, to release energy. During this process, carbon dioxide is released back into the atmosphere, contributing to the carbon cycle.

Option d: Decomposition of dead organisms

Decomposition is the process where dead organisms are broken down into their respective components by decomposers such as bacteria and fungi. This process releases the carbon stored in these organisms back into the atmosphere or the soil in the form of carbon dioxide or organic compounds, thus contributing to the carbon cycle.

Conclusion

Since all the options (a, b, c, d) contribute to the carbon cycle, the correct answer is option e: All of these are correct.

Key concepts

Respiration

Respiration is a vital process that affects the carbon cycle. It is the method by which animals and plants convert sugars and oxygen into energy. In doing so, they release carbon dioxide back into the atmosphere. This carbon dioxide then becomes available for plants to use in photosynthesis.

• Occurs in both plants and animals.
• Involves exchange of carbon in the form of carbon dioxide.
• Essential for maintaining atmospheric CO2 levels.

Even though it might seem like respiration is only about taking in oxygen and giving out carbon dioxide, this process plays a significant role in keeping the carbon flowing in the ecosystem.

Photosynthesis

Photosynthesis is the incredible process by which plants, algae, and some bacteria capture sunlight and use it to transform carbon dioxide and water into food. This food takes the form of carbohydrates, which provide the energy and building material for plants, and oxygen, which is released into the air for us to breathe.

• Converts sunlight into chemical energy.
• Reduces atmospheric carbon dioxide levels.
• Framed as the opposite of respiration, creating a balance.

Photosynthesis is a crucial component of the carbon cycle as it is the primary method for the conversion of carbon dioxide into organic matter. Without it, there would be no oxygen for animals and humans, and carbon dioxide levels would rise uncontrollably.

Fossil Fuel Combustion

Fossil fuel combustion is one of the major contributors to the carbon cycle, primarily through human activity. When fossil fuels like coal, oil, and natural gas are burned, they release energy for electricity, transportation, and other needs. This burning process, however, also emits large amounts of carbon dioxide into the atmosphere.

• Main source: human industrial activity.
• Causes significant increase in atmospheric CO2.
• Linked to global climate change.

While it provides essential energy, fossil fuel combustion disrupts the natural carbon balance, contributing heavily to global warming and climate change. Reducing reliance on fossil fuels is a key step toward reducing carbon emissions.

Decomposition

Decomposition is the process by which organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide and water. This occurs through the actions of decomposers, mainly fungi and bacteria.

• Breaks down dead matter, returning nutrients to soil and atmosphere.
• Releases stored carbon back into the environment.
• Crucial for nutrient cycling in ecosystems.

As organisms die, decomposers play a vital role in recycling nutrients and carbon within ecosystems. This process helps maintain the carbon balance and allows for the continual cycling of carbon through the environment.