Question

How do plants contribute to the carbon cycle? a. When plants respire, they release \(\mathrm{CO}_{2}\) into the atmosphere b. When plants photosynthesize, they consume \(\mathrm{CO}_{2}\) from the atmosphere. c. When plants photosynthesize, they provide oxygen to heterotrophs. d. When plants emigrate, they transport carbon molecules between ecosystems. e. Both a and b are correct.

Short answer

Plants contribute to the carbon cycle through processes such as respiration and photosynthesis. During respiration, plants release \(\mathrm{CO}_{2}\) into the atmosphere, and during photosynthesis, they consume \(\mathrm{CO}_{2}\) from the atmosphere. Therefore, the answer is e. Both a and b are correct.

Step-by-step solution

Option a - Analyzing when plants respire

When plants respire, they break down stored glucose (sugars) and release the energy required for their metabolic processes. During respiration, plants consume oxygen and produce \(\mathrm{CO}_{2}\) as a byproduct, which gets released into the atmosphere. Thus, this part is correct.

Option b - Analyzing when plants photosynthesize

During photosynthesis, plants absorb \(\mathrm{CO}_{2}\) from the atmosphere and use sunlight to convert it along with water into glucose (sugars) and oxygen. As a result, plants serve as a sink for carbon dioxide, effectively removing it from the atmosphere. This part is also correct.

Option c - Analyzing plants providing oxygen to heterotrophs

Although it's true that during photosynthesis, plants produce and release oxygen, which is essential for the survival of heterotrophs, this option does not directly explain how plants contribute to the carbon cycle. Therefore, this part is not considered in our answer.

Option d - Analyzing when plants emigrate

Plants do not emigrate in the typical sense that animals do. They can disperse seeds and expand their range, but this does not involve transporting carbon molecules between ecosystems as a direct part of the carbon cycle. Hence, this part is incorrect.

Conclusion

Based on our analysis, both option a (when plants respire, they release 𝖢𝖮₂ into the atmosphere) and option b (when plants photosynthesize, they consume 𝖢𝖮₂ from the atmosphere) are correct. Therefore, the final answer is e. Both a and b are correct.

Key concepts

Plant Respiration

Plant respiration is a vital process in the carbon cycle. During respiration, plants take in oxygen and use it to break down stored food, like glucose, to release the energy they need for growth and other functions. This process results in the production of carbon dioxide \((CO_2)\) and water as byproducts.
Although plants produce their food through photosynthesis and generate oxygen, they, like animals, consume oxygen for respiration. The carbon dioxide released during respiration becomes part of the atmospheric reservoir of \(CO_2\).

• This balance of releasing and absorbing carbon dioxide is a key aspect of the carbon cycle.
• Respiration ensures that the carbon stored in plant tissues as glucose, returns to the atmosphere, where it can again be used in photosynthesis.

This cyclical exchange highlights the importance of plant respiration in regulating and maintaining the flow of carbon in ecosystems.

Photosynthesis

Photosynthesis is the process by which plants convert light energy into chemical energy in the form of glucose. By utilizing sunlight, water, and carbon dioxide \((CO_2)\) from the atmosphere, plants synthesize glucose, a form of sugar, and release oxygen as a byproduct.
This process not only provides essential nutrients for the plant's own growth but also supports life on Earth by acting as a carbon sink.

• The absorption of \(CO_2\) by plants helps manage and reduce atmospheric carbon levels, which is crucial in ongoing climate change mitigation efforts.
• Photosynthesis sustains the oxygen supply that is indispensable for the survival of animals and other non-photosynthetic organisms, known as heterotrophs.

Overall, photosynthesis plays a dual role in capturing atmospheric carbon and producing oxygen, reinforcing the interconnectedness of all living things within ecosystems.

Carbon Dioxide Exchange

Carbon dioxide exchange refers to the process by which \(CO_2\) moves between the atmosphere and living organisms. Plants play a central role in this exchange by absorbing \(CO_2\) during photosynthesis and releasing it during respiration.

• This dual action creates a dynamic equilibrium within the carbon cycle, maintaining stable levels of \(CO_2\) in the atmosphere.
• The ocean and soil also contribute to this exchange by absorbing and storing \(CO_2\), further regulating global atmospheric levels.

Understanding this exchange is crucial for studying how changes in plant populations, deforestation, or increased carbon emissions can impact the broader carbon cycle and ultimately affect climate patterns.
This continuous cycle of \(CO_2\) transfer between different components of Earth's system emphasizes the need for sustainable practices that preserve natural carbon sinks.

Ecosystems

Ecosystems are complex networks of living organisms interacting with their physical environment. They play a pivotal role in the carbon cycle because they regulate the flow and storage of carbon through various processes.
Plants, as primary producers, are integral to ecosystems, converting atmospheric \(CO_2\) into organic material that becomes the foundation of food webs.

• Decomposers, such as fungi and bacteria, contribute by breaking down dead organic matter, returning \(CO_2\) to the atmosphere.
• Herbivores and carnivores further drive the cycle by consuming plants and animals, respectively, and respiring \(CO_2\).

The balance within ecosystems is crucial since any disruption can lead to an accumulation or deficit of carbon, influencing climate and the availability of resources. Healthy, biodiverse ecosystems offer resilience and sustainability, supporting both the environment and human society.