Question

An illustration shows a model of the carbon cycle.
Source: danylyukk1/Shutterstock

An illustration shows the Carbon Cycle. Carbon in the form of carbon dioxide is released by animals during respiration. Carbon is also released by factories and vehicles in the form of smoke. Plants use this carbon during the process of photosynthesis. The plants and animals die and decompose in the form of organic carbon. The fossil fuels found deep in the ground are mineral carbon that is used for various purposes.
The model above shows how carbon is cycled through an ecosystem. In your Science Notebook, identify the four spheres through which carbon cycles, and then make a listing of how living things are related to the cycling of carbon. Be sure to consider both the things you can see and the things you cannot. Use your list to answer the following questions:

What is the relationship between cellular respiration and photosynthesis in terms of carbon cycling?
What are the impacts of human-derived carbon sources on the cycling of carbon?
Why would a scientist (or student) use models of the carbon cycle (or other phenomena) instead of the real things?
make it short

Answer 1

Four spheres:
- Atmosphere, Biosphere, Hydrosphere, Geosphere (lithosphere).

How living things are related (visible and invisible):
- Plants use CO2 for photosynthesis, storing carbon as sugars and biomass.
- Animals (and microbes) release CO2 through cellular respiration.
- Decomposers break dead organisms into organic matter and CO2.
- Some organisms become buried and—over long time—form fossil fuels (geosphere).
- Microbes also transform carbon chemically (e.g., methane production or oxidation).
- Living activity moves carbon between spheres (air ↔ living tissue ↔ soil/rocks ↔ water).

Short answers:
1) Relationship of respiration and photosynthesis:
- Photosynthesis removes CO2 from the atmosphere and builds organic carbon; respiration breaks organic carbon and returns CO2. They are complementary processes that loop carbon between organisms and the atmosphere.

2) Impacts of human-derived carbon sources:
- Burning fossil fuels and deforestation add extra CO2 to the atmosphere, driving climate change, warming, and ocean acidification; they unbalance the natural carbon cycle.

3) Why use models instead of real things:
- Models simplify complex systems, help visualize and predict changes, let you test scenarios safely and cheaply, and aid teaching and communication.