Question

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 (air)
- Biosphere (all living things)
- Hydrosphere (oceans, lakes, water)
- Geosphere/Lithosphere (rocks, soils, fossil fuels)

How living things are involved (visible and invisible)
- Plants, algae: photosynthesis — take CO2 from the atmosphere/water and build organic carbon (visible).
- Animals: eat plants/other animals, transfer carbon through food webs (visible).
- Microbes & fungi (often invisible): decompose dead matter, returning carbon as CO2 or CH4.
- Cellular processes (invisible): enzymes in cells drive photosynthesis and respiration.
- Respiration (plants, animals, microbes): break down organic carbon and release CO2.
- Oceans & phytoplankton (some visible, mostly microscopic): absorb CO2, store it as organic/inorganic carbon.
- Long-term storage (mostly invisible): burial, rock formation, and fossil fuels lock carbon away for geologic time.
- Humans: harvest biomass, burn fossil fuels, change land use — move stored carbon back to the atmosphere.

Short answers to the questions
- Relationship between cellular respiration and photosynthesis:
Photosynthesis removes CO2 and converts it to organic carbon; cellular respiration breaks down organic carbon and releases CO2. They are complementary parts of the carbon cycle.
- Impacts of human-derived carbon sources:
Burning fossil fuels, deforestation, cement production, and some agriculture add extra CO2 and CH4, raising atmospheric greenhouse gases, causing warming, ocean acidification, and disrupting natural carbon sinks.
- Why use models instead of the real things:
Models simplify complex systems, let you test ideas and make predictions, allow study at different scales and times safely and cheaply, and help visualize processes you can’t observe directly.