Question

the earth review

1. which two processes cycle carbon directly

between the atmosphere and biosphere?
a. combustion and cellular respiration
b. photosynthesis and cellular respiration
c. chemosynthesis and decomposition
d. decomposition and combustion

Explanation:

To solve this, we analyze each option:

• Option a: Combustion (burning of fossil fuels/biomass) releases CO₂ to the atmosphere, but cellular respiration is part of the cycle. However, combustion is more of a human - induced process and not the direct main cycle between atmosphere and biosphere as photosynthesis - respiration.
• Option b: Photosynthesis (plants take in CO₂ from the atmosphere to make glucose) and cellular respiration (organisms release CO₂ back to the atmosphere by breaking down glucose) are the two key processes that directly cycle carbon between the atmosphere (CO₂) and biosphere (living organisms).
• Option c: Chemosynthesis is used by some organisms to make food using chemical energy (not directly related to carbon cycling between atmosphere and biosphere in the main way), and decomposition breaks down dead matter, which is part of the carbon cycle but not a direct cycle between atmosphere and biosphere like photosynthesis and respiration.
• Option d: Decomposition and combustion are part of the carbon cycle but not the direct processes that cycle carbon between atmosphere and biosphere.

Answer:

b. Photosynthesis and cellular respiration