Question

1. carbon cycle

photosynthesis _________________ carbon dioxide from the atmosphere.
cellular respiration _________________ carbon dioxide into the atmosphere.
combustion _________________ carbon dioxide into the atmosphere.

Explanation:

In the carbon cycle, photosynthesis is the process by which plants (and some other organisms) take in (absorb) carbon dioxide from the atmosphere to use in producing glucose and oxygen. Cellular respiration is the process by which organisms break down glucose (or other organic compounds) and release carbon dioxide back into the atmosphere. Combustion, like burning fossil fuels or biomass, also releases carbon dioxide into the atmosphere. So the correct verbs to fill in are "absorbs" (or "takes in") for photosynthesis, "releases" for cellular respiration, and "releases" for combustion.

Answer:

• Photosynthesis \underline{absorbs (takes in)} carbon dioxide from the atmosphere.
• Cellular respiration \underline{releases} carbon dioxide into the atmosphere.
• Combustion \underline{releases} carbon dioxide into the atmosphere.