Nutrient Cycles - Carbon Cycle

The question asks which process removes CO₂ from the atmosphere and converts it to organic compounds.

Photosynthesis is the process by which plants use light energy, water, and CO₂ to produce glucose and oxygen: $6C{O}_2+6H_{2}O\to C_6{H}_{12}{O}_6+6O_2$.

Photosynthesis converts inorganic carbon (CO₂) from the atmosphere into organic carbon (glucose) stored in plant tissue — exactly what the question describes.

Photosynthesis is the correct answer.

Respiration breaks down organic compounds and releases CO₂ into the atmosphere — the opposite of what the question describes.

Decomposition breaks down dead organic matter and also releases CO₂ through decomposers' respiration — it does not remove CO₂ from the atmosphere.

Combustion burns fuels and releases CO₂ — again, the opposite direction of carbon movement described.

Only Photosynthesis removes CO₂ from the atmosphere and stores it as organic carbon — making it the correct answer.

Aerobic respiration requires glucose ($C_6{H}_{12}{O}_6$) and oxygen ($O_2$) as reactants (inputs).

The products are carbon dioxide ($C{O}_2$), water ($H_{2}O$), and energy.

The equation $C_6{H}_{12}{O}_6+6O_2\to 6C{O}_2+6H_{2}O+\text{energy}$ has 6 carbon, 12 hydrogen, and 18 oxygen atoms on each side — it is balanced.

The first option correctly shows glucose and oxygen as reactants producing CO₂, water, and energy.

The second equation ($6C{O}_2+6H_{2}O\to C_6{H}_{12}{O}_6+6O_2$) is the equation for photosynthesis, not respiration.

The third option produces $H_2$ gas, which is not a product of aerobic respiration — water ($H_{2}O$) should be produced instead.

The fourth option has $O_2$ and $H_{2}O$ as reactants producing glucose — this is not a recognised biochemical process in this context.

Only the first option correctly represents aerobic respiration with glucose and oxygen as inputs and CO₂, water, and energy as outputs.