The substance removed from the atmosphere for plants to carry out photosynthesis is carbon dioxide (CO2).

Here's why:

* Photosynthesis: This process uses light energy to convert carbon dioxide and water into glucose (sugar) and oxygen.

* CO2 as a reactant: Carbon dioxide is a key reactant in photosynthesis. Plants absorb it through tiny pores on their leaves called stomata.

* Oxygen as a byproduct: During photosynthesis, plants release oxygen into the atmosphere as a byproduct.

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