Which of the following processes removes carbon (IV) oxide from the atmosphere?

Step 1: Analyze the question The question asks which process removes CO₂ from the atmosphere. This means we need a process that takes in CO₂, not one that releases it.

Step 2: Explain the concept Carbon (IV) oxide moves through the carbon cycle:

• Added to the atmosphere by combustion (burning fuels, wood), respiration (in plants, animals and microbes), decay, and volcanic activity.
• Removed from the atmosphere mainly by photosynthesis, where green plants absorb CO₂ and use it to make food.

Photosynthesis equation:

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (in the presence of light and chlorophyll)

Step 3: Check each option

• A. Combustion: Burning releases CO₂. ❌
• B. Excretion: Removes metabolic wastes from the body (CO₂ is released from the body in the process, which adds to the atmosphere). ❌
• C. Photosynthesis: Plants take in CO₂ from the air to make glucose. ✅
• D. Respiration: Breaks down food and releases CO₂. ❌
• E. Transpiration: Loss of water vapour from plants. It has nothing to do with CO₂ removal. ❌

Step 4: Answer The correct option is C. Photosynthesis.

Tip: Remember the opposites: Photosynthesis takes in CO₂ and gives out O₂; respiration and combustion take in O₂ and give out CO₂. If a question asks about "removing" CO₂, think "green plants and sunlight."