Which of the following conditions is NOT necessary for photosynthesis to take place?

Analyze the question: You are asked to find the condition that is NOT needed for photosynthesis.

Explain the concept: Photosynthesis is the process by which green plants make food (glucose) from simple raw materials.

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

The requirements are:

• Chlorophyll: the green pigment that traps light energy
• Light: the energy source
• Carbon(IV) oxide (CO₂): the carbon source
• Water: the source of hydrogen

Step-by-step check of the options:

• A. Chlorophyll: needed to absorb light energy. Necessary.
• B. Light: needed to drive the reaction. Necessary.
• C. Carbon(II) oxide (CO): this is carbon monoxide, a poisonous gas. Plants do not use it in photosynthesis. NOT necessary.
• D. Carbon(IV) oxide (CO₂): the raw material for making glucose. Necessary.

Answer: The condition that is NOT necessary is Carbon(II) oxide, which is option C.

Exam tip: Watch the Roman numerals in chemical names. Carbon(II) oxide is CO, while carbon(IV) oxide is CO₂. JAMB often puts both in the same question to test whether you read carefully. For photosynthesis, always remember: CO₂, H₂O, light, chlorophyll.