Which of the following does NOT occur during photosynthesis?

Analyze the question We need the one statement that does NOT happen during photosynthesis. Four of the options are true of the process, and one is false.

Concept Photosynthesis is summarized as:

6CO₂ + 6H₂O → (light energy, chlorophyll) → C₆H₁₂O₆ + 6O₂

It has two stages:

• Light stage (in the grana): Chlorophyll absorbs sunlight. Water is split (photolysis), releasing oxygen, hydrogen, and electrons.
• Dark stage (in the stroma): Carbon dioxide is taken in (fixed) and combined with hydrogen to form glucose.

Checking each option

• A. Carbon dioxide is evolved: This is false. CO₂ is absorbed (used up) in photosynthesis. It is given off in respiration.
• B. Energy from the sun is utilized: True. Light energy drives the process.
• C. Glucose is synthesized: True. Glucose is the main product.
• D. Oxygen is given off: True. It is a by-product of water splitting.
• E. Split of water: True. Photolysis of water occurs in the light stage.

Answer Option A is the statement that does not occur. Carbon dioxide is consumed, not evolved.

Exam tip Remember that photosynthesis and respiration are opposites with regard to gases:

• Photosynthesis: takes in CO₂, gives out O₂.
• Respiration: takes in O₂, gives out CO₂.

If an option says "CO₂ is evolved or given off," it describes respiration, not photosynthesis.