Science — AI-generated practice question

Photosynthesis is the process by which green plants prepare food using simple inorganic substances in the presence of sunlight and chlorophyll.

Raw Materials: Carbon dioxide (CO₂) and water (H₂O).

Conditions Required: Sunlight and chlorophyll.

Products Formed: Carbohydrates (glucose/starch) and oxygen.

The overall process involves three main events:

1. Absorption of light energy by chlorophyll.
2. Conversion of light energy to chemical energy and splitting of water into hydrogen and oxygen.
3. Reduction of carbon dioxide to carbohydrates.

Role of Chlorophyll: Chlorophyll, present in chloroplasts, absorbs light energy and converts it into chemical energy, which drives the synthesis of carbohydrates.

Role of Stomata: Stomata are tiny pores on leaf surfaces through which CO₂ enters the leaf. Their opening and closing is regulated by guard cells — guard cells swell when water flows in (pore opens) and shrink when water flows out (pore closes). This controls both CO₂ intake and water loss.

Source: Chapter 5, Section 5.2.1 — Autotrophic Nutrition

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• Examiners expect the equation/events of photosynthesis, not just a definition — list all three steps.
• Specifically name guard cells when explaining stomatal action; this is a common 1-mark point.
• "Raw materials," "conditions," and "products" are separate heads — address each clearly.
• Carbohydrates not used immediately are stored as starch — worth mentioning if space allows.
• Avoid writing more than ~120 words; this answer is calibrated for 5 marks.