Science — AI-generated practice question

Necessary conditions for autotrophic nutrition (photosynthesis):

1. Carbon dioxide and water – raw materials taken from the environment.
2. Chlorophyll – the green pigment that absorbs light energy.
3. Sunlight – the external energy source for the reaction.

These are used to synthesise carbohydrates (glucose/starch) from CO₂ and water.

Byproducts:

• Oxygen is released during the splitting of water molecules.
• Water is also produced as a byproduct of the reaction.

The carbohydrates not immediately used are stored as starch.

Source: Chapter 5, Section 5.2.1 Autotrophic Nutrition

---

Examiners look for all three necessary conditions (CO₂ + water, chlorophyll, sunlight) and oxygen as the main byproduct — that alone can fetch 2 marks. The third mark often goes to mentioning carbohydrates/starch as the product and oxygen from water-splitting as the key byproduct. Question 3 in the exercises directly hints that "all of the above" (CO₂, water, chlorophyll, sunlight) are required — use that as a memory anchor.