Photosynthesis is the process by which plants make their own food. Explain how the raw materials for photosynthesis are obtained by a plant and how they are used to produce glucose.

Pearson Edexcel A-Level Biology A (9BI0) — 3.1 Photosynthesis · Explain · 5 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Plants are described as producers because they can manufacture organic molecules from inorganic substances using light energy.

Model answer (5 marks)

Carbon dioxide is absorbed through the stomata in the leaves.
Water is taken up by the roots from the soil and transported to the leaves.
Light energy is captured by chlorophyll in the chloroplasts.
The absorbed CO₂ and H₂O are converted into glucose (C₆H₁₂O₆) and oxygen.
Oxygen is released as a by‑product through the stomata.

Examiner tips

  • Use the exact terms: stomata, chlorophyll, chloroplasts, glucose, oxygen.
  • Show the flow: CO₂ + H₂O + light → glucose + O₂.
  • Remember to mention the source of each raw material (soil, atmosphere).

Common mistakes

  • Confusing stomata with pores or stomata with stomata; not specifying leaves. Omitting the role of chlorophyll or chloroplasts. Failing to state that oxygen is released through the stomata.

Mark scheme (5 marks)

  1. Carbon dioxide is absorbed / taken in through the stomata (in the leaves)
  2. Water is absorbed from the soil by the roots (and transported to the leaves)
  3. Light energy is absorbed / captured by chlorophyll (in the chloroplasts)
  4. Carbon dioxide and water are converted / used to produce glucose (and oxygen)
  5. Oxygen is released as a by-product of photosynthesis (through the stomata)

Key terms in this question

photosynthesis · glucose

Related

More Photosynthesis questions

▶ Try answering this question with AI marking (free) →