Describe how the structures found in a leaf are organised to allow the leaf to carry out photosynthesis efficiently. Refer to the levels of organisation in your answer.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
A leaf is a complex structure made up of different types of cells that work together to carry out photosynthesis. Scientists use the concept of levels of organisation to describe how living things are built up from smaller components.
Model answer (4 marks)
Cells are the basic unit of organisation; individual cells such as palisade mesophyll cells carry out photosynthesis.
Similar cells are grouped together to form tissues – for example, palisade mesophyll tissue and spongy mesophyll tissue.
Different tissues work together to form an organ – the leaf is the organ.
Organs work together in an organ system – the leaf is part of the shoot system of the plant, which transports water, CO₂ and sugars needed for photosynthesis.
Similar cells are grouped together to form tissues – for example, palisade mesophyll tissue and spongy mesophyll tissue.
Different tissues work together to form an organ – the leaf is the organ.
Organs work together in an organ system – the leaf is part of the shoot system of the plant, which transports water, CO₂ and sugars needed for photosynthesis.
Examiner tips
- Use the exact terms: cell, tissue, organ, organ system.
- Show the hierarchy – cells → tissues → organ → organ system.
- Mention the specific tissues (palisade, spongy) and the shoot system.
- Keep the answer concise and structured.
Common mistakes
- Confusing tissues with organs, e.g. saying ‘leaf tissue’ instead of ‘leaf organ’.
- Omitting the shoot system or plant organ system as the higher level.
- Using vague language such as ‘parts’ instead of the specific levels of organisation.
Mark scheme (4 marks)
- Cells are the basic unit of organisation; individual cells (e.g. palisade mesophyll cells) carry out photosynthesis
- Similar cells are grouped together to form tissue (e.g. palisade mesophyll tissue / spongy mesophyll tissue)
- Different tissues work together to form an organ — the leaf is the organ
- Organs work together in an organ system / the leaf is part of the shoot system / plant organ system that transports materials needed for photosynthesis
Key terms in this question
organ · levels of organisation
Related
- Revision notes: Levels of organisation →
- How to answer a "Describe" question →
- Decode the mark scheme abbreviations →
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