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2.1Structures and Functions in Living Organisms

Level of organisation — Edexcel Modular - OL Revision Notes & Topical Questions

5 min read 7 parts Lesson 1 of 12 2 quizzes

📚 Edexcel Modular - OL Hub / Topical Revision
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Lesson summary

Level of organisation Edexcel O Level Modular Biology notes: describe the levels of organisation in organismsThe order is always cell → tissue → organ → organ system → organism.A tissue contains only one type of cell; an organ contains several tissues.The heart is an organ; the c…

  • Plants have organs too
  • Level of organisation Edexcel O Level Modular Biology: what to do next
  • Muscle tissue
  • Circulatory system
  • Give / State / Name
  • Evaluate / Assess

Section 1 of 7Process & sequence

  • Cell
  • Tissue
  • Organ
  • Organ system
  • Organism
1Cells
Similar cells group together to form a tissue.
2Organ
Different tissues join to form an organ.
3Organ system
Organs work together as an organ system.
4Organism
All organ systems together make an organism.

Section 2 of 7Keep going

Level of organisation Edexcel O Level Modular Biology: what to do next

These Level of organisation Edexcel O Level Modular Biology notes covered the key ideas, worked examples and exam technique for this topic. Check your Level of organisation Edexcel O Level Modular Biology understanding with the practice questions below, then reread any Level of organisation Edexcel O Level Modular Biology point you were unsure about before moving on.

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Practice: Level of organisation Edexcel O Level Modular Biology practice questions
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Previous lesson: 1.2 Variety of living organisms — Notes
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Next lesson: 2.2 Cell structure — Notes
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Course: Edexcel Modular - OL — all units
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Official syllabus: Pearson Edexcel International GCSEs

Level of organisation Edexcel O Level Modular Biology revision notes

Section 3 of 7Compare

Levels of organisation
LevelMade ofAnimal examplePlant exampleJob of the exampleSize
CellOrganelles (nucleus, membrane…)Muscle cellPalisade cellContract / photosynthesiseMicroscopic
TissueSimilar cellsMuscle tissueXylem tissueMove body parts / carry waterVery small
OrganDifferent tissuesHeart, stomachLeaf, rootPump blood / make foodVisible
Organ systemSeveral organsCirculatory systemShoot systemTransport around body / plantLarge
OrganismOrgan systemsHumanSunflowerCarries out all life processesWhole living thing

Section 4 of 7Key terms

Section 5 of 7Syllabus checklist

  1. describe the levels of organisation in organisms
    • organelles, cells
    • tissues
    • organs and systems

Section 6 of 7Command terms

Command terms
Give / State / Name
Recall a fact; one idea per mark.
Define
Give the exact meaning using the specification keywords.
Describe
Give an account of what happens / the pattern in data, quoting values; no reasons needed.
Explain
Give reasons with linked statements (cause → effect). Each linked step is usually a separate marking point.
Suggest
Use knowledge in a new context; more than one answer may be accepted.
Compare
Similarities and differences; each point must refer to both items.
Calculate
Show working; include units; check significant figures. Method marks are given even if the final answer is wrong.
Discuss
Explore the issue from different angles and link the points.
Evaluate / Assess
Weigh strengths and weaknesses and reach a supported judgement.
Deduce
Draw a conclusion from the information given.
Justify
Support a statement/choice with evidence.

Section 7 of 7Exam technique

Keywords the mark scheme looks for in this lesson

Keywords the mark scheme looks for in this lesson
Cell · Tissue · Organ · Organ system · Organism · Muscle tissue · Xylem · Circulatory system
Learn each definition in the Key words tab exactly; a missing keyword in a definition usually loses the mark.

How to get full marks (examiner guidance)

How to get full marks (examiner guidance)
Use specification keywords exactly (e.g. eukaryotic/prokaryotic, enzyme–substrate complex, active site, complementary).
Link ideas
Link ideas for “explain” each marking point is usually a cause → consequence step; unlinked facts often score nothing.
Use the information in the question
“discuss/evaluate” answers must use the data provided and match the number of marks.
Convert units carefully (mg → g, cm³ → dm³) and show working for calculations.
Avoid vague words
“it”, “stuff”, “things”, “goes up”, “energy is made”. Name the substance and the process.
Do not extrapolate a graph line beyond the data or to zero unless asked.
Six-mark extended responses are marked on content AND a logical, linked line of reasoning.

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