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4.1Ecology and the Environment

The organism in the environment — Edexcel Modular - OL Revision Notes & Topical Questions

10 min read 16 parts Lesson 2 of 5 2 quizzes

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Lesson summary

The organism in the environment Edexcel O Level Modular Biology notes: understand the terms population, community, habitat and ecosystemTwo species cannot share exactly the same niche for long (competitive exclusion).Biomestundra, desert, rainforest, grassland, taiga, deciduous f…

  • The organism in the environment Edexcel O Level Modular Biology: what to do next
  • Give / State / Name
  • Evaluate / Assess
  • Keywords the mark scheme looks for in this lesson
  • How to get full marks (examiner guidance)
  • Link ideas

Part 1 of 6Key ideas

Two species cannot share exactly the same niche for long (competitive exclusion).
Biomes
Biomes tundra, desert, rainforest, grassland, taiga, deciduous forest.

Part 2 of 6Syllabus points

Syllabus points
understand the terms population, community, habitat and ecosystem
practical: investigate the population size of an organism in two different areas using quadrats practical: investigate the distribution of organisms in their habitats and measure biodiversity using quadrats
understand how abiotic and biotic factors affect the population size and distribution of organisms

Part 3 of 6Process & sequence

  • Organism
  • Population
  • Community
  • Ecosystem
  • Biome
  • Biosphere
Factors
Biotic predators, competitors, food
Abiotic temperature, water, light, soil

Part 4 of 6Summary

Summary
Community + abiotic factors = ecosystem.
An organism’s role is its niche.

Part 5 of 6Keep going

The organism in the environment Edexcel O Level Modular Biology: what to do next

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

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Practice: The organism in the environment Edexcel O Level Modular Biology practice questions
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Previous lesson: 3.2 Inheritance — Notes
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Next lesson: 4.2 Feeding relationships — Notes
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Course: Edexcel Modular - OL — all units
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Official syllabus: Pearson Edexcel International GCSEs

The organism in the environment Edexcel O Level Modular Biology revision notes

Part 6 of 6Compare: Compare

Levels of ecological organisation
LevelIncludesExampleLiving only?ScaleStudy focus
OrganismOne individualOne lionYesSmallestAdaptations
PopulationOne speciesLions in SerengetiYes—Growth, density
CommunityAll speciesLions, zebras, grassYes—Interactions
EcosystemCommunity + abioticSerengeti plainsNo—Energy, cycles
BiomeSimilar ecosystemsSavannaNo—Climate
BiosphereAll life on EarthEarthNoLargestGlobal change

Key terms

Command 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.

Exam technique

Keywords the mark scheme looks for in this lesson

Keywords the mark scheme looks for in this lesson
Organism · Population · Community · Ecosystem · Biome · Biosphere · Habitat · Niche
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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