2.8.5Additional lessons
Biomes — IB Biology SL Revision Notes & Topical Questions
5 min read 6 parts Lesson 45 of 142
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
Part 1 of 6What a Biome Is
Biome
- Biome A group of ecosystems in different regions with a similar climate and similar plant and animal types.
Climate
- Climate The two main factors controlling biome distribution are temperature and rainfall.
Vegetation
- Vegetation The dominant vegetation, such as forest, grass or shrub, is a major feature used to describe a biome.
Latitude and altitude
- Latitude and altitude Climate changes with distance from the equator and height above sea level, so biomes change with these.
Climate graphs
- Climate graphs A climograph plots mean monthly temperature and rainfall to show the pattern of a biome.
Part 2 of 6Examples of Biomes
Examples of Biomes
Tropical rainforest
- Tropical rainforest Warm all year with high rainfall, supporting dense forest and very high biodiversity.
Desert
- Desert Very low rainfall, so plants and animals have adaptations to conserve water.
Tundra
- Tundra Cold, with a frozen layer of soil called permafrost, so only low-growing plants survive.
Temperate forest
- Temperate forest Moderate temperatures and rainfall with distinct seasons support deciduous trees.
Grassland
- Grassland Moderate rainfall, often with grazing animals, supports grasses rather than trees.
| Biome | Temperature | Rainfall |
|---|---|---|
| Tropical rainforest | High all year | High |
| Desert | Hot or cold depending on location | Very low |
| Tundra | Very low | Low |
| Temperate forest | Moderate, seasonal | Moderate |
Part 3 of 6Convergent Evolution
1
Unrelated species living in separate regions with similar biomes face similar selection pressures.
2
Natural selection favours similar features in their different gene pools.
3
Over generations they develop similar adaptations, such as water-storing stems in desert plants.
4
This is convergent evolution: similar structures that evolved independently, not from a common ancestor in that biome.
Part 4 of 6Biomes and Change
Biomes and Change
Climate change
- Climate change Changing temperature and rainfall patterns can shift the boundaries of biomes over time.
Biodiversity
- Biodiversity Biomes differ in species richness; tropical rainforests contain far more species than tundra.
Human impact
- Human impact Clearing forest or ploughing grassland for agriculture changes the biome in a region.
Part 5 of 6Comparing Two Biomes
Comparing Two Biomes
Rainforest
- Rainforest Rainfall is high and temperatures are warm, so plants grow all year and form several layers.
Tundra
- Tundra Low temperatures and a short growing season limit the growth of plants to small, ground-hugging species.
Reason
- Reason The difference in temperature and rainfall explains the difference in vegetation and animal life.
Part 6 of 6Exam Checklist & Tips
2.8.5 – Key Points for the Exam
- Biome A large group of ecosystems with similar climate and organisms.
- Climograph A graph of temperature and rainfall for a location.
- Convergent evolution Unrelated species evolving similar features because of similar environments.
- Permafrost Permanently frozen soil found in tundra.
Common Mistakes
- Using biome and habitat as if they were the same; a biome is much larger and groups many ecosystems.
- Thinking that species in the same biome must be closely related.
- Saying that biome distribution depends only on latitude, ignoring altitude and ocean currents.
- Describing deserts as always hot; some are cold but dry.
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