2.9.5Inquiry Process
Biomes — IB Biology HL Revision Notes & Topical Questions
5 min read 4 parts Lesson 96 of 160
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.
Section 1 of 4Major Biomes and Climates
Tropical forest
- Tropical forest Rainfall of about 2000 to 10 000 mm and steady temperatures of 20 to 25 °C support layered vegetation, very high productivity and very high biodiversity.
Temperate forest
- Temperate forest Moderate rainfall of about 750 to 1500 mm and seasonal temperatures support deciduous trees, fertile soils from autumn leaf fall and high biodiversity.
Taiga
- Taiga Cold winters, a short summer growing season and rainfall of about 300 to 900 mm favour evergreen conifers and low productivity.
Grassland
- Grassland Rainfall of about 500 to 950 mm with wet and dry seasons favours grasses and grazers, but there is too little water for many trees.
Tundra
- Tundra Frozen soil, dark winters and little rainfall prevent tree growth, so productivity is low and many animals hibernate or migrate.
Hot desert
- Hot desert Less than about 250 mm of rain and large temperature swings between day and night give very low productivity and few well-adapted species.
| Biome | Rainfall (mm per year) | Productivity |
|---|---|---|
| Tropical forest | 2000 to 10 000 | Very high |
| Temperate forest | 750 to 1500 | High in growing season |
| Grassland | 500 to 950 | Low to moderate |
| Tundra | 150 to 250 | Low |
| Hot desert | Below 250 | Very low |
Section 2 of 4Convergent Evolution in Biomes
1
Regions of the world with similar abiotic factors develop the same biome, for example hot deserts in Africa, the Americas and Australia.
2
Species in separate deserts face similar selection pressures, such as heat and shortage of water.
3
Individuals with features that conserve water survive better and leave more offspring, so those features become common through natural selection.
4
The resulting communities look alike even though the species are not close relatives and did not inherit the features from a recent common ancestor.
5
Spines and succulent stems in South American cacti and African euphorbias are a standard example of this convergent evolution.
Section 3 of 4Adaptations in Desert and Rainforest
Adaptations in Desert and Rainforest
Saguaro cactus
- Saguaro cactus A thick waxy stem, spines instead of leaves, expandable water-storing cells and both deep and shallow roots all help it conserve and gather water.
Kangaroo rat
- Kangaroo rat It avoids daytime heat by staying in a burrow, gets water from its food and produces very concentrated urine,
- so it rarely needs to drink.
Kapok tree
- Kapok tree Fast growth lets it reach the sunlit canopy before competitors, and wide buttress roots support its great height.
Orchid mantis
- Orchid mantis The female resembles an orchid flower, an aggressive mimic that attracts insect prey, while the smaller male is camouflaged among stems.
Adaptation
- Adaptation A trait that raises survival chances in a given environment and spreads through a population by natural selection.
Section 4 of 4Exam Checklist & Tips
2.9.5 – Key Points for the Exam
- Biome A large community of plants and animals shaped by environmental factors.
- Convergent evolution Independent evolution of similar features in unrelated species facing similar selection pressures.
- Adaptation A characteristic that increases the chance of survival in a particular environment.
- Mimicry A resemblance of one organism to another organism or object that gives an advantage.
Common Mistakes
- Saying that desert species in different continents are close relatives because they look alike.
- Describing adaptations as organisms choosing to change;
- they arise through natural selection acting on variation.
- Stating that a tropical rainforest has rich soil;
- nutrients are held in living biomass and the soil is often poor.
- Forgetting to state both the feature and how it helps survival when asked for an adaptation.
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