4.6.6Additional lessons
Pollination — IB Biology SL Revision Notes & Topical Questions
5 min read 5 parts Lesson 121 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.
Section 1 of 5Types of Pollination
Pollination is transfer of pollen from an anther to a stigma; it is not the same as fertilisation.
Self-pollination
- Self-pollination Pollen is transferred to a stigma on the same flower or another flower of the same plant, giving low genetic variation.
Cross-pollination
- Cross-pollination Pollen is transferred to a stigma of a flower on a genetically different plant of the same species, increasing variation.
Outbreeding benefit
- Outbreeding benefit Offspring from cross-pollination have a better chance of including alleles suited to changing conditions.
Prevention of selfing
- Prevention of selfing Some plants avoid self-pollination by having stamens and carpels that mature at different times,
- or male and female flowers on separate plants.
Section 2 of 5Pollinating Agents
Pollinating Agents
Insects
- Insects Bees and butterflies visit flowers for nectar or pollen, and pollen sticks to their bodies and is carried to the next flower.
Wind
- Wind Wind-pollinated plants such as grasses release huge amounts of light pollen and rely on chance to reach other stigmas.
Other animals
- Other animals Birds and bats pollinate some tropical flowers that provide large amounts of nectar.
Mutualism
- Mutualism The animal gains food and the plant gains pollination, so both species benefit from the relationship.
Section 3 of 5Insect Versus Wind Pollinated Flowers
Petals
- Petals Insect-pollinated flowers have large, coloured petals that attract insects, but wind-pollinated flowers have small, dull petals or none.
Pollen
- Pollen Insect-pollinated flowers make fewer, sticky or spiky pollen grains;
- wind-pollinated flowers produce huge numbers of small, smooth, light grains.
Stigma and anther
- Stigma and anther Wind-pollinated flowers expose feathery stigmas and dangling anthers to the air,
- but insect-pollinated ones keep them inside the flower.
Scent and nectar
- Scent and nectar Insect-pollinated flowers often produce scent and nectar that act as rewards, whereas wind-pollinated flowers do not.
| Feature | Insect-pollinated | Wind-pollinated |
|---|---|---|
| Petals | Large, colourful | Small or absent |
| Pollen quantity | Moderate | Very large |
| Pollen surface | Sticky or spiky | Smooth, light |
| Stigma | Small, inside flower | Large, feathery, exposed |
Section 4 of 5Why Pollinators Matter
1
Many crops and wild plants depend on animal pollinators to set fruit and seed.
2
A decline in insects such as bees reduces pollination and so reduces seed set and crop yields.
3
Pollinators in turn depend on flowers for food, so the loss of one partner harms the other.
4
Conserving habitats and limiting harmful pesticides therefore protects both the plants and the pollinators.
5
Farmers can support pollination by planting flowering margins and using pollinator-friendly methods.
Section 5 of 5Exam Checklist & Tips
4.6.6 – Key Points for the Exam
- Pollination Transfer of pollen from an anther to a stigma.
- Cross-pollination Transfer of pollen between flowers on different plants of the same species.
- Self-pollination Transfer of pollen within the same plant.
- Pollinator An animal that moves pollen between flowers.
- Mutualism A relationship in which both species gain a benefit.
Common Mistakes
- Writing that wind-pollinated flowers have bright petals and nectar to attract the wind.
- Using the word fertilisation when the question asks for pollination.
- Saying self-pollination gives offspring with more variation than cross-pollination.
- Forgetting to link a flower feature with how it helps pollen transfer.
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