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Ordinary Level Revision Notes
Leaving Cert Ordinary Level Biology
Chapter 14: Sexual Reproduction in Flowering Plants
Flowers, Pollination, Seeds & Germination
Subtopics Covered
- Learning Outcomes
- Big Picture: Why Flowers Matter
- Floral Structure: Main Parts
- Male and Female Reproductive Parts
- Gamete Development: HL Only Awareness
- Pollination
What This Pack Includes
- Structured chapter notes formatted for ExamsLogic website reading
- Exam-focused diagrams, definitions, and worked examples
- Interactive practice sections carried over from the source notes
- Independent study guidance based on the official curriculum
- Print-friendly layout for future PDF export when needed
This publication is an independent educational resource developed by ExamsLogic and compiled by experienced educators. It is based on publicly available official curricula, including Cambridge, Pearson Edexcel, IB, and the Irish Leaving Certificate. This product is not endorsed by, affiliated with, or sponsored by any examination board or governing authority. All registered trademarks remain the property of their respective owners.
1. Learning Outcomes
- Identify the main parts of a flower: sepals, petals, stamens and carpels.
- Describe the structure and function of the stamen: anther and filament.
- Describe the structure and function of the carpel: stigma, style and ovary.
- Distinguish between wind pollination and insect pollination.
- Explain pollination and fertilisation in flowering plants.
- Understand double fertilisation at Ordinary Level-friendly depth.
- Describe how seeds and fruits develop after fertilisation.
- Identify seed structures: testa, radicle, plumule and cotyledon.
- Describe methods of seed and fruit dispersal.
- Explain seed dormancy and the conditions needed for germination.
HL-only awareness: Microsporogenesis and megasporogenesis are Higher Level details. This Ordinary Level chapter focuses on flower structure, pollination, fertilisation, seed formation and germination.
2. Big Picture: Why Flowers Matter
Gametes
Flowers produce male and female reproductive cells needed for sexual reproduction.
Seeds
After fertilisation, ovules develop into seeds that can grow into new plants.
Dispersal
Fruits and seeds help offspring spread away from the parent plant, reducing competition.
Biology link: Flower structure is not decoration only. Each part has a reproductive function, from attracting pollinators to protecting developing seeds.
3. Floral Structure: Main Parts
| Flower part | Structure | Function |
|---|---|---|
| Sepals | Green leaf-like structures around the flower bud. | Protect the flower before it opens. |
| Petals | Often colourful structures. | Attract pollinators such as insects. |
| Stamen | Male reproductive part: anther + filament. | Produces and holds pollen. |
| Anther | Part of the stamen. | Produces pollen grains. |
| Filament | Stalk of the stamen. | Supports the anther. |
| Carpel | Female reproductive part: stigma + style + ovary. | Receives pollen and contains ovules. |
| Stigma | Sticky top of the carpel. | Receives pollen. |
| Style | Tube-like connection between stigma and ovary. | Allows pollen tube growth. |
| Ovary | Base of the carpel. | Contains ovules and later may become fruit. |
| Ovule | Structure inside ovary. | Contains female gamete and later becomes seed. |
Exam Tip: Learn flower structure in pairs: stamen = anther + filament; carpel = stigma + style + ovary.
4. Male and Female Reproductive Parts
Male part: Stamen
- Anther produces pollen grains.
- Pollen contains the male gamete/nucleus.
- Filament holds the anther in position.
Female part: Carpel
- Stigma receives pollen.
- Style connects stigma to ovary.
- Ovary contains ovules.
- Ovule contains the female gamete and becomes the seed.
Common Mistake: Saying pollen is made by the stigma. Correct: pollen is produced by the anther.
5. Gamete Development: HL Only Awareness
| Process | Where it occurs | OL treatment |
|---|---|---|
| Microsporogenesis | Anther. | Higher Level detail. OL students should know pollen is produced in anthers. |
| Megasporogenesis | Ovule inside ovary. | Higher Level detail. OL students should know ovules contain female reproductive cells. |
| Embryo sac formation | Ovule. | Higher Level detail. Not needed in full for Ordinary Level. |
HL-only note: Do not overload OL answers with microsporogenesis and megasporogenesis unless specifically asked. For Ordinary Level, focus on anthers producing pollen and ovules becoming seeds.
6. Pollination
Pollination is the transfer of pollen from an anther to a stigma.
| Type | Meaning | Result |
|---|---|---|
| Self-pollination | Pollen is transferred to a stigma of the same plant. | Less variation than cross-pollination. |
| Cross-pollination | Pollen is transferred to a stigma of another plant of the same species. | Increases genetic variation. |
Pollen made in anther→
Transferred by vector→
Lands on stigma→
Pollen tube grows
Examiner Secret: Pollination is not the same as fertilisation. Pollination is pollen transfer; fertilisation is fusion of gametes.
7. Wind vs Insect Pollination
| Feature | Wind-pollinated flowers | Insect-pollinated flowers |
|---|---|---|
| Petals | Small, dull or absent. | Large, colourful and attractive. |
| Nectar/scent | Usually absent. | Often present. |
| Pollen | Light, smooth and produced in large amounts. | Sticky/spiky and produced in smaller amounts. |
| Anthers | Often hang outside flower. | Usually inside flower. |
| Stigma | Large, feathery and outside flower to catch pollen. | Sticky and inside flower. |
| Vector | Wind. | Insects such as bees. |
Exam Tip: Comparison questions are easier in a table. Match feature to feature: pollen, stigma, petals, nectar and vector.
8. Fertilisation in Flowering Plants
After pollen lands on a suitable stigma, a pollen tube grows down through the style toward the ovary. The male nucleus travels down the pollen tube to the ovule.
Pollen on stigma→
Pollen tube grows→
Male nucleus travels→
Male + female gametes fuse→
Zygote forms
| Term | Meaning |
|---|---|
| Fertilisation | Fusion of male and female gametes/nuclei to form a zygote. |
| Zygote | First cell of the new organism after fertilisation. |
| Embryo | Young developing plant inside the seed. |
Examiner Trap: Fertilisation happens in the ovule, not on the stigma. The stigma receives pollen first.
9. Double Fertilisation
In flowering plants, fertilisation is special because two fertilisation events occur.
| Event | Result | Importance |
|---|---|---|
| Male gamete/nucleus fuses with egg cell | Zygote forms. | Zygote develops into embryo. |
| Another male nucleus fuses with polar nuclei | Endosperm forms. | Endosperm provides food for developing embryo. |
Double fertilisation → zygote + endosperm
OL-friendly version: Remember the outcomes: zygote becomes embryo, endosperm is food supply.
10. Seed and Fruit Development
After fertilisation, flower parts change into seed and fruit structures.
| Before fertilisation | After fertilisation |
|---|---|
| Ovule | Seed |
| Ovary | Fruit |
| Zygote | Embryo |
| Ovule wall | Seed coat/testa |
| Petals, stamens and sepals | Often wither and fall away. |
Examiner Secret: The two most important transformation facts are: ovule → seed and ovary → fruit.
11. Seed Structure
| Seed part | Function |
|---|---|
| Testa | Protective seed coat. |
| Radicle | Embryonic root. |
| Plumule | Embryonic shoot. |
| Cotyledon | Seed leaf; often stores food or absorbs food. |
| Embryo | Young plant inside the seed. |
| Micropyle | Small opening where water may enter during germination. |
Exam Tip: Radicle = root. Plumule = shoot. That memory link is gold in seed questions.
12. Seed and Fruit Dispersal
Dispersal is the spreading of seeds or fruits away from the parent plant.
| Dispersal method | Adaptation | Example idea |
|---|---|---|
| Wind | Light seeds, wings or parachute hairs. | Dandelion-like seeds. |
| Animals | Fleshy fruit eaten by animals or hooks sticking to fur. | Berries or burrs. |
| Water | Floating fruits/seeds with waterproof coverings. | Coconut-like examples. |
| Self-explosive | Pods burst open and throw seeds. | Pea-family style pods. |
Examiner Trap: Dispersal reduces competition with the parent plant. Do not just say “so seeds move.” Explain the advantage.
13. Seed Dormancy
Dormancy is a period when a seed is alive but not actively growing.
| Dormancy factor | How it affects germination |
|---|---|
| Hard seed coat/testa | May prevent water or oxygen entering. |
| Lack of water | Metabolic reactions cannot start. |
| Unsuitable temperature | Enzymes may not work well. |
| Lack of oxygen | Respiration cannot supply enough energy. |
| Chemical inhibitors | May prevent germination until conditions improve. |
Examiner Secret: Dormancy helps seeds survive bad conditions and germinate when conditions are suitable.
14. Germination Requirements
Germination is the beginning of growth of a seed into a new plant.
| Requirement | Why it is needed |
|---|---|
| Water | Activates enzymes, softens testa and allows reactions to occur. |
| Oxygen | Needed for aerobic respiration to release energy. |
| Suitable temperature | Allows enzymes to work efficiently. |
Water absorbed→
Enzymes activated→
Stored food broken down→
Respiration releases energy→
Radicle emerges
Exam Tip: Germination requirements are water, oxygen and suitable temperature. Light is not always required for germination.
15. Interactive Simulator: Flower Part Detective
Identify the Flower Part
Clue: Produces pollen grains.
Feedback
Ready
Match the part to its function.
16. Interactive Simulator: Pollination and Seed Development
Choose the Correct Outcome
Prompt: After fertilisation, the ovule becomes...
Feedback
Ready
Remember: ovule → seed and ovary → fruit.
17. High-Value Exam Guidance
Exam Tip 1: Pollination = transfer of pollen from anther to stigma.
Exam Tip 2: Fertilisation = fusion of male and female gametes/nuclei.
Exam Tip 3: Ovule becomes seed; ovary becomes fruit.
Exam Tip 4: Germination needs water, oxygen and suitable temperature.
Examiner Trap 1: Do not confuse anther and stigma. Anther produces pollen; stigma receives pollen.
Examiner Trap 2: Double fertilisation produces zygote and endosperm, not two identical seeds.
Examiner Trap 3: Seed dispersal is not the same as pollination. Pollination transfers pollen; dispersal spreads seeds/fruits.
Common Mistake 1: Saying the seed becomes the fruit. Correct: ovule becomes seed; ovary becomes fruit.
Common Mistake 2: Saying all flowers are insect-pollinated. Some are wind-pollinated.
Examiner Secret 1: For wind vs insect pollination, pollen type and stigma type are high-value comparison points.
Examiner Secret 2: Radicle becomes root; plumule becomes shoot.
Examiner Secret 3: Dormancy is useful because it delays germination until conditions improve.
18. MCQs with Instant Answers
1. Pollen is produced by the:
Answer: A. The anther produces pollen grains.
2. The stigma is mainly used to:
Answer: A. The stigma receives pollen during pollination.
3. Pollination is:
Answer: B. Pollination is pollen transfer from anther to stigma.
4. Fertilisation is:
Answer: A. Fertilisation is the fusion of male and female gametes/nuclei.
5. After fertilisation, the ovule becomes the:
Answer: A. The ovule develops into the seed.
6. After fertilisation, the ovary becomes the:
Answer: A. The ovary develops into the fruit.
7. The testa is the:
Answer: A. The testa is the protective seed coat.
8. The radicle develops into the:
Answer: A. The radicle is the embryonic root.
9. Germination usually requires:
Answer: A. Seeds need water, oxygen and suitable temperature for germination.
10. Wind-pollinated flowers usually have:
Answer: A. Wind-pollinated flowers often have light pollen and feathery stigmas.
19. Structured Exam Questions
- Draw and label a flower, including sepals, petals, anther, filament, stigma, style and ovary. [8]
- State the function of each of the following: sepal, petal, anther, stigma and ovary. [10]
- Define pollination and distinguish between self-pollination and cross-pollination. [6]
- Compare wind-pollinated and insect-pollinated flowers under five headings. [10]
- Describe the events from pollination to fertilisation. [7]
- Explain double fertilisation and state the two products formed. [4]
- State what the ovule and ovary become after fertilisation. [4]
- Draw and label a seed showing testa, radicle, plumule and cotyledon. [6]
- Describe four methods of seed or fruit dispersal. [8]
- Explain seed dormancy and give two factors that can maintain dormancy. [5]
- State the requirements for germination and explain why each is needed. [6]
20. Detailed Mark Scheme
Q1. Correct flower diagram [1]. Labels: sepal [1], petal [1], anther [1], filament [1], stigma [1], style [1], ovary [1].
Q2. Sepal protects bud [2]. Petal attracts pollinators [2]. Anther produces pollen [2]. Stigma receives pollen [2]. Ovary contains ovules/develops into fruit [2].
Q3. Pollination is transfer of pollen from anther to stigma [2]. Self-pollination is transfer within same plant [2]. Cross-pollination is transfer to another plant of same species [2].
Q4. Wind: dull petals/no scent/no nectar/light pollen/feathery stigma/anthers outside [1 each]. Insect: colourful petals/scent/nectar/sticky pollen/sticky stigma/anthers inside [1 each]. Max 10 for matched comparison.
Q5. Pollen lands on stigma [1]. Pollen tube grows through style [1]. Male nucleus travels down tube [1]. Tube reaches ovule [1]. Male and female gametes/nuclei fuse [2]. Zygote forms [1].
Q6. Double fertilisation involves two fusion events [1]. One produces zygote [1]. Another produces endosperm [1]. Endosperm provides food for embryo [1].
Q7. Ovule becomes seed [2]. Ovary becomes fruit [2].
Q8. Correct seed diagram [2]. Labels: testa [1], radicle [1], plumule [1], cotyledon [1].
Q9. Wind: light/winged/hairy seeds [2]. Animals: fleshy fruit/hooks [2]. Water: floating/waterproof seeds/fruits [2]. Explosive/self: pods burst and scatter seeds [2].
Q10. Dormancy is a period when seed is alive but not actively growing [2]. Factors: hard testa [1], lack of water [1], unsuitable temperature [1], lack of oxygen [1], chemical inhibitors [1]. Max 5.
Q11. Water activates enzymes/softens testa [2]. Oxygen needed for respiration [2]. Suitable temperature needed for enzyme activity [2].
Q2. Sepal protects bud [2]. Petal attracts pollinators [2]. Anther produces pollen [2]. Stigma receives pollen [2]. Ovary contains ovules/develops into fruit [2].
Q3. Pollination is transfer of pollen from anther to stigma [2]. Self-pollination is transfer within same plant [2]. Cross-pollination is transfer to another plant of same species [2].
Q4. Wind: dull petals/no scent/no nectar/light pollen/feathery stigma/anthers outside [1 each]. Insect: colourful petals/scent/nectar/sticky pollen/sticky stigma/anthers inside [1 each]. Max 10 for matched comparison.
Q5. Pollen lands on stigma [1]. Pollen tube grows through style [1]. Male nucleus travels down tube [1]. Tube reaches ovule [1]. Male and female gametes/nuclei fuse [2]. Zygote forms [1].
Q6. Double fertilisation involves two fusion events [1]. One produces zygote [1]. Another produces endosperm [1]. Endosperm provides food for embryo [1].
Q7. Ovule becomes seed [2]. Ovary becomes fruit [2].
Q8. Correct seed diagram [2]. Labels: testa [1], radicle [1], plumule [1], cotyledon [1].
Q9. Wind: light/winged/hairy seeds [2]. Animals: fleshy fruit/hooks [2]. Water: floating/waterproof seeds/fruits [2]. Explosive/self: pods burst and scatter seeds [2].
Q10. Dormancy is a period when seed is alive but not actively growing [2]. Factors: hard testa [1], lack of water [1], unsuitable temperature [1], lack of oxygen [1], chemical inhibitors [1]. Max 5.
Q11. Water activates enzymes/softens testa [2]. Oxygen needed for respiration [2]. Suitable temperature needed for enzyme activity [2].
21. Mastery Checklist
- I can label a flower accurately.
- I can state the function of sepals, petals, stamens and carpels.
- I can define pollination.
- I can distinguish pollination and fertilisation.
- I can compare wind and insect pollination.
- I can describe pollen tube growth.
- I can explain double fertilisation at OL standard.
- I know that ovule becomes seed and ovary becomes fruit.
- I can label seed parts: testa, radicle, plumule and cotyledon.
- I can describe seed dispersal methods.
- I can explain dormancy.
- I can state and explain germination requirements.