4.7.5Additional lessons
Plant Reproduction — IB Biology HL Revision Notes & Topical Questions
5 min read 5 parts Lesson 59 of 101
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 5Flower Structure
A typical flower has both male and female parts arranged in rings.
Sepals and petals
- Sepals and petals Sepals protect the bud, and petals are often large or coloured to attract pollinators.
Stamen
- Stamen The male part: an anther that produces pollen grains containing male gametes, on a filament.
Carpel
- Carpel The female part: a stigma that receives pollen, a style, and an ovary containing ovules.
Ovule
- Ovule Contains the female gamete, and after fertilisation develops into a seed.
Section 2 of 5From Pollen to Seed
1
Pollen is transferred from an anther to a stigma, a process called pollination.
2
A pollen grain germinates on the stigma and grows a pollen tube down the style towards an ovule.
3
The male gamete travels down the pollen tube and fuses with the female gamete in the ovule, which is fertilisation.
4
The fertilised ovule develops into a seed, and the ovary wall develops into a fruit.
Section 3 of 5Asexual Reproduction in Plants
Runners
- Runners Horizontal stems grow from the parent and form new plants at nodes, as in strawberry.
Tubers and bulbs
- Tubers and bulbs Underground storage organs, such as potato tubers, produce new shoots that become separate plants.
Cuttings
- Cuttings Gardeners can grow new plants from stem pieces, creating clones of the parent.
Advantage
- Advantage Offspring are produced without pollinators or seed, and food reserves help them establish quickly.
| Feature | Sexual | Asexual |
|---|---|---|
| Variation | High | None (clone) |
| Needs pollinator | Often | No |
| Spread | Seeds can travel far | Usually short distance |
Section 4 of 5Reproductive Strategy
Combined strategy
- Combined strategy Many plants use both, spreading widely by seed while expanding locally by runners.
Seeds
- Seeds They provide dormancy and dispersal, helping the species survive harsh seasons.
Fruit
- Fruit Protects seeds and helps dispersal by animals or wind.
Section 5 of 5Exam Checklist & Tips
4.7.5 – Key Points for the Exam
- Pollination The transfer of pollen from an anther to a stigma.
- Pollen tube A tube growing from a pollen grain down the style to the ovule.
- Ovule The structure in the ovary that becomes a seed after fertilisation.
- Carpel The female reproductive structure of a flower, made of stigma, style and ovary.
Common Mistakes
- Mixing up pollination (transfer of pollen) with fertilisation (fusion of gametes).
- Saying that the ovary becomes the seed; the ovule becomes the seed.
- Placing the anther on the carpel.
- Labelling the stigma as the male structure.
Last updated:
\n