IB MYP 4-5 Biology-Reproduction- Study Notes - New Syllabus
IB MYP 4-5 Biology-Reproduction- Study Notes – New syllabus
IB MYP 4-5 Biology-Reproduction- Study Notes – IB MYP 4-5 Biology – per latest IB MYP Biology Syllabus.
Key Concepts:
- Asexual vs sexual reproduction
- Advantages of each method
- Flower structure and pollination
Reproduction
What is Reproduction?
Reproduction is the process by which living organisms produce new individuals of their own kind. It ensures that life continues from one generation to the next.
There are two main types of reproduction:
- Asexual reproduction
- Sexual reproduction
Asexual Reproduction – One Parent Only
Key Features:
- Involves only one parent
- Offspring are genetically identical (clones)
- No gametes (sex cells) involved
- Quick and energy-efficient
How It Happens:
- Simple cell division (e.g. binary fission in bacteria)
- Budding (e.g. in yeast or hydra)
- Fragmentation (e.g. in flatworms)
- Vegetative propagation (in plants – like potato tubers)
Sexual Reproduction – Two Parents, Mixed Genes
Key Features:
- Involves two parents
- Male and female gametes (sperm and egg) fuse during fertilization
- Offspring are genetically different
- Promotes variation and diversity
Process:
- Meiosis creates gametes with half the chromosomes
- Fertilization restores full chromosome number
- The zygote grows into a new individual
Asexual vs Sexual Reproduction
| Feature | Asexual Reproduction | Sexual Reproduction |
|---|---|---|
| Number of parents | One | Two |
| Gametes involved? | No | Yes (sperm + egg) |
| Genetic variation | No – clones | Yes – offspring are unique |
| Speed | Fast | Slower process |
| Energy use | Low | High (gamete production, mating, etc.) |
| Examples | Bacteria, potato, hydra | Humans, birds, flowering plants |
| Adaptability | Low – all individuals are similar | High – more variation means better survival chances |
Why It Matters in Nature
- Asexual Reproduction is useful when:
- Conditions are stable
- Rapid population growth is needed
- Organisms are simple (like microbes or simple plants)
- Sexual Reproduction is better when:
- Conditions change often
- Species need to adapt
- Long-term survival and evolution are important
Know the Difference:
| Asexual Reproduction | Sexual Reproduction |
|---|---|
| 1 parent | 2 parents |
| No variation | Lots of variation |
| Fast and simple | Complex but adaptive |
| Clones | Genetically unique |
Reproduction keeps life going.
Asexual is fast and identical.
Sexual is slower but creates diversity – essential for evolution.
Advantages of Asexual and Sexual Reproduction
Advantages of Asexual Reproduction
Asexual reproduction is simple, fast, and effective, especially in stable environments.
Faster Reproduction: Organisms can reproduce quickly without waiting for a mate. Ideal for bacteria, fungi, and fast-growing species.
Only One Parent Needed: No energy or time spent finding a partner – useful for isolated organisms.
Large Numbers of Offspring: Populations grow rapidly – helpful for colonizing new areas.
Exact Copies (Clones): Offspring have identical traits – beneficial if parent is well-adapted.
Less Energy Used: No gametes or mating – energy is saved and used for reproduction.
Advantages of Sexual Reproduction
Sexual reproduction takes more effort but offers better survival in changing environments.
Genetic Variation: Offspring are genetically unique increases chances of surviving diseases or climate changes.
Better Adaptation: Variation leads to survival of the fittest in harsh conditions.
Reduces Risk of Inherited Diseases: Harmful genes are diluted, lowering the risk of inherited disorders.
Supports Natural Selection: Provides raw material for evolution better adaptation over time.
Summary Table – Advantages of Each Method
| Asexual Reproduction | Sexual Reproduction |
|---|---|
| Fast and simple | Slower, but allows mixing of genes |
| One parent is enough | Needs two parents |
| Produces large numbers quickly | Produces fewer, but unique offspring |
| No variation – all are clones | Genetic variation in every generation |
| Great in stable conditions | Great in changing environments |
| Less energy used | More energy needed (gametes, mating) |
Flower Structure and Pollination
What Is a Flower?
- A flower is the reproductive organ of a plant. It contains the structures needed to make seeds through pollination and fertilization.
- Flowers are not just pretty – they’re smart designs to attract pollinators and ensure the plant species continues.
Main Parts of a Flower
| Part | Function |
|---|---|
| Petals | Brightly colored to attract insects and birds |
| Sepals | Protect the flower bud |
| Stamens | Male part – produces pollen (contains male gametes) |
| Anther | Makes and stores pollen |
| Filament | Holds up the anther |
| Carpel / Pistil | Female part – contains ovary |
| Stigma | Sticky top where pollen lands |
| Style | Tube that connects stigma to ovary |
| Ovary | Contains ovules (female gametes) |
Male part = Stamen → Anther + Filament
Female part = Carpel → Stigma + Style + Ovary
What Is Pollination?
Pollination is the transfer of pollen from the anther to the stigma. It’s the first step in fertilization, allowing the male gamete to reach the female ovule.
Types of Pollination
| Type | Description |
|---|---|
| Self-pollination | Pollen goes to the stigma of the same flower or same plant |
| Cross-pollination | Pollen travels to the stigma of another plant of the same species |
Pollination Agents
Plants can’t move, so pollen is transferred using pollinators or natural forces.
| Agent | How It Works | Example Flowers |
|---|---|---|
| Insects | Pollen sticks to their body as they feed | Roses, lilies |
| Wind | Light, dry pollen carried in air | Grass, wheat |
| Water | Pollen floats to other flowers | Some aquatic plants |
| Animals/Birds | Carry pollen on beaks or fur | Bright tropical flowers |
Adapting to Pollination Types
| Pollination Type | Flower Adaptations |
|---|---|
| Insect-pollinated | Bright colors, nectar, scent, sticky pollen |
| Wind-pollinated | Small petals, no scent, lots of light pollen, exposed anthers/stigmas |