BY2 - Reproductive Strategies
- Created by: beth-marie2511
- Created on: 19-03-16 13:06
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- BY2 - Reproductive Strategies
- Asexual Reproduction
- Produces offspring genetically identical to the parent.
- Offspring are clones.
- One Parent
- Mitosis
- Disadvantage
- If conditions change individuals in the species may die because they are unable to adapt.
- No genetic variation
- e.g. Amoeba
- Produces offspring genetically identical to the parent.
- Sexual Reproduction
- Produces offspring genetically different to the parents.
- Genetic variation
- Two parents
- Gametes produced by meiosis.
- Advantage
- Seeds/sperm/larvae allow dispersal.
- Genetic variation allows a species to adapt to and survive an environmental change.
- Development of a resistance stage in the life cycle which allows a species to survive adverse conditions.
- Disadvantage
- Slower than asexual reproduction.
- Produces offspring genetically different to the parents.
- Gamete Production
- Diploid (2n)
- Full chromosome number.
- Body/Somatic cells.
- Haploid (n)
- Half the chromosome number.
- Found in the gametes (sex cells)
- Produced by meiosis.
- Half the chromosome number.
- Adult Diploid (2n)
- Meiosis
- Gametes (n)
- Gametes (n)
- Zygote (2n)
- Mitosis
- Adult Diploid (2n)
- Meiosis
- Gametes (n)
- Gametes (n)
- Zygote (2n)
- Mitosis
- Mitosis
- Zygote (2n)
- Meiosis
- Adult Diploid (2n)
- Mitosis
- Zygote (2n)
- Meiosis
- Diploid (2n)
- Ferilisation
- 1. Haploid sperm cell fuses with the haploid egg cell.
- 2. Produces diploid fertilised egg.
- 3. Mitosis takes place.
- 4. Zygote forms.
- 3. Mitosis takes place.
- 2. Produces diploid fertilised egg.
- Internal Fertilisation
- Terrestrial organisms
- Male gamete becomes independent of the need for water.
- DEFINITION: The joining together of gametes.
- OR: The fusing together of sperm and eggs inside the females body.
- Advantages
- Less gametes produced (greater chance of them meeting)
- Less chance of gametes being wasted.
- Gametes independent of water.
- Egg remains nourished and develops inside female because its enclosed in a protective layer.
- Terrestrial organisms
- External Fertilisation
- Aquatic organisms release their gametes directly into the sea/fresh water.
- Disadvantages
- Large wastage of gametes.
- Large numbers of gametes produced.d
- Less chance of gamete fusion.
- 1. Haploid sperm cell fuses with the haploid egg cell.
- How flowering (Angiosperm) plants colonise the land.
- Development of a seed which contains the embryo, roots and shoots.
- Seed contain a foodstore.
- Enables it to survive for long periods of time.
- Large numbers of seeds are produced.
- Pollen can survive without water (except ferns and mosses).
- Relationship with animals and insects for pollination and seed dispersal.
- Seed Coat (Testa)
- Protects the embryo and prevents it from drying out.
- Water carrying xylem vessels.
- Asexual Reproduction
- Advantage
- Allows rapid increase number/out competes sexual reproduction.
- Asexual Reproduction
- Produces offspring genetically identical to the parent.
- Offspring are clones.
- One Parent
- Mitosis
- Disadvantage
- If conditions change individuals in the species may die because they are unable to adapt.
- No genetic variation
- e.g. Amoeba
- Produces offspring genetically identical to the parent.
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