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PLANT REPRODUCTION - Coggle Diagram
PLANT REPRODUCTION
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GROWTH CURVE
Growth can be measure by length, height, volume, fresh mass, dry mass of organism
SIGMOID CURVE:
- Rate of growth of plant is not always the same during its life span. Sometimes it will slow and also can be rapid.
- If we plot it over time, a S-shape curve is obtained.
- It is called sigmoid growth curve.
The curves has 3 phases:
- Lag phase: Initial phase of growth (slow rate)
- Log phase: Shows rapid growth (maximum growth)
- Stationary phase: Rate of growth starts decreasing and stop
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FORMATION OF POLLEN
- Pollen grains are formed in the anther.
- One anther has 4 pollen sacs. Each pollen sacs contains hundred of cells( pollen mother cells )
- Each pollen mother cells undergo meiosis and produce 4 haploid microspores.
- Microspores develop into pollen grains.
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Flowers is the reproductive organ of a flowering plant. Flowers contains 4 basic part:
- Stamens&carpels: male n female reproductive organs
- Sepals&petals: non-reproductive organs
FORMATION OF EMBRYO SAC IN OVULE
- Ovule develop from ovarian tissue and has diploid embryo sac mother cell.
- Embryo sac mother cell undergo meiosis to form 4 megaspores. 3/4 degenerate leaving 1.
- Nucleus of megaspore undergo mitosis three times to form 8 haploid nuclei.
- 3/8 become antipodal cell migrate to one end // 2/8 are called polar nuclei at the centre // 3/8 move to the nearest opening of ovule and develop into 1 egg cell and 2 synergid cell.
- Structure known as embryo sac.
FORMATION OF POLLEN TUBE, ZYGOTE & TRIPLOID NUCLEUS
- Pollination: mature pollen grain are transferred to stigma of flower from anther
- Pollen grain initiates fertilisation. Pollen grain germinate to form tube (pollen tube).
- Pollen tube grows down nucleus and give space for 2 male nuclei follow the tube down.
- Double fertilisation occurs as they reach ovary. 1 male nucleus fuses with egg nucleus. The other male fuses with 2 polar nuclei