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Title:

Plant reproduction

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Title: Plant Life Cycle Author: kellyl5 Last modified by: GordoR3 Created Date: 5/14/2009 7:20:17 AM Document presentation format: On-screen Show Company – PowerPoint PPT presentation

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Title: Plant reproduction


1
Plant reproduction
  • Sexual reproduction

2
Learning Intentions
  • I can describe methods of sexual reproduction in
    plants
  • I can describe the process of pollination,
    fertilisation , seed formation and dispersal

3
Success Criteria
  • Success Criteria
  • I can state plants use flowers as a method of
    sexual reproduction
  • I can put the stages of a plants life cycle in
    order
  • I can define pollination and fertilisation
  • I can describe how pollination and fertilisation
    occurs in plants
  • I can explain how seeds are formed
  • I can describe methods of seed dispersal
  • I can explain the advantages of seed dispersal
  • I am able to label diagrams correctly

4
Plant Life Cycle
  • A plants life cycle shows all the stages in a
    flowers life
  • From seed to flower
  • And back to seeds
  • This is plant reproduction
  • It allows plants to reproduce so new flowers will
    form again and again

5
Tomato plant life cycle
6
(No Transcript)
7
Parts of a flower
  • Petals bright to attract insects
  • Stamen contains the anther which splits down the
    middle to release the pollen

8
Stigma
  • The stigma is the region to which pollen grains
    become attached

9
  • Nectary makes sugary nectar which insects eat
  • Sepals - protects unopened flower
  • Ovary female part of the flower that contains
    the ovules

10
Pollination
11
  • The pistil is part of the stigma.
  • Pollination is the transfer of pollen from the
    anther to the stigma

12
Insect pollination
e.g. Passion flower
13
Wind Pollination
e.g. Sedge
14
Methods of Pollination
Insect pollination Wind pollination
Have a scent No scent
Sticky, spiky pollen Large amounts of light pollen
Sticky stigma inside flower Feathery stigmas hang outside the flower
Stamens surrounded by petals Large stamens hang outside flower
Produce nectar Dont produce nectar
Petals large bright Petals small dull
15
Fertilisation
  • Once the pollen grain lands on the stigma, it
    grows a pollen tube down to the ovule.
  • Fertilisation is when the nucleus of the pollen
    grain fuses with the nucleus of the ovule
  • The fertilised ovule develops into a seed
  • The ovary wall develops into the fruit.

16
Seed dispersal
  • Following pollination and fertilisation seed
    formation and dispersal takes place
  • Seed Dispersal this is where seeds are
    scattered away from the parent
  • Seeds are scattered to avoid competition for
    water, light and nutrients

17
Animal (external)
  • Seeds can be dispersed by animals.
  • The seed has hooks which catch onto animals fur
    and are transported by the animal until they fall
    off and hopefully germinate elsewhere.
  • E.g. Burdock

18
Animal (internal)
  • Seeds can also be eaten by animals along with the
    fruit.
  • The seeds pass through the animal and are
    deposited in the droppings elsewhere
  • E.g. bramble

19
Wind Dispersal
  • Plants can also use the wind to scatter their
    seeds and they use different mechanisms to
    achieve this.
  • E.g. the poppy uses the pepper pot method

20
Wind Dispersal
  • Ragwort, dandelions, cotton, etc. use the
    parachute method.
  • Each seed has a number of small feather-like
    structures to help it float in the wind.

21
Wind Dispersal
  • Some seeds have wings to help them fly in the
    wind.
  • E.g. sycamore, ash, etc..

22
Explosive
  • Some plants such as peas and gorse use pods which
    explode to fire the seeds away from the parent.
  • As a pod dries, tensions are set up in the wall
    of the pod eventually causing it to split along
    two lines of weakness.

23
Advantages of seed dispersal
  • It reduces competition for resources eg. light,
    water and mineral nutrients
  • It reduces the spread of disease
  • It allow plants to grow in a wider area so more
    likely to survive in event of a flood or fire.

24
Seed germination
  • With water, oxygen and the right temperature the
    seed swells and begins to make a new plant
  • Germination occurs
  • Stems grow up towards the light, leaves unfold to
    take more sunlight and roots anchor the plant
  • Growth
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