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World of Plants

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Germination is the growth of a plant embryo into a new plant ... Large, bright and nice scent. Small, dull, no scent. petals. Insect pollinated flower ... – PowerPoint PPT presentation

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Title: World of Plants


1
World of Plants
  • Revision

2
Uses of plants
RAW MATERIALS
MEDICINES
Foxglove
Periwinkle
Rubber
Pine
Cotton
Seaweed
Poppy
Cabbage
Wheat
Sunflower
3
Structure of a seed
4
Germination
  • Germination is the growth of a plant embryo into
    a new plant
  • For germination seeds need the following
  • Water
  • Oxygen
  • Suitable temperature
  • Remember seeds do NOT need LIGHT (think about
    where seeds are usually planted)

5
Structure of a flower
Petals
Nectary
Sepals
6
The male and female parts of a flower
7
Pollination
Pollen is produced in the anthers
8
Pollination 2
9
Animal and wind pollination
  • Most flowers have the same basic structure, but
    many flowers are ADAPTED to increase their
    chances of pollination (either by wind or by
    animals).

10
Growth of a pollen tube
  • Once pollen land on the stigma it uses sugar on
    the stigma for energy to form a pollen tube
  • The male nucleus of the pollen grain travels down
    the pollen tube to the ovary where it meets and
    fuses with the female nucleus in the ovule
  • Following fertilisation, the ovule becomes a SEED
    and the ovary becomes the FRUIT

11
Seed Dispersal
  • If seeds are well dispersed the chance of
    survival is greater because competition is
    reduced
  • There are 3 seed dispersal mechanisms
  • Wind e.g. sycamore seed. These seeds are very
    light so they can be carried easily
  • Animal internal e.g. cherry. These seeds are
    bright coloured and juicy to entice an animal
  • Animal external e.g. burdock. These seeds can
    have hooks which attach to an animals fur

12
Asexual reproduction
  • Plants can also reproduce asexually
  • This means that sex cells and fertilisation are
    not involved
  • Plants that are produced in this way are CLONES
    which means they are genetically identical to
    each other
  • Asexual reproduction can occur NATURALLY or
    ARTIFIALLY

13
Natural Methods
  • Runners these are side shoots that grow out
    from the parent plant. At the end of the runner a
    new plantlet will grow which will form roots when
    it comes into contact with the ground
  • Tubers this is a swollen region of a stem or
    root which is a food storage organ

14
Artificial Methods
  • Humans can reproduce plants artificially in 2
    ways
  • Cuttings a piece of stem or leaf is cut and
    placed in compost where it will form roots
  • Grafting a bud or shoot of a valuable plant is
    taken and joined to a plant that already has a
    root system

15
Which is best sexual or asexual reproduction?
16
Making Food Transport systems
  • Plants need both water and dissolved food in all
    parts of the plant
  • Therefore, they need transport systems to move
    these substances around the plant
  • XYLEM and PHLOEM are the 2 main transport systems

17
Features of xylem and phloem
18
Xylem and Phloem
  • Together, xylem and phloem form the VASCULAR
    BUNDLES

19
Leaf Structure
(transparent to let light through)
Palisade mesophyll cells (contains many
chloroplasts. These cells are where most
photosynthesis occurs)
Spongy mesophyll cells (have air spaces between
them to allow easy gas exchange
20
Stomata
  • Stomata are tiny pores on the surface of leaves
    that allow gases in and out
  • Carbon dioxide enters a leaf from the air
  • Oxygen is produced during photosynthesis and this
    passes out of the leaf through stomata
  • Stomata are open during the day and closed at
    night to prevent water being lost
  • http//www.bbc.co.uk/schools/gcsebitesize/biology/
    greenplantsasorganisms/1watertransportrev3.shtml

21
Photosynthesis
  • Green plants use LIGHT to combine CO2 and H2O
    together to make GLUCOSE and OXYGEN
  • CHLOROPHYLL is the green chemical found in plants
    and it is essential for photosynthesis

22
The fate of food
  • The food that the plants make is a carbohydrate
  • The simplest carbohydrate is glucose which can
    have different fates
  • It can be used straight away as an energy source
  • It can be converted to starch which can be stored
    until it is needed

23
Limiting Factors
  • A limiting factor is something which slows down
    or stops a process from happening
  • Photosynthesis can be limited if certain things
    are in short supply
  • The most common limiting factors in
    photosynthesis are low LIGHT, lack of CO2 or low
    temperatures
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