CH12 REPRODUCTION IN FLOWERING PLANTS

Type of reproduction

1. Sexual

Asexual reproduction

Binary fission

Bacteria: 1 --> 2

Vegetative propagation

  1. In winter the aerial part of the plant dies. The underground storage organ is dormant
  2. Favourable conditions: aerial shoots dev from buds. Storage organ provides food for growth
  3. Advantitious roots formed. abs water and minerals from soil. Green leaves dev
  4. Shoots dev into new plants. Storage organ dries as food used
  5. Plant carries photosynthesis to make food stored in new storage organs

Storage organs

1. Stem tuber

Artificial vegetative propagation

cutting leaf put in water
When roots dev
cutting put in soil

Sexual reproduction

Sepals: form calyx protects inner parts of flower in budding
Petals: make corolla, Brightly coloured/ scented, nectar guides lead insects to nectaries at base

Male organs (Stamens)

Females organs (Carpels)

Pollination

Transfer of pollen grains from anthers to stigmas

  1. Self-/cross-pollination
  1. Insect/wind pollination
Insect Wind
Petals Large and brightly coloured, often hae nectar guides Reduced, green and dull-coloured
Scent Present Absent
Nectaries Present Absent
Anthers Located inside flower, firmly attached to filaments Hang outside flower, loosely attached to filaments
Pollen grains larger, heavier, rough spiky sticky, less Smaller, lighter, smooth, dry, more
Stigmas Inside flower, sticky surface Outsie flower, long and feathery

Process

  1. Pollen grains land of stigma
  2. Suagry solution of stigma stimulates germination of pollen grain. Pollen tube develops from pollen grain
  3. Pollen tube grows down the style and into ovary by secreting enzymes to digest style tissue, carrying male gamete to ovule.
  4. Pollen tube grows through micropyle. Tip bursts to release male gamete to ovule
  5. Male and female gamete fuses to form zygote

Before and after

Floral part After fertilization
Ovary Fruit
Ovary wall Fruit wall
Ovule Seed
Ovum Embryo
Integuments Seed coat
Sepals,petal, stamen Wither and fall off
Remains of stimga and style Scar

Fruit: protect seeds and help dispersal

Seed dispersal

Methods:

  1. Wind dispersal
  2. Water currents
  3. faeces of animals
  4. hairs of animals
    Significances:
  5. Reduce overcrowding and competition for resouces among daughter and parent plants
  6. Allows species to colonise new areas
  7. Escape from pests and diseases associated with parent plants

Showdown

Asexual Sexual
Desirable characteriscs retained in offspring Desirable characteriscs not retained
No external agents required External agents required
Fast rate Slow rate
No genetic variations in offspring, species less adapted to environmental changes Genetic variations in offspring help species adapt to environmental changes
Overcrowding and competition of resources among offspring and parents Overcrowding and competition is reduced
More likely to tramsit diseases to offspring Less likely to transmit diseases to offspring