Seed Dispersal

Key Notes :

Seed Dispersal | KS3 Biology Revision

1. Definition of Seed Dispersal:

  • Seed dispersal is the process by which seeds are spread from the parent plant to different locations, where they can grow into new plants.
  • This helps plants avoid overcrowding, find more resources (like sunlight, water, and nutrients), and prevent the spread of diseases.

2. Importance of Seed Dispersal:

  • Reduces competition: Seeds move away from the parent plant, which reduces competition for resources.
  • Increases plant diversity: It allows plants to colonize new areas and maintain genetic diversity.
  • Survival of species: By dispersing seeds, plants increase the likelihood of their survival in different environments.

3. Methods of Seed Dispersal:

There are several ways in which seeds can be dispersed. The primary methods are:

  • Wind Dispersal:
    • Seeds are lightweight and can be carried by the wind over long distances.
    • Example: Dandelion seeds, maple seeds (helicopters).
  • Water Dispersal:
    • Seeds float on water and are carried away to new areas, especially near rivers, lakes, and oceans.
    • Example: Coconut seeds can float in water for long distances.
  • Animal Dispersal:
    • Animals either eat the fruit and excrete the seeds elsewhere or seeds stick to their fur and are carried to new locations.
    • Example: Berries eaten by birds, burdock seeds sticking to animal fur (like thistles).
  • Explosive Dispersal:
    • Some plants have seed pods that explode when they mature, throwing seeds outward with force.
    • Example: Pea plants, poppy plants.
  • Human Dispersal:
    • Humans play a role in seed dispersal by transporting seeds intentionally or accidentally (through agriculture, gardening, or travel).
    • Example: Fruit crops transported to different regions.

4. Adaptations for Seed Dispersal:

  • Winged seeds: Some seeds are designed to glide in the air (e.g., maple seeds).
  • Spiny or hooked seeds: These seeds are designed to attach to animals (e.g., burrs).
  • Fleshy fruits: Fruits with edible flesh attract animals, which eat them and disperse the seeds.
  • Light seeds: Some seeds are small and light, allowing them to be carried by wind or water.

5. Examples of Plants and Their Dispersal Methods:

  • Coconut: Dispersed by water, as coconuts can float across oceans.
  • Dandelion: Dispersed by wind, with light, feathery seeds.
  • Burdock: Dispersed by animals, as the seeds stick to their fur.
  • Peas: Explosive dispersal, where seed pods burst open when ripe.

6. Impact of Seed Dispersal:

  • Helps plants colonize new areas and spread across different regions.
  • Some plants rely on specific dispersal methods (like animals or wind), which can affect their distribution.
  • Seed dispersal can lead to the growth of new ecosystems, promoting biodiversity.

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