AQA GCSE FOUNDATION Biology: Ecosystems and Interdependence

AQA GCSE Foundation Biology: Ecosystems and Interdependence - Organism Interactions

This tutorial will explore the fascinating world of interactions between organisms within ecosystems.

1. Key Concepts:

• Ecosystem: A community of interacting organisms and their physical environment.
• Interdependence: The mutual reliance of organisms within an ecosystem.
• Food Web: A complex network of interconnected food chains showing the flow of energy and nutrients.
• Trophic Levels: The different levels in a food web, based on how organisms obtain energy.

2. Types of Organism Interactions:

Organisms within an ecosystem interact in a variety of ways, often involving:

• Predator-Prey Relationships:

  • Predator: An animal that hunts and kills other animals for food.
  • Prey: The animal that is hunted and killed.
  • Example: A fox (predator) hunting a rabbit (prey).

• Competition:

  • Occurs when organisms require the same limited resources (food, water, space, mates).
  • Intraspecific: Competition between members of the same species.
  • Interspecific: Competition between members of different species.
  • Example: Two oak trees competing for sunlight and nutrients.

• Parasitism:

  • A relationship where one organism (parasite) benefits at the expense of another (host).
  • Example: A tapeworm living in the intestines of a human, absorbing nutrients from the host.

• Mutualism:

  • A relationship where both organisms benefit.
  • Example: Bees pollinating flowers, getting nectar while aiding in the flower's reproduction.

• Commensalism:

  • A relationship where one organism benefits, while the other is neither harmed nor helped.
  • Example: Barnacles living on whales, obtaining food and transport without harming the whale.

3. The Importance of Interdependence:

Interdependence is crucial for the stability and resilience of ecosystems:

• Population Control: Predator-prey relationships help control populations of both species.
• Resource Utilization: Competition helps to optimize resource use and prevent overgrazing.
• Nutrient Cycling: Decomposition by bacteria and fungi returns nutrients to the ecosystem.
• Biodiversity: Diverse interactions contribute to the overall richness and complexity of an ecosystem.

4. Impact of Changes on Interactions:

Changes in an ecosystem can have a significant impact on organism interactions:

• Habitat Loss: Reduces resources and creates competition, potentially leading to extinction.
• Pollution: Can harm organisms and disrupt food webs.
• Climate Change: Alters temperature, rainfall, and habitats, affecting species distributions and interactions.

5. Key Examples:

• The African Savanna: Lion (predator) and zebra (prey), competition between different herbivores for grazing, mutualistic relationship between acacia trees and ants.
• The Tropical Rainforest: Parasitic vines growing on trees, mutualistic relationship between flowers and pollinators.
• The Coral Reef: Competition between corals for space, mutualistic relationship between corals and algae.

6. Conclusion:

Understanding organism interactions is essential for comprehending the functioning of ecosystems. By studying how different species rely on each other, we can gain insights into the delicate balance of nature and the importance of conservation efforts.