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Ecology and Environmental Science Overview

Mar 23, 2025

Ecology - AQA Biology GCSE

Adaptations, Interdependence, and Competition (7.1)

Communities (7.1.1)

  • Individual: Part of a species, lives in a habitat within a population.
  • Community: Different populations interacting in the same habitat.
  • Ecosystem: Interaction of a community with abiotic parts.
  • Competition: Organisms require the same resources.
    • Plants: Compete for light, space, water, mineral ions.
    • Animals: Compete for space, food, water, mating partners.
  • Interdependence: Organisms depend on each other for services (food, shelter, reproduction).
  • Stable Community: Biotic and abiotic factors in balance, resulting in constant population sizes.

Abiotic Factors (7.1.2)

  • Light Intensity: Affects photosynthesis rate, plant growth.
  • Temperature: Influences photosynthesis rate.
  • Moisture Levels: Essential for survival of plants/animals.
  • Soil pH & Mineral Content: Impacts decay rate and nutrient uptake.
  • Wind Intensity & Direction: Affects transpiration and photosynthesis.
  • Carbon Dioxide Levels: Influences photosynthesis and organism distribution.
  • Oxygen Levels for Aquatic Animals: Affect survival; fish require high oxygen.

Biotic Factors (7.1.3)

  • Food Availability: More food supports population growth.
  • New Predators: Can lead to population decline.
  • New Pathogens: Lack of resistance can wipe out populations.
  • Competition: Better adapted species outcompete others.

Adaptations (7.1.4)

  • Structural: Physical characteristics like sharp teeth, camouflage, fat for insulation.
  • Behavioural: Behaviors like playing dead, basking, mating rituals.
  • Functional: Processes like reproduction and metabolism adaptations.
  • Extremophiles: Thrive in extreme conditions (temperature, pressure, salinity).

Organisation of an Ecosystem (7.2)

Levels of Organisation (7.2.1)

  • Food Chains: Show feeding relationships, starting with producers.
  • Producers: Photosynthetic organisms, creating glucose.
  • Consumers: Primary (herbivores), Secondary (carnivores), Tertiary (apex predators).
  • Population Cycles: Predators and prey cycles affect each other's populations.

How Materials are Cycled (7.2.2)

  • Carbon Cycle: Photosynthesis, respiration, combustion cycle carbon.
  • Water Cycle: Evaporation, condensation, precipitation, and runoffs.

Decomposition (7.2.3 - Biology Only)

  • Factors Affecting Rate: Temperature, water, and oxygen availability.
  • Compost: Produced as organic material decays.
  • Methane Gas: Produced anaerobically, used as fuel.
  • Biogas Generators: Used to produce methane for energy.

Impact of Environmental Change (7.2.4 - Biology Only)

  • Temperature: Affects species distribution due to climate change.
  • Water Availability: Leads to migration.
  • Atmospheric Composition: Pollutants like sulfur dioxide affect species like lichen.

Biodiversity and Human Impact (7.3)

Biodiversity (7.3.1)

  • Defined as variety of species on Earth or within an ecosystem.
  • High biodiversity ensures ecosystem stability.
  • Human activities negatively affect biodiversity.

Waste Management (7.3.2)

  • Human waste and land use reduce habitats and increase pollution.

Land Use (4.7.3.3)

  • Activities like building and farming reduce habitats.
  • Peat Bogs: Destroyed for agriculture and fuel use.

Deforestation (7.3.4)

  • Occurs for agriculture and biofuel production.
  • Leads to CO2 increase and biodiversity loss.

Global Warming (7.3.5)

  • Temperature rise from greenhouse gases affects habitats and species distribution.

Maintaining Biodiversity (7.3.6)

  • Breeding Programs: Save endangered species.
  • Protection & Reintroduction: Habitat conservation efforts.
  • Reducing Deforestation & Recycling: Mitigate human impact.

Trophic Levels in an Ecosystem (7.4)

Trophic Levels (7.4.1)

  • Producers: Level 1, make food via photosynthesis.
  • Primary Consumers: Level 2, herbivores.
  • Secondary Consumers: Level 3, carnivores.
  • Tertiary Consumers: Level 4, apex predators.
  • Decomposers: Break down dead material.

Pyramids of Biomass (7.4.2)

  • Show relative biomass at each trophic level.

Transfer of Biomass (7.4.3)

  • Efficiency: Only ~10% biomass transfer between levels.

Food Production (7.5 - Biology Only)

Factors Affecting Food Security (7.5.1)

  • Birth rates, diets, pests, climate change, and conflicts affect food availability.

Farming Techniques (7.5.2)

  • Efficient Farming: Reduces energy waste, often ethical concerns arise.

Sustainable Fisheries (7.5.3)

  • Overfishing reduced by quotas and net size regulations.

Role of Biotechnology (7.5.4)

  • Mycoprotein: Vegetarian protein source.
  • Genetically Modified Crops: Pest/weather resistant and nutritious.
  • Insulin Production: Biotech helps treat diabetes.