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.