Ecology is all about how living things interact with each...
GCSE Ecology Revision Questions









Ecosystems, Competition and Adaptations
Every ecosystem is like a massive community where living things interact with their surroundings. Abiotic factors are the non-living parts of the environment - things like temperature, light intensity, and soil pH that affect where organisms can survive.
Biotic factors are all the living components that influence each other. These include food availability, new predators showing up, or diseases spreading through populations. Plants compete for light, space, water, and minerals from the soil, whilst animals fight over territory, food, water, and mates.
Interdependence means species rely on each other for survival - remove one species and it creates a domino effect throughout the entire community. Organisms have developed three types of adaptations: structural (body features like shape or colour), behavioural (like migration patterns), and functional (internal processes like metabolism).
Key Point: Environmental changes from seasonal shifts, geographical factors, or human activity can dramatically affect where species can live and thrive.

Studying Organisms and Food Chains
Extremophiles are tough microorganisms that live in extreme conditions where most life couldn't survive. Scientists study organism distribution using quadrats (square frames) and transects (straight lines across habitats) to count and compare populations in different areas.
Producers like green plants and algae kick off every food chain by making glucose through photosynthesis. This glucose becomes their biomass - the building blocks of life. Food chains follow a simple pattern: Producers → Primary Consumers (herbivores) → Secondary Consumers (carnivores) → Tertiary Consumers.
Predator-prey relationships create natural cycles where populations rise and fall together. When there's lots of prey, predator numbers increase. As predators eat more prey, prey numbers drop, which then causes predator numbers to fall too.
Remember: Energy transfers between organisms when they eat each other, but materials like carbon and nitrogen get recycled through the environment to be used again and again.

Cycles and Decomposition
The carbon cycle keeps carbon moving between the atmosphere, living things, and the environment. Plants remove CO₂ during photosynthesis, animals release it through respiration, and decomposers break down dead organisms to return carbon to the soil and air.
The water cycle uses the sun's energy to evaporate water from seas, which condenses into clouds and falls as rain to provide fresh water for all life. It's a continuous loop that's been running for billions of years.
Decomposition breaks down dead organisms and waste, creating compost that acts as natural fertiliser. The rate of decay depends on temperature (warmer speeds it up), oxygen availability, water levels, and the number of decomposer organisms present.
Practical Tip: In the decay rate experiment, you'll use lipase enzyme to speed up the decomposition process and measure how temperature affects the rate using the formula: rate = 1000/time.

Environmental Changes and Biodiversity
Biodiversity - the variety of species in an ecosystem - keeps environments stable because different species depend on each other. However, human population growth is reducing biodiversity as we demand more resources and energy, taking materials from the environment faster than they can be replaced.
Human waste pollutes water, land, and air in different ways. Landfills leak toxic chemicals into waterways, pesticides damage soil and organisms, and industrial emissions create acid rain. Deforestation in tropical areas worsens climate change by reducing photosynthesis and releasing stored carbon when trees are burned.
Global warming results from increasing greenhouse gases like CO₂ and methane. This causes rising sea levels, flooding, habitat loss, and forces species to change their migration patterns or face extinction.
Action Point: Scientists create conservation programmes including breeding endangered species, protecting rare habitats, and encouraging recycling to minimise ecosystem damage - though these efforts face challenges from cost and economic pressures.

Trophic Levels and Energy Transfer
Trophic levels represent the different stages of food chains, with four main levels. Level one contains producers (plants and algae), level two has primary consumers (herbivores), level three includes secondary consumers (carnivores), and level four features tertiary consumers - the apex predators at the top.
Pyramids of biomass show how much living material exists at each trophic level. Producers only capture about 1% of available light energy, and approximately 10% of biomass transfers to each higher level. The rest gets lost through incomplete eating, excretion, and respiration.
Decomposers like bacteria and fungi break down dead organisms by secreting enzymes that turn complex materials into simple molecules they can absorb. This recycling process is essential for returning nutrients to the ecosystem.
Calculation Key: Biomass transfer efficiency = (biomass transferred to next level ÷ biomass at previous level) × 100

Food Security and Production
Food security means having enough food to feed everyone, but it's threatened by growing populations, changing diets in developed countries, new pests and diseases, environmental changes, and conflicts over resources.
Overfishing has caused fish stock declines, but solutions include fishing quotas (limits on catches) and using bigger mesh nets so young fish can escape to reach breeding age. Food production efficiency improves by restricting animal movement, controlling temperatures, and feeding high-protein diets - though these intensive methods raise disease spread and animal welfare concerns.
Biotechnology uses living organisms to create useful products. Mycoprotein from Fusarium fungus provides high-protein meat substitutes for vegetarians. Human insulin production involves inserting human genes into bacteria using restriction enzymes and plasmids.
Ethics Check: Genetic modification can create pest-resistant crops and improve nutrition , but critics argue we should tackle poverty and soil quality issues first rather than just modifying crops.


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GCSE Ecology Revision Questions
Ecology is all about how living things interact with each other and their environment - think of it as nature's big web of connections. You'll discover how organisms compete, adapt, and depend on each other, plus learn about the impact...

Ecosystems, Competition and Adaptations
Every ecosystem is like a massive community where living things interact with their surroundings. Abiotic factors are the non-living parts of the environment - things like temperature, light intensity, and soil pH that affect where organisms can survive.
Biotic factors are all the living components that influence each other. These include food availability, new predators showing up, or diseases spreading through populations. Plants compete for light, space, water, and minerals from the soil, whilst animals fight over territory, food, water, and mates.
Interdependence means species rely on each other for survival - remove one species and it creates a domino effect throughout the entire community. Organisms have developed three types of adaptations: structural (body features like shape or colour), behavioural (like migration patterns), and functional (internal processes like metabolism).
Key Point: Environmental changes from seasonal shifts, geographical factors, or human activity can dramatically affect where species can live and thrive.

Studying Organisms and Food Chains
Extremophiles are tough microorganisms that live in extreme conditions where most life couldn't survive. Scientists study organism distribution using quadrats (square frames) and transects (straight lines across habitats) to count and compare populations in different areas.
Producers like green plants and algae kick off every food chain by making glucose through photosynthesis. This glucose becomes their biomass - the building blocks of life. Food chains follow a simple pattern: Producers → Primary Consumers (herbivores) → Secondary Consumers (carnivores) → Tertiary Consumers.
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Action Point: Scientists create conservation programmes including breeding endangered species, protecting rare habitats, and encouraging recycling to minimise ecosystem damage - though these efforts face challenges from cost and economic pressures.

Trophic Levels and Energy Transfer
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Decomposers like bacteria and fungi break down dead organisms by secreting enzymes that turn complex materials into simple molecules they can absorb. This recycling process is essential for returning nutrients to the ecosystem.
Calculation Key: Biomass transfer efficiency = (biomass transferred to next level ÷ biomass at previous level) × 100

Food Security and Production
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