Ecosystems, Adaptations & Human Impacts – Revision Cards

These question-and-answer flashcards cover key topics from the lecture notes: ecosystem basics, adaptations, species interactions, trophic dynamics, photosynthesis, microorganisms, environmental disturbances, and agricultural biotechnology.

What is an ecosystem?

A system formed by organisms interacting with each other and with their non-living surroundings in a balanced way.

How does an environment differ from a habitat?

The environment is the combination of all external conditions affecting an organism, while a habitat is the specific place where that organism lives inside an ecosystem.

What are biotic factors?

The living components of an ecosystem, collectively called the community.

What are abiotic factors?

The non-living components of an ecosystem that make up the physical environment (e.g., temperature, light, soil, water).

List six basic resources a habitat must supply for an organism to survive and reproduce.

Food, water, shelter, living space, mating partners, and essential gases such as oxygen.

Define adaptation.

A hereditary characteristic that increases an organism’s chance of survival and reproduction in its environment.

What is a structural adaptation?

A physical feature of an organism that enhances survival, e.g., the streamlined body of a dolphin.

What is a behavioural adaptation?

An action or pattern of activity that helps an organism survive, e.g., birds migrating to avoid cold winters.

What is a physiological adaptation?

An internal body process that aids survival, such as a camel storing fat in its hump or snakes producing venom.

Explain how adaptations arise in a population.

Random mutations during reproduction create differences; if a mutation improves fitness, natural selection favours and passes it on to future generations.

Why are adaptations vital in ecosystems?

They enable organisms to obtain resources, avoid predators, tolerate environmental conditions, and reproduce, maintaining population balance.

What does interdependent mean in ecology?

Organisms rely on each other for survival, growth, and reproduction through food chains, shelter, pollination, etc.

Define predator and prey.

A predator is an animal that hunts and eats other animals; the prey is the animal that is eaten.

What is commensalism?

A symbiotic relationship where one species benefits while the other is neither helped nor harmed (e.g., remora and shark).

What is mutualism?

A symbiotic relationship in which both species benefit, such as clownfish and sea anemone.

What is parasitism?

A symbiotic relationship where the parasite benefits and the host is harmed, possibly killed.

Describe the typical pattern in predator-prey population graphs.

Prey numbers rise, followed by a rise in predators; increased predation lowers prey, which later lowers predator numbers, and the cycle repeats.

What is a producer (autotroph)?

An organism, usually a green plant or algae, that makes its own food via photosynthesis.

Define consumer (heterotroph).

An organism that obtains energy by eating other organisms; includes herbivores, carnivores, and omnivores.

What is a decomposer?

An organism, such as bacteria or fungi, that breaks down dead matter and recycles nutrients back into the ecosystem.

Give the word equation for photosynthesis.

Carbon dioxide + Water → Glucose + Oxygen (in the presence of Sunlight & Chlorophyll).

State two ecosystem roles of photosynthesis.

1) Begins food chains by producing carbohydrates. 2) Removes CO₂ and releases O₂ to the atmosphere.

Give one beneficial effect of microbes in humans.

Intestinal microbes aid digestion, nutrient absorption, and out-compete harmful bacteria.

Give one harmful effect of microorganisms.

Pathogenic microbes cause diseases that reduce health, spoil food, or damage materials.

What percentage of energy is typically passed from one trophic level to the next?

Approximately 10%; about 90% is lost as heat or undigested matter.

Define trophic level.

The position an organism occupies in a food chain (e.g., producer, primary consumer, secondary consumer).

What is an apex predator?

The top predator in a food chain that has no natural predators.

Explain how energy flows in a food chain.

Energy originates from the sun, captured by producers, and moves one-way through consumers, with losses at each step as heat.

Differentiate a food web from a food chain.

A food chain is a single pathway of energy flow; a food web is a network of interconnected food chains in an ecosystem.

Define herbivore, carnivore, and omnivore.

Herbivore: eats plants only; Carnivore: eats animals only; Omnivore: eats both plants and animals.

What is biodiversity?

The variety of all living species within a region or ecosystem, including plants, animals, and microorganisms.

How can introduced species such as rabbits affect food webs?

They face fewer limiting factors, out-compete natives, alter habitats, and reduce biodiversity.

Identify three natural events that can disrupt Australian ecosystems.

Cyclone, drought, bushfire (and flood is a fourth example).

Describe one ecological impact of a cyclone.

Intense winds and storm surges destroy habitats, contaminate freshwater, and disrupt food chains.

How does drought affect food chains?

Reduced plant growth lowers food for herbivores, leading to cascading declines up the chain; aquatic habitats may dry out completely.

Why can bushfires sometimes aid certain plant species?

Fire-adapted plants like eucalyptus may germinate or resprout after burning, relying on fire to trigger regeneration.

Give one positive and one negative effect of floods on ecosystems.

Positive: deposit nutrients and refill wetlands; Negative: uproot vegetation, displace wildlife, and pollute water.

Define agriculture.

The science or practice of farming, including soil preparation, crop growing, animal rearing, and water management.

What is selective breeding?

The process of mating organisms with desirable traits to enhance those traits in future generations (e.g., seedless mangoes).

What is genetic cloning in agriculture?

Using tissue culture or other biotechnologies to create identical copies of a plant or animal possessing desirable characteristics.

Give one economic advantage of cloning high-demand crops.

Increases production efficiency, boosting farmer profits and lowering consumer prices.

Explain why decomposers are critical for soil fertility.

They break down organic waste into simple compounds, recycling minerals like nitrates and phosphates back into the soil.

What is the role of chlorophyll in photosynthesis?

It captures sunlight energy to convert carbon dioxide and water into glucose and oxygen.

How do microbes protect the skin?

By out-competing harmful bacteria and supporting the immune system against infections.

Why does energy flow in ecosystems form a pyramid shape?

Because energy decreases by ~90% at each trophic level, resulting in fewer organisms and less biomass at higher levels.