SCIENCE TERM 3

What is an ecosystem?

A community of living organisms interacting with each other and with their non-living environment.

What are the two main components of an ecosystem?

Biotic factors and abiotic factors.

What are biotic factors?

The living parts of an ecosystem, such as plants, animals, fungi and bacteria.

What are abiotic factors?

The non-living parts of an ecosystem, such as sunlight, temperature, water, soil and wind.

How can you remember biotic?

BIO = life, so biotic means living.

Give 5 examples of abiotic factors.

Temperature, sunlight, water, soil and wind.

How do abiotic factors affect organisms?

They can affect where organisms live, how well they grow, their survival and their population size.

Give an example of an interaction between biotic and abiotic factors.

Plants need sunlight and water to grow. In turn, plants can provide shade and shelter for animals.

Where does most energy in an ecosystem originally come from?

The Sun.

What is a producer?

An organism that makes its own food, usually through photosynthesis.

Give 3 examples of producers.

Grass, trees and algae.

What is a consumer?

An organism that gets energy by eating other organisms.

What is a primary consumer?

An organism that eats producers, usually a herbivore.

What is a secondary consumer?

An organism that eats primary consumers.

What is a tertiary consumer?

An organism that eats secondary consumers.

What is a decomposer?

An organism that breaks down dead organisms and waste.

Give 2 examples of decomposers.

Fungi and bacteria.

What is the basic energy pathway in an ecosystem?

Sun → producers → consumers → decomposers.

What is a food chain?

A sequence showing one pathway of energy transfer between organisms.

What do arrows in a food chain show?

The direction that energy is transferred.

What is a food web?

A network of connected food chains showing multiple pathways of energy transfer.

What is the difference between a food chain and a food web?

A food chain shows one pathway, while a food web shows many connected pathways.

Identify the trophic levels: Grass → Grasshopper → Frog → Snake.

Grass = producer, grasshopper = primary consumer, frog = secondary consumer, snake = tertiary consumer.

What is a trophic level?

An organism's position in a food chain or food web.

What is always at the first trophic level?

Producers.

What is an energy pyramid?

A diagram showing the amount of available energy at each trophic level.

Which trophic level has the most energy?

Producers at the bottom.

What happens to energy as you move up an energy pyramid?

The amount of available energy decreases.

Why does energy decrease at higher trophic levels?

Organisms use energy for life processes such as movement, growth and respiration, and some energy is released as heat.

What is the approximate 10% rule?

About 10% of the energy at one trophic level is transferred to the next trophic level.

Why are there usually fewer top predators than producers?

There is less available energy at higher trophic levels, so ecosystems can support fewer organisms.

What happens to energy that isn't transferred to the next trophic level?

Much of it is used by the organism or released into the environment as heat.

Does energy or matter cycle through ecosystems?

Matter cycles, while energy flows.

Give 4 examples of matter that cycles through ecosystems.

Water, carbon, oxygen and nitrogen.

What is the water cycle?

The continuous movement of water through the atmosphere, land, oceans and living organisms.

What is evaporation?

When liquid water changes into water vapour due to heating.

What is condensation?

When water vapour cools and changes into liquid water droplets.

What is precipitation?

Water falling from clouds as rain, snow or hail.

What is photosynthesis's role in the carbon cycle?

Plants remove carbon dioxide from the atmosphere and use the carbon to make glucose.

How is carbon returned to the environment?

Through respiration, decomposition and other processes.

What is the key difference between energy and matter?

Energy flows through ecosystems and is eventually released as heat, while matter is recycled.

What is a population?

All organisms of the same species living in a particular area.

What can cause a population to increase?

More food, water and space, more births, fewer predators and fewer diseases.

What can cause a population to decrease?

Less food or water, disease, predation, competition, habitat loss and extreme weather.

What is competition?

When organisms compete for limited resources such as food, water, space or mates.

What is predation?

When one organism hunts and eats another organism.

What is carrying capacity?

The largest population an environment can sustainably support.

What can happen if a population becomes larger than the carrying capacity?

Resources become limited, competition increases and the population may decrease.

What is an introduced species?

A species that has been brought into an area where it does not naturally occur.

What is an invasive species?

An introduced species that spreads and causes harm to the environment, economy or native species.

How can introduced species affect native organisms?

They may compete for resources, prey on native species, spread disease or damage habitats.

Give an example of an introduced species in Australia.

European rabbits.

How can rabbits affect Australian ecosystems?

They eat vegetation, compete with native herbivores and can contribute to soil erosion.

Explain how an introduced species can cause a population to decrease.

The introduced species may compete for food or habitat, leaving fewer resources for native species and causing their population to decrease.

What does endangered mean?

A species that is at high risk of becoming extinct.

What does extinct mean?

A species has no living individuals remaining.

What is habitat loss?

When an organism's natural habitat is destroyed, reduced or changed.

What are 6 causes of species becoming endangered?

Habitat loss, climate change, pollution, introduced species, overhunting/overfishing and disease.

How can climate change cause species to become endangered?

Changes in temperature, rainfall and extreme weather can make habitats unsuitable for organisms.

How can pollution cause species to become endangered?

Pollution can contaminate food, water and habitats, harming organisms and reducing their populations.

How can habitat destruction cause extinction?

Organisms lose food, shelter and breeding areas, causing populations to decrease and potentially reach zero.

What is biodiversity?

The variety of different living organisms in an area.

Why is biodiversity important?

It helps ecosystems remain healthy and stable because different organisms perform different roles.

What is an independent variable?

The variable that you deliberately change.

What is a dependent variable?

The variable that you measure or observe.

What are controlled variables?

Variables that are kept the same to make an experiment fair.

Easy way to remember independent and dependent variables?

Independent = I change it. Dependent = I measure it.

What is a hypothesis?

A testable prediction about what you think will happen.

What is a fair test?

An investigation where the independent variable is changed while other important variables are controlled.

How can you improve reliability?

Repeat the experiment several times and calculate an average.

What is an anomaly?

A result that does not fit the general pattern of the data.

What is a trend?

A general pattern or relationship shown by data.

How should you use data in a scientific answer?

Use specific numbers or observations from the table or graph as evidence.

What words can you use to explain cause and effect?

Because, therefore, as a result, this causes, this leads to, consequently and due to.