Ecosystem components
What is an ecosystem?
An ecosystem is a community of living organisms interacting with each other and with the non-living parts of their environment.
What is a food chain?
A food chain shows the transfer of energy from one organism to another through feeding relationships.
What does an energy pyramid show?
An energy pyramid shows the amount of energy available at each trophic level in an ecosystem.
What is predation?
Predation is an interaction where one organism, the predator, hunts and eats another organism, the prey.
What is an invasive species?
An invasive species is a non-native species that establishes itself in a new environment and causes harm to the ecosystem, economy or society.
What is the difference between a biotic and an abiotic factor?
Biotic = living Abiotic = non living
What is the difference between a food chain and a food web?
A food chain shows one pathway of energy flow, while a food web shows many interconnected food chains and feeding relationships within an ecosystem.
Which trophic level contains the most energy: producers, primary consumers or secondary consumers?
Producers
What is the difference between mutualism and parasitism?
Name one human activity that can negatively affect an ecosystem.
Examples include deforestation, pollution, overfishing, habitat destruction, introducing invasive species or burning fossil fuels.
Give an example of a biotic and abiotic factor
Biotic = plants, animals, decomposers
Abiotic = soil, sun, water, temperature
In the food chain grass → rabbit → fox, what would you predict would happen to the rabbit population if the fox population suddenly increased? Explain why.
The rabbit population would likely decrease because there would be more foxes hunting and eating rabbits.
Why is there less energy available at higher trophic levels?
Organisms use much of the energy they obtain for life processes such as movement, growth and maintaining their bodies. Therefore, only a smaller amount of energy is available to the next trophic level.
Two species of birds rely on the same limited supply of insects for food. What type of interaction are they experiencing? Explain.
Competition. The birds are competing because they require the same limited food resource.
Explain how an invasive species can compete with native species for resources.
An invasive species may use the same resources as native species, such as food, water, space or sunlight. This can reduce the resources available to native species and cause their populations to decline.
What is the role of a producer in an ecosystem?
Producers make their own food, usually through photosynthesis, and provide energy for other organisms in the ecosystem.
A food web contains grass, caterpillars, frogs, mice, snakes and hawks. If the frog population dramatically decreases, explain two possible effects this could have on other populations in the food web.
If producers contain 10,000 units of energy, approximately how much energy would be available to the primary consumers using the 10% rule?
10,000 × 10% = 1,000
A bee collects nectar from a flower while transferring pollen between flowers, helping the plant reproduce. Identify the type of species interaction and explain how both organisms benefit.
Mutualism. The bee gets food from the flower, while the flower benefits because the bee transfers pollen, helping the plant reproduce.
How could deforestation affect both biodiversity and food webs within an ecosystem?
Deforestation destroys or changes habitats, which can reduce the number of species living in an area and therefore reduce biodiversity. It can also remove producers and food sources, disrupting food webs and affecting organisms at multiple trophic levels.
Explain how a change in an abiotic factor, such as rainfall or temperature, could affect multiple organisms within an ecosystem.
A change in rainfall could reduce the amount of water available to plants. This could reduce plant growth, meaning herbivores have less food available. This could then affect predators that rely on those herbivores for food.
In the food chain grass → grasshopper → frog → snake, which organism is the producer?
Grass
An ecosystem has 50,000 kJ of energy stored in its producers. Using the 10% rule, calculate approximately how much energy would be available to secondary consumers. Explain why this amount is much smaller than the energy available to producers.
Producers: 50,000 kJ
Primary consumers: 5,000 kJ
Secondary consumers: 500 kJ
A new predator enters an ecosystem and begins eating a native species. Predict how this could affect the prey population, the predator population and at least one other species in the ecosystem. Explain your reasoning.
The native prey population would likely decrease because it is being eaten by the new predator. If there is plenty of prey, the predator population could increase. Other species could also be affected; for example, predators that normally eat the native prey may have less food available, while organisms that compete with the prey for resources may increase.
A new invasive plant is introduced into an ecosystem. It grows rapidly and takes water, sunlight and nutrients away from native plants. Explain how this could create a chain reaction through the ecosystem, including effects on herbivores and predators.
The invasive plant could cause native plant populations to decrease because they have less access to resources. Herbivores that rely on the native plants may then have less food and their populations could decrease. Predators that rely on those herbivores may also have less food, potentially causing their populations to decrease. The invasive plant could therefore cause changes across multiple trophic levels.