An ecosystem is a community of living things (plants, animals, fungi, microbes) interacting with each other and their physical environment. Energy flows through an ecosystem starting with producers (like plants), which use sunlight to make their own food through photosynthesis. Consumers eat other organisms for energy — herbivores eat plants, carnivores eat other animals, and omnivores eat both. A food web shows how many food chains connect and overlap, since most animals eat more than one type of food. If one population changes (like a drought reducing plant numbers), it can affect many other species connected to it in the web.
Example
In a food web, grass is eaten by rabbits, rabbits are eaten by foxes, and foxes are eaten by nothing (a top predator). If a disease wipes out most rabbits, foxes might struggle to find food, and grass might grow back more since fewer rabbits are eating it.
Key terms
Producer:
An organism, like a plant, that makes its own food using sunlight.
Consumer:
An organism that gets energy by eating other organisms.
Food web:
A network of connected food chains showing feeding relationships in an ecosystem.
Questions
1. An ecosystem includes:
Only plants
Living things and their environment interacting
Only animals
Only rocks
2. A producer makes its own food using:
Water only
Sunlight
Other animals
Rocks
3. A consumer gets energy by:
Making its own food
Eating other organisms
Doing nothing
Absorbing sunlight directly
4. A herbivore eats:
Only meat
Only plants
Both plants and meat
Nothing
5. A carnivore eats:
Only plants
Only other animals
Sunlight
Rocks
6. An omnivore eats:
Only plants
Only meat
Both plants and animals
Neither
7. A food web shows:
One single food chain
Connected, overlapping food chains
Only producers
Only predators
8. Plants make food through a process called:
Respiration
Photosynthesis
Digestion
Evaporation
9. In a food chain grass → rabbit → fox, the fox is a:
Producer
Herbivore
Carnivore
Omnivore
10. In the same chain, the rabbit is a:
Producer
Herbivore
Carnivore
Decomposer
11. If a disease reduces the rabbit population, the fox population is likely to:
Increase immediately
Struggle for food and possibly decrease
Be completely unaffected
Instantly become extinct
12. If rabbit numbers drop, grass is likely to:
Also decrease
Grow back more since fewer are eaten
Disappear completely
Turn into rabbits
13. A food web is more realistic than a single food chain because:
Most animals eat only one food source
Most animals eat more than one type of food
Food chains never connect
Ecosystems have no connections
14. Energy in an ecosystem originally comes from:
The soil
The sun
Animals
Water
15. Removing a top predator from an ecosystem could cause:
No change at all
Prey populations to grow unchecked, affecting other species
Instant collapse of all producers
Nothing, since predators are unimportant
16. Why are producers essential to almost every food web?
They are the ultimate energy source that consumers rely on, directly or indirectly
Producers don't actually provide energy
Only carnivores matter in a food web
Producers only exist in oceans
17. A drought reduces plant growth in a grassland ecosystem. Which group is likely most immediately affected?
Top predators only
Herbivores that rely directly on those plants
No one, since droughts don't affect ecosystems
Only decomposers
18. Two food chains in the same ecosystem share a predator that eats from both. This illustrates:
Why food webs are more accurate than single food chains
That food chains can never connect
That the predator is a producer
That energy never flows between chains
19. Why is energy described as "flowing" through an ecosystem rather than being recycled?
Energy is used and lost (mostly as heat) as it passes from one organism to the next
Energy is created new at every level
Energy stays exactly the same amount forever within one animal
Energy never actually moves
20. A new predator species is introduced to an ecosystem with no natural competitors. This is likely to:
Have no effect on the food web
Significantly disrupt the existing balance of the food web
Immediately fix all ecosystem problems
Only affect producers
Answer key (parent copy)
1. Living things and their environment interacting
2. Sunlight
3. Eating other organisms
4. Only plants
5. Only other animals
6. Both plants and animals
7. Connected, overlapping food chains
8. Photosynthesis
9. Carnivore
10. Herbivore
11. Struggle for food and possibly decrease
12. Grow back more since fewer are eaten
13. Most animals eat more than one type of food
14. The sun
15. Prey populations to grow unchecked, affecting other species
16. They are the ultimate energy source that consumers rely on, directly or indirectly
17. Herbivores that rely directly on those plants
18. Why food webs are more accurate than single food chains
19. Energy is used and lost (mostly as heat) as it passes from one organism to the next
20. Significantly disrupt the existing balance of the food web