Habitats and Ecosystems — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. A food web is made of many food chains that overlap.
A food web looks like a spider's web because many food chains cross and connect, showing that one animal often eats — and is eaten by — several others.
2. Organisms that eat dead material and recycle nutrients are decomposers.
The word "decomposers" comes from "decompose," meaning to rot and break apart, which is exactly what these organisms do to recycle nutrients back to the earth.
3. A omnivore eats both plants and animals.
The prefix "omni-" means all, so an omnivore eats all kinds of food — both plants and meat — like bears, raccoons, and people.
4. Coral reefs provide shelter for thousands of ocean species.
Coral reefs are full of cracks, holes, and crevices where small fish and sea creatures hide from predators and lay their eggs safely.
5. Removing one species from a food web can disrupt the whole ecosystem.
Every species has a job in the food web; pulling one out is like removing a thread from a net, so the whole system gets thrown out of balance.
6. Sunlight, water, and soil are nonliving parts of an ecosystem.
Soil is made mostly of tiny rock pieces, sand, and clay, which never breathed or grew, so it counts as a nonliving part of an ecosystem.
7. In the ocean, tiny floating plants called phytoplankton start many food chains.
Phytoplankton are microscopic plant-like drifters near the ocean surface that use sunlight to make food, becoming the producers tiny fish and even huge whales depend on.
8. A primary consumer eats producers directly, like a deer eating grass.
"Primary" means first, so a primary consumer is the first eater in the food chain — usually a herbivore that munches plants right after the producers grow them.
9. Hawks and wolves are at the top of their food chains.
Hawks and wolves are apex predators with no natural enemies hunting them, which puts them at the very top of their food chains.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each organism to its role in a food chain.
oak tree
→ producer
decomposer
mushroom
→ decomposer
secondary consumer
grasshopper
→ primary consumer
producer
wolf
→ secondary consumer
primary consumer
An oak tree makes its own food from sunlight (producer), a mushroom breaks down dead matter (decomposer), a grasshopper eats plants (primary consumer), and a wolf hunts those plant-eaters (secondary consumer).