Habitats and Ecosystems — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. Why do some desert animals have large ears?
A) To hear predators from miles away.
B) To release extra body heat and stay cool.
C) To collect rainwater for drinking.
D) To dig burrows in the sand.
Big thin ears, like a jackrabbit's, have lots of blood vessels close to the surface; heat escapes through that thin skin like a built-in radiator to cool the animal off.
2. Which is an example of two species helping each other?
A) A hawk eating a snake.
B) A bee pollinating a flower while collecting nectar.
C) A lion chasing a zebra.
D) A mushroom growing on a dead log.
Both species win in this partnership — the bee gets sweet nectar to make honey, and the flower gets its pollen carried away so it can make seeds.
3. What happens to an ecosystem when a new predator is introduced?
A) Prey populations may decrease quickly.
B) Producers will disappear first.
C) Decomposers will leave the area.
D) The weather will change.
Native prey have not learned to escape a brand-new hunter, so the predator can catch them easily and the prey numbers drop fast before they can adapt.
4. Which adaptation helps a duck survive in a pond habitat?
A) sharp claws for climbing trees
B) a long neck for reaching tall leaves
C) waterproof feathers and webbed feet
D) thick fur for cold winters
Waterproof feathers keep a duck dry and warm in the pond, while webbed feet act like paddles to push it through the water just like swim flippers do for a person.
Part B: Fill in the Blank
Write the correct answer on each line.
1. Animals that move to a warmer place for winter are said to migrate.
Migration is a long seasonal journey; geese, monarch butterflies, and whales all travel south in fall to escape the cold and find food, then return in spring.
2. A chameleon changes its skin color to blend in with its surroundings.
Special cells in a chameleon's skin can shift color to match a green leaf or a brown branch, hiding it from predators and helping it sneak up on insects.
3. Plants and animals in an ecosystem are dependent on each other to survive.
Plants give animals oxygen and food, animals scatter plant seeds and add fertilizer to soil — each side needs the other, which is what "dependent" means.
4. A beaver builds a dam across a stream, which creates a pond habitat.
A beaver dam is a wall of sticks and mud that blocks moving water, causing it to back up and flood the land into a calm pond where the beaver family is safe.
5. The process plants use to make food from sunlight is called photosynthesis.
"Photo" means light and "synthesis" means putting together, so photosynthesis is how green leaves combine sunlight, water, and carbon dioxide into sugary food.