Habitats and Ecosystems — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. A polar bear has thick fur to stay warm in the tundra.
The tundra is freezing cold most of the year, and a polar bear's thick layer of fur traps body heat next to the skin so it can stay warm even on the ice.
2. A cactus has sharp spines instead of leaves to save water.
A cactus has to hold on to every drop of water in the desert. Its sharp spines lose far less water than wide leaves would, and they also keep thirsty animals from biting it.
3. Fish have gills that help them breathe underwater.
Underwater there is no air to breathe, so fish use special slits called gills to pull oxygen out of the water.
4. A bird of prey uses sharp talons to catch food.
Birds of prey, like hawks and eagles, swoop down and grab their food with strong, curved claws. Those sharp claws are called talons.
5. Grassland animals often run fast to escape predators.
Open grasslands have very few places to hide, so animals like gazelles and zebras stay safe by running fast to escape the predators that hunt them.
6. A adaptation is a body part or behavior that helps an animal survive.
Long roots on a cactus, gills on a fish, and white winter fur on a fox are all examples of body parts or behaviors that help animals stay alive. The word for any such helpful trait is adaptation.
7. Desert animals are often active at night when it is cooler.
Days in the desert are blazing hot, so many animals rest in the shade and come out to hunt and search for food at night, when the air finally cools down.
8. Ocean plants called algae produce much of the world's oxygen.
Tiny ocean plants called algae use sunlight to make food and release oxygen, and because the oceans are so huge, they end up producing a large share of the world's oxygen.
9. Decomposers return nutrients to the soil so new plants can grow.
When decomposers break down dead leaves and animals, they release nutrients back into the soil. Those nutrients feed new plants and keep the cycle going.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
thick blubber
→ ocean animal
ocean animal
long roots
→ desert plant
tundra hunter
white fur
→ tundra hunter
desert plant
webbed feet
→ pond bird
pond bird
Each adaptation matches its habitat: thick blubber keeps an ocean animal like a whale warm in cold water, white fur lets a tundra hunter blend into the snow, long roots reach deep for water in the desert, and webbed feet help a pond bird paddle through water.