Life Cycles — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. A chicken life cycle begins when a hen lays an egg.
A chicken's life cycle starts when a hen lays an egg. The baby chick grows inside the egg until it hatches.
2. The hen keeps the egg warm by sitting on it, which is called incubation.
Incubation is the special word for keeping eggs warm so the babies inside can grow. The hen's body heat does this job naturally.
3. A chick breaks out of its shell using a tiny bump called an egg tooth.
The egg tooth is a small hard bump on a chick's beak that works like a tiny tool for cracking the shell. It drops off a few days after the chick hatches.
4. A frog begins its life as a tiny egg in the water.
Frogs lay their eggs in ponds or streams, so a frog's life starts in the water. The eggs hatch into tadpoles that swim right away.
5. Tadpoles grow back legs first, then front legs.
A tadpole's back legs appear first because they are larger and used for hopping. The smaller front legs grow in later as the frog becomes ready to leave the water.
6. A young chicken is called a chick until it grows adult feathers.
A baby chicken is called a chick while it still has fluffy down. Once adult feathers grow in, it becomes a young hen or rooster.
7. An adult frog can live on land and in water.
Adult frogs have lungs so they can breathe air on land, but their skin also lets them take in air underwater. That is why they live in both places.
8. A male chicken is called a rooster.
Roosters are the male adult chickens. They do not lay eggs but they often crow and help protect the hens.
9. Frogs catch insects with their long, sticky tongue.
A frog flicks out its long tongue so fast that bugs stick to it. The sticky tongue pulls the insect back into the frog's mouth to eat.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
egg (chicken)
→ has a hard shell and needs warmth
breathes with gills and swims
chick
→ covered in soft down feathers
has a hard shell and needs warmth
tadpole
→ breathes with gills and swims
hops on land and catches insects
adult frog
→ hops on land and catches insects
covered in soft down feathers
Each stage has its own features: chicken eggs need warmth to hatch, chicks wear fluffy down, tadpoles use gills underwater, and adult frogs hunt bugs on land. Matching each description to the right stage shows how animals change as they grow.