the smallest building blocks of all living things

In science class, we had to study cells from a frog.

the act or process of growing

Lifting weights and eating high-protein foods, like chicken, can help with muscle development.  

very rare and in danger of dying out completely

Orangutans are endangered mostly because people have cut down many of the forests where they live. 

the state of being kept in a place (like a prison or cage) and not being able to leave

The tiger has lived in captivity for years, and many people say it should be set free.

places where plants or animals naturally live or grow

Birds’ habitats include the trees where they build their nests.