1. Nuclear fusion
2.
Radiation
3. _
Star
4. __Universe
5.
The Sun
Vocabulary words

they are known to reach a speed of 21 miles per hour

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.

several tissues working together form an organ, and several organs together make up an organisms.

the group of cell that carries out special jobs are tissue.