Select all that apply.

which of the following are characteristics of prokaryotes?
single-celled structure
flagella for movement
distinct nucleus
membrane-bound organelles

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.