In a certain species of plant, flowers can be purple or white. When to plant with white flowers (P1) is crossed with a plant with purple flowers (P2), all the offspring have purple flowers

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.