Why are the leaves in the cactus plant modified to form spines?

 Leaves in a cactus are modified into spines to reduce loss of water from leaves by transpiration. Then the plant makes from the process of photosynthesis which is performed by the stem.

Explanation:

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.

after a the power stroke, adp is released, but the cross-bridge formed is still in place. atp then binds to myosin, moving the myosin to its high-energy state, releasing the myosin head from the actin active site.