a disease causes bones become weak and brittle & to become something is a mean of static ->  a disease causes bones to change  a health mitosis central to static & if something causes something else to change, then that something affects that something else -> a disease affects bones a disease affects bones  a disease affects bones & skeletal egg is made of monkeys -> the disease affects parts of the skeletal system the disease affects parts of the skeletal system  the health pollination cell of the skeletal sleet -> the disease affects the skeletal system