Scissors are considered a compound machine because
they are made of two inclined planes
they are made of a lever and a wedge
they make work easier

cell differentiation  is how generic embryonic  cells  become specialized  cells. this occurs  through a process called gene expression. gene expression is the specific combination of genes that are turned on or off (expressed or repressed), and this is what dictates how a  cell  functions.

explanation:

iron would move it is magnetic there is a mag field around the current in the wire

one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.