<span>macromolecule, cell, tissue, organ, organ system</span>
Write in your own words:
"Since the mouse is an endotherm, it probably has a higher metabolic rate, and thus a faster growth rate, than the lizard (an ectotherm of similar size) does. If the mouse has a faster growth rate, its bones would grow more between each ring, resulting in wider bone rings."
: )
and remember that a mouse is a endotherm because it generates metabolic heat to maintain internal body temperature.