In the experiment, "Do white cats eat more than black cats?" the independent variable would be: the color of the cat.
how much each cat weighs.
how much food each cat eats.
the temperature of the food.

thrombocytopenia, which is a deficiency in blood platelets, can cause bleeding and bruising in the dermis similar to senile purpura. other possible causes include: exposure to ultraviolet rays and aging skin are common causes of senile purpura. senile purpura may also be a sign of collagen loss in the skin and bones.