An independent variable is what influences changes in the dependent variable. So you can say that it is the variable that we chance. It is called <u>INDEPENDENT</u> because it is not affected by the dependent variable.
In this case, the speed of the electric fan is not affected by the graham cracker, but the speed of the electric fan AFFECTS the graham cracker.
(Although the biggest clue is the variable that is manipulated or changed by the experimenter.)
Microvilli are hairs that aid in absorption of nutrients. In the small intestine, these cells contain microvilli, which are tiny hair-like projections that increase nutrient absorption. These projections increase the surface area of the small intestine allowing more area for nutrients to be absorbed.