Independent variables: a variable that is changed or controlled in a scientific experiment. It represents the cause or reason for an outcome. Independent variables are the variables that the experimenter changes to test their dependent variable.
dependent variable: the possible outcome of the experiment; the effect. It depends on what happens to other variables in the experiment. The dependent variable is basically the part that you are changing.
The meaning of the scarce is insufficient for demands.
The scarcity of the food is determined by the availability of the food in the market. In case, the food available in the refrigerator is easily available in the nearby stores, then it is not scarce. In case, the food available in the refrigerator is not readily available in the market, then it is scarce.
The inactive X is called also as Barr body. It stains much darker than the other chromosomes because of the fact that it is inactive. By being inactive it means that the chromatin of that chromosome is very compact because it is not used for gene expression. Being so compact, all the staining is concentrated creating a darker body.