Linearity assumption in Linear Regression

This is actually a good question. For a categorical variable, can the model say that some veles are significant, some levels are not. Typically after a regression we look at the ANOVA (Analysis of Variance) table. There we have 1 row per independent variable. In other words, in My example we will see a single row corresponding to the variable COLOR (as opposed to say 2 rows for I_green and I_blue).