Which of these is not a physical barrier of your body to disease? skin

mucous membranes

chemicals

hair

Answer and I will give you brainiliest

Average annual precipitation and are the two major features that define the biomes on earth.

25) a student takes four samples of a white crystalline solid and places each in a well plate. on top of each sample, she carefully places 20 drops of clear mystery liquids a, b, c and d. her results for each well are: liquid a: the solid dissolves quickly. liquid b: the solid appears unchanged. liquid c: a brownish colored liquid is produced. liquid d: fizzing occurs and the well becomes warmer. in which well does a physical change occur?

An easy way to calculate the amount of energy available at each level is to what?