It is 2: 00 a. m. and michelle is home by herself. her dog begins to bark loudly and the hair on the back of her dog's neck is standing up. michelle then hears banging on her front door. michelle starts to sweat and her heart begins to beat faster and faster. michelle's nervous system has kicked in.

The speed of  sound:   sound travels  at different speeds depending on what it istraveling through. of the three mediums (gas, liquid, and solid)  sound waves travel the slowest through  gases, faster  through  liquids, and fastest  through  solids.

The main role of dna in the  cell is the long-term storage of information. it is often compared to a blueprint, since it contains the instructions to construct other components of the  cell, such as  proteins  and rna molecules.the main function of rna is to carry information of amino acid sequence from the genes to where  proteins  are assembled on  ribosomes  in the  cytoplasm. mark brainliest, my work is good.