list one key similarity and one key difference between a vaccine and the pathogen it protects against

How can scientists test their ideas about the origin of the universe if they can't physically interact with or study?

The cluster of developing cells from conception until birth is called an

Graded assignment lab report answer the questions below. which combinations of substances resulted in a chemical change? for each metal that participated in a chemical change, write the type of metal it is, based on your examination of the periodic table. were there any metallic compounds that did not react with either the acid or the base? write the type of metal, based on your examination of the periodic table. make a general statement about the reactivity of the metals in this experiment.