1. What does the abbreviation 'ATP' mean? Is that food+oxgen=energy? 2. I don't really know what 'respiration' means? 3. There are 7 categories of classification: Kingdom, phylum, class, order, family, genus, species. But what's the difference among 'class' ,'order' and 'family'? What's the difference between 'genus' and 'species'. In other words, what are the relations among those words, or what does each word represent? Thanks for replies.