community of organisms where each member is eaten by another
The cactus, the bat, and the owl are parts, or links, in one desert food chain. In a food chain, each living thing transfers its energy to the living thing that eats it.
To determine what's important, you focus on what matters. One way to determine what's important is to summarize, or tell only the most important information.
Many long words begin with a prefix, or a short word part, like dis- and un-. Many of these English prefixes came from Latin, Greek, or Old English. Sometimes knowing the meaning of the prefix can help you predict the meaning of the word.