Sodium is an example of an alkali metal. The alkali metals are found in the leftmost column of the periodic table, known as Group 1. Use the interactive periodic table to explore the properties of the following alkali metals: lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs). The animations demonstrate a chemical property common to alkali metals: they react with water. How does the reactivity vary among this group of elements? Why might patterns like this be useful to scientists?

parasites can detrimentally affect their host, but also must not allow their host to die before they can complete their life cycle. some parasites have complex life cycles with many different hosts, and have had to find ways of persisting in many different environments during the change from one host to another. ectoparasites live outside the body of the host, and can more easily  disperse, but are  more exposed to predators, parasites, parasitoids. endoparasites live inside the body of the host, and are therefore protected from the outside environment. but they can be  attacked by the host's immune system. they have therefore developed  mechanisms for dispersal such as  complex life cycles.

wheres the answers ?

what statement best describes the difference between the sympathetic and parasympathetic nervous systems?

the sympathetic nervous system prepares the body for intense physical activity and is often referred to as the fight-or-flight response. the parasympathetic nervous system has almost the exact opposite effect and relaxes the body and inhibits or slows many high energy functions.

the question isn't complete here so i can't right an answer '_'