Contain structures that regulate and perform life functions.
The deeper down you get, the colder the water is
One major reason for exploring extreme environments is to find new resources. An example of a resource is the search for a new antibiotic. Extreme environments have rare species endemic to the regions which can offer different insights from the normative environment we are used to.
No, I would not. This is because the risk of death is higher in an extreme environment. Example of these risks are deadly diseases or harsh climate. The body may be unable to adjust to the extreme environment hence may be unable to restore homoeostasis; such as in restoring body heat in extremely cold environments hence leading to hypothermia.
There are four principles at work in evolution—variation, inheritance, selection and time. The theory of evolution by natural selection, first formulated in Darwin's book "On the Origin of Species" in 1859, is the process by which organisms change over time as a result of changes in heritable physical or behavioral traits.
Flight; fight
The sympathetic is used to speed things up, stopping things like digestion in order to supply more blood to the heart and lungs, while the parasympathetic does the opposite; digesting food and working on internal things while the heart rate and breathing rate slow.