How does a law differ from a theory?
a law is a theory that has been proven to be true and universal
a theory is a group of hypotheses that prove a law is true.
a law is a statement of fact, but a theory is an explanation
a theory is a proposed law that has not yet been peer reviewed.

A law is a statement of fact but a theory is an explanation.

Explanation:

A law is in general a universally accepted fact. It remains true and the same in any part of the world it takes several years of experimentation to develop a law.  

A law is a statement that cannot be challenged at the present point of time with all its technological advancements. A theory is different from a law. It is an explanation of facts.  

Most acceptable one among several explanations becomes a theory. A theory doesn’t have a universal nature  like that of a fact.  

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.

answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation: