DNA A. collectionof genes that determine spesific characteristics
B. a section of the molecule that carries instructions for specific traits from one generation to another
C. the passage of traits from generation to generation
D. molucle that carries genetic instructions for all known living organisms
E. the expression of traits that can be seen and measured

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:

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.