Acetylcholine (ach) affects muscle action, learning, and memory. endorphins are natural opiates released in response to pain and exercise. drugs and other chemicals affect brain chemistry at synapses. agonists increase a neurotransmitter's action, and may do so in various ways. antagonists decrease a neurotransmitter's action by blocking production or release.

amber has allowed scientists to study dna that has been preserved over millions of years.

question: which statement best describes the different properties of metals?

answer: they are shiny and bend without breaking.

since metals have certain characteristics properties, they include the following: they are ductile, malleable, shiny, hard, lustrous, flexible and they are good conductor of heat and electricity. so therefore, metals are not dull and they are not non-flexible as listed. instead, they are shiny and flexible.

hope this , have a good day. c;