With age, muscles can become weaker. this is due to a. connections between nerves, which cause more pain and therefore less use b. damage from everyday use and injuries that accumulate over time c. disconnections between motor nerves and muscle fibers d. difficulties that occur during muscle growth and repair

Assume you were going to teach this information to a group of seventh graders. pick a title for your presentation that would make the seventh graders want to listen to you.

Why do you need two different circuits of blood vessels in your body?

Investigator a has biological specimens that are coded and linked to identifiers of the source individuals. investigator a provides the specimens to investigator b but does not provide the individual identifiers. investigator b agrees not to re-identify the source individuals. is investigator b's research using the biospecimens human subjects research according to the definition of human subjects research in the federal regulations?