Papillary muscles prevent the AV valves from prolapsing (bulging) excessively into the atria when the ventricles contract. True False

True

Explanation:

Papillary muscles are the muscles that project out from the walls of the ventricles of the heart. These muscles are attached to the AV valves with the help of chordae tendineae. During the contraction of ventricles, the higher blood pressure closes the AV valves by driving the edges of these valves towards each other. At this time, the contraction of Papillary muscle pulls on and makes the chordae tendineae rigid and right. This does not allow the cusps of the AV valves to ever into the atria in the response to higher blood pressure in ventricles.

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".

i'd have to say the answer is probable the second option "the geosphere interacting with the atmosphere"