The first heart sound, "lubb," is caused by the . The first heart sound, "lubb," is caused by the . closing of the atrioventricular valves regurgitation of the atrioventricular valves closing of the semilunar valves blood flowing into the ventricles

Scientists studied reproduction in the new zealand mud snail to answer the question, “are there benefits to reproducing sexually or asexually? ” which of these hypotheses would least likely aid the scientists as they worked to answer the question? sexual reproduction is advantageous over asexual reproduction because it reduces the rate of mutation accumulation. asexual reproduction is advantageous over sexual reproduction because it allows the snails to produce more offspring. sexual reproduction is advantageous over asexual reproduction because it allows for snails to have increased genetic variation. asexual reproduction is advantageous over sexual reproduction because it decreases the snails’ need for social