The semilunar valves prevent the backflow of blood into the atria when the ventricles are contracting. the semilunar valves prevent the backflow of blood into the atria when the ventricles are contracting. a. true b. false

In the desert, saguaro cacti, owls, horned lizards, and fire ants all share the same space. which of the following can be considered a population? question 9 options: all plants in the same area all cacti in the same area all species in the same area the lizards and the ants