How many distinct stages must occur between the point when light first encounters chlorophyll and the point at which
can be used as energy by the plant?
two
three
five
eight

1. beginning with all chambers of the heart in the "relaxed" phase, describe the cardiac cycle in mammals, with systole and diastole of the atria and ventricles. for each time point in the cycle you select, state the following: • whether the atria and ventricles are contracting or relaxing • whether the av valves and semilunar valves are closed or open • whether the pressure in the atria and ventricles is high or low