Which statement best describes a human influence on the biogeochemical cycles?
a. increased eutrophication caused by high levels of nitrogen and phosphorous
b. increased nitrates available due to inaccurate methods of denitrification
c. increased global warming due to alternative energy sources
d. increased amount of water that is available to freshwater ecosystems

Define the apical impulse and describe its normal location, size, and duration. which abnormal conditions may affect the location of the apical impulse? explain the mechanism producing normal first and second heart sounds. describe the effect of respiration on the heart sounds. describe the characteristics of the first heart sound and its intensity at the apex of the heart and at the base. describe the characteristics of the second heart sound and its intensity at the apex of the heart and at the base.