Humans have come to think of bacteria as harmful pathogens that always do harm. However, this is not always the case. Based on the nitrogen cycle, explain why farmers are dependent on bacteria for their crops and what would happen if farmers were able to remove all bacteria from their soil?

Which of the following is true of natural population a.) populations are all the individuals of a species living in a defined area b.) populations are all uniform in size c.) viable populations exhibit little, if any, genetic variation

Match the following terms describing electrical events with the correct phases of the cardiac cycle. the ventricular muscle cells depolarize at the start of this phase. during this phase, na+ entry through the funny channels causes the pacemaker potential of sa nodal cells to gradually become less negative until it reaches threshold. the ventricular muscle cells repolarize right before this phase. the cytosolic concentration of calcium in the contractile cells of the ventricle is highest during this phase. a. isovolumetric relaxation b. ventricular ejection c. isovolumetric contraction d. ventricular filling

Aflashlight battery is an example of a) potential energy b) kinetic energy c) thermal energy d) solar energy