The three steps of the nitrogen cycle in order, starting with nitrogen gas in the atmosphere, are nitrogen fixation, denitrification, and nitrification.

nitrification, nitrogen fixation, and denitrification.

nitrogen fixation, nitrification, and denitrification.

denitrification, nitrification, and nitrogen fixation.

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

What are the doorways into and out of cells, attached to the membrane, and built in the rough er.

Do you think the gene eef1 alpha1 supports cell theory? explain your response.