For an animal to move in one direction, its muscles must do all of the following except

a. overcome the effects of friction.
b. exert a force in the opposite direction.
c. spend energy.
d. overcome the effects of gravity.
e. exert a force in the same direction.

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

Each pair of clay balls represents two planetesimals. if each planetesimal is composed of the same material and is separated he the same distance, which pair experiences the frayed gravitational attraction?

Recombinant dna is the merging of dna from unrelated organisms to create new genetic varieties is assembled in the lab from mononucleotides was part of the green revolution of the 1960s is pollination of one plant by another of the same species is cross-pollination of one plant by a different species