In twitch summation, a) the muscle fiber is stimulated again before the filaments have completely returned to their resting position b) stronger muscle contractions occur but stronger action potentials do not uoccur c) a second action potential occurs in the muscle fiber, before the first action potential is finished d) both a and b are correct e) all of the above are correct

the correct answer is E

Explanation:

In the sum of contractions, the action potentials are sent more frequently but not with greater intensity, this is because in the motor plate the neurotransmitters do not cease and continue to bind to their receptors, promoting the stimulation of muscle fiber, once the muscle fiber contracts, before returning to its depolarized or resting moment a new contraction begins, some researchers maintain that these contractions are stronger but that the action potential that stimulates them does not refer to more power.

correct answer is option a.

tropopause, stratopause and mesopause have all in common aspect that is point of maximum temperature in its layer of the atmosphere. all layers of atmosphere observe abrupt change in temperature. tropopause is the boundary between troposphere and stratosphere. stratopause is the boundary between stratosphere and mesosphere. mesopause is the boundary between mesosphere and thermosphere. these all boundaries are ranges between altitude of 0 to 80 km.

a. seed plant structure. 1. the three main plant organs are roots, stems, and leaves. a fourth kind of tissue, meristematic tissue, is responsible for plant growth. meristematic tissue is the only plant tissue that produces new cells by mitosis. plants can lose water out of their leaves as they exchange gases with the air

explanation: