Excitation-contraction coupling refers to the events that link the action potentials on the sarcolemma to activation of the . it begins with the arrival of the at the neuromuscular junction.

Excitation-contraction coupling refers to the events that link the action potentials on the sarcolemma to activation of the Ca+ channels . It begins with the arrival of the action potential at the neuromuscular junction.

Explanation:

The action potential travels from the neuron and it is transmitted to the muscle through the neuromuscular junction, which is the place where the neuron and the muscle join. Once that the action potential is in the muscle this will open Ca+ channels in order to let the Ca+ enter the muscle fiber and produce the contraction in the sarcomere.

the answer for apex is "1 and 6"

the two answers are a, the population of birds with large beaks will increase on the island, and c, the trait for large beaks will be passed on to future generations through natural selection. the reason for that is because if the birds that have beaks developed for eating small seeds lose all of their food, they will go hungry and eventually starve because they physically cannot eat the large seeds, therefore making the population of large beaked birds higher. also, if the trait of large beaks are dominant on the island over small beaks, then over time the large beaked birds will reproduce more and more, while the smaller beaked birds will reproduce less and less because they can't survive with the food provided. that leads to the trait of small beaks disappearing and the trait of large beaks taking over the island.