Answer:
The correct answer would be C. The tortoises provided evidence that different species have adaptations suited to their particular environments.
Darwin observed that how different environment on different island lead to the development of different species as a result of adaptations and natural selection.
For example, tortoise inhabiting well-watered islands which used to have short and cropped vegetation had developed a dome-shaped shell.
In contrast, the tortoise inhabiting the arid islands had developed saddle-shaped shells. It is because they needed to stretch their necks in order to reach branches of cactus and other vegetation available in the area.
Consequently, they developed long necks and high peak to the front edges of their shells. It made it possible for them to stretch their heads vertically.
Answer:
Voltage-gated Ca2+ channels
Explanation:
Modulation of Ca+2 channel Epinephrine also causes an increase in cAMP that stimulates PKA that is protein kinase A, which in turn phosphorylates the voltage-gated Ca+2 channel that is the L channel. This phosphorylation results in a protein conformational change that enchances the channels activity.
Valves, they are like flaps of muscle that keeps the blood in its place util its ready to be pumped along.
