1. Explain how your brain perceives the location and intensity of a stimulus like pain. (1 pt) 2. Say you are looking at a neuron with a higher concentration of K+ ions inside the cell than outside. When K+ channels are open, why is there no net diffusion of K+ ions across the membrane even though there is a large concentration difference inside vs outside cell? (2 pts) 3. There is a type of algae that create a red tide algal bloom in coastal waters. These algae also release a toxin that acts by blocking voltage-gated sodium channels, and some species of clams are affected by this toxin. Describe what effect this toxin would have on the clams and why. (2 pts) 4. Describe the movement of Na+ and K+ ions and the changes in Vm during the phases of an action potential [at rest, depolarization, repolarization/hyperpolarization, after hyperpolarization]. Include the opening and closing of voltage-gated sodium and potassium channels in each step. (2 pts) 5. Describe the role of myelin in action potential propagation and why the loss of myelin (for example, through multiple sclerosis) can lead to symptoms such as loss of motor control. (1 pt)