Help me please!!! What does this picture mean

Aneuron is stimulated with an electric pulse. the action potential is detected at a point 3.70 cm down the axon 0.0052 s later.when the action potential is detected 7.20 cm from the point of stimulation, the time required is 0.0063 s. what is the speed of the electric pulse along the axon? (why are two measurements needed instead of only one? )

Photosynthesis converts light energy to chemical energy. which molecules are the end product of this transformation of energy in this reaction?

At which location in earth’s interior does the top density continue to increase as thickness decreases?