What are the names of the four chemical elements that make up amino acids?

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? )

This aquarium exhibits biotic and abiotic factors in an aquatic environment. one of the abiotic factors is

How does the carbon cycle involve an exchange of carbon