Which ones are microscopic?

Which part of the neuron below is indicated by the arrow, and what is its function? hormones send chemical signals throughout the body to regulate other body processes. hormones are chemical signals that are sent throughout the body to regulate other body processes. hormones send electrical signals throughout the body to regulate other body processes. hormones are electrical signals that are sent throughout the body to regulate other body processes.

When a population split into two subgroups what is most likely to cause the subgroups to develop different traits?

The part of the eye that closes and opens to let light in is .