How can the two chromosomes that make up a homologous pair differ

Will someone me with this.. specialized cells which perform a particular function form: tissues organs or organism

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.

What function does the limb sever in each animal? how are the limb bones of the four animals similar? based on these similarities what can be inferred about the evolution of the four animals.