These characteristics are useful because they help the cell to carry out its normal activities
Answer:
Stimulus
Explanation:
this happens when the external effects in the environment affects the a body internally
Human and apes have 5 fingers that are used for grasping objects, so they have the same function, but they also have a common ancestor and are closely related, that means that this is an example of homologous structures. In evolutionary biology, the term homologous structures means that there are organs and skeletal elements of animals and organisms, that by virtue of their similarity, suggest their connection to a common ancestor.
Neurotransmitters is the word you're looking for.