As a person exercises, carbon dioxide (co2) levels in the blood increase. this causes the nervous system to signal which of these systems to respond? a digestive and immune b immune and respiratory c respiratory and circulatory d circulatory and endocrine

Which of the following is the best definition of a eukaryota? a. a one-celled organism that does not have a membrane-bound nucleus b. a one-celled organism that does not have a cell wall c. an organism whose cells each contain a membrane-bound nucleus d. an organism whose cells each have a cell wall