Leaukocytes role in the process of antibody formation ( t and b cells)

According to the cladogram, which organisms have roundworms as a common ancestor?

Select the situation bellow that would produce a total displacement of zero. a. a trip to the moon and then to mars b. a horse galloping from one end of a field to another c. the criss-crossing path of a bug as it flies from flower to flower d. a round-trip ride to school and back

Which of the following describes a difference when gram-positive bacteria are compared to gram-negative bacteria?