Which of the following statements is correct?
a. most animal phyla belong to the clade radiata.
b. eumetazoans have three embryonic tissue layers.
c. the origin of all extant animal phyla can be traced to the cambrian explosion.
d. all animals share a common ancestor.
e. sponges are diploblastic animals.

Which of the following is a macronutrient? carbohydrates lipids amino acids all of the above

Which is an advantage of having memory cells when a pathogen is encountered for a second time. a) the memory cells are what proliferate into clones of cells in response to the binding of an antigen. b) memory cells are vital to the primary immune response in that they immediately recognize pathogens even at the first encounter. c) memory cells are essentially effector cells that are short lived and attack antigens even without having a receptor specific to that antigen. d) it ensures that more lymphocytes with a receptor specific to a particular antigen will be present than in a host that had never encountered that pathogen.

What maintain homeostasis when a persons internal body temperature is 97.5°f