Question

When using terms such as coelomates and pseudocoelomates, a “grade” is _________.?

Answer 1

In this case, a grade refers to a group whose members share major or key biological characteristics.

Answer 2

When using terms such as coelomates and pseudocoelomates, a “grade” is a group whose members share key biological features. So, these organisms don't share just any or few biological features, but rather those most important ones on which their lives depend. They don't need to have a common ancestor or descendant, but rather common features they all share.