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An important early step in our understanding of innate immunity in vertebrates came from research studying fruit flies.

• True

• False

Which of the following is NOT an organ of the immune system?

• Spleen

• Thymus

• Thyroid

• Red bone marrow

• Tonsils

Helper and Inducer cells are subcategories of ___ cells.

A group is considered monophyletic if ___.

• not all descendants of the common ancestor are included.

• all members of the group share a common ancestor that is included in the group.

• the group does not contain the most recent common ancestor.

• all members share homoplastic traits.

In mammalian kidneys, blood in the vasa recta and fluid in the loop of Henle flow in opposite directions to create a __ multiplier system.

• Reversible

• Exponential

• Countercurrent

• Homeostatic