B cells must accomplish double recognition:
They must simultaneously recognize self and nonself to be activated.
Indicate whether the statement is true or false
FALSE
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If a person's cornea is flatter than normal, this person is
A) hypopic. B) astigmatic. C) presbyopic. D) myopic. E) hyperopic.
The hormone controlling erythropoiesis is produced in what organ?
a. pancreas. b. brain. c. heart. d. kidney. e. intestine.
The pH of the blood primarily depends upon a normal concentration of:
A) hydrogen ions. B) sodium ions. C) magnesium ions. D) calcium ions.
You are dissecting a species of amphibian that has just been discovered in the rainforest. You find a blood vessel where the blood travels at a low pressure and velocity. If the frog is in an upright position, blood flow through this vessel would also be against gravity. Anatomically, what do you expect of this blood vessel?
A. Valves that allow only one-way flow of blood B. Large wall to lumen ratio C. A thick muscular wall D. A high degree of compliance E. All of the answers are correct