Opening and closing of the heart valves is caused by ________.
A. gravity
B. breathing
C. valves contracting and relaxing
D. osmotic gradients
E. pressure gradients
Answer: E
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What state had the best-trained and most up-to-date military force in Europe, despite being smaller than those of its rivals?
A. Great Britain B. Russia C. France D. Prussia
Which of the following is NOT a normal component of lymph?
A) plasma proteins B) red blood cells C) water D) ions
In the male, sperm cells, before leaving the body, travel from the testes in which sequence?
a. ductus deferens, epididymis, urethra, ejaculatory duct b. epididymis, ejaculatory duct, ductus deferens, urethra c. ejaculatory duct, epididymis, ductus deferens, urethra d. epididymis, ductus deferens, ejaculatory duct, urethra
What do semilunar valves prevent?
A) Semilunar valves prevent the flow of blood into the ventricles during atrial contraction. B) Semilunar valves prevent backflow of blood into the atria. C) Semilunar valves prevent backflow of blood into the ventricles. D) Semilunar valves prevent backflow of blood into the veins. E) Semilunar valves prevent backflow of blood into the coronary vasculature.