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Which animals lack a true circulatory system?a. cnidarians $\quad$ c. nematodesb. flatworms $\quad$ d. All of these are correct.
Which one of these would you expect to be part of a closed, but not an open, circulatory system?a. ostia $\quad\quad\quad\quad$ d. heartb. capillary beds $\quad$ e. All of these are correct.c. hemolymph
Which animal has a closed circulatory system?a. earthworm $\quad$ b. grasshopper $\quad$ c. hydra $\quad$ d. sea star
All vertebrates havea. a closed circulatory system.b. a heart with at least three chambers.c. a two-circuit circulatory pathway.d. All of these are correct.
A major difference between arteries and veins is thata. arteries always carry oxygenated blood; veins never do.b. arteries carry blood away from the heart; veins return blood.c. only arteries have valves.d. veins feed blood into capillaries.
In which animal does aortic blood have less oxygen than blood in the pulmonary vein?a. frog $\quad\quad$ d. fishb. chicken $\quad$ e. All of these are correct.c. monkey
In humans, blood returning to the heart from the lungs returns toa. the right ventricle. $\quad$ d. the left atrium.b. the right atrium. $\quad\quad$ e. both the right and left sides of the heart.c. the left ventricle.
All arteries in the body contain oxygen-rich blood, with the exception of thea. aorta. $\quad\quad\quad\quad\quad\quad$ c. renal arteries.b. pulmonary arteries. $\quad$ d. coronary arteries.
Systole refers to the contraction of thea. major arteries. $\quad$ d. major veins.b. SA node. $\quad\quad\quad$ e. All of these are correct.c. atria and ventricles.
Which of these is an incorrect statement concerning the heartbeat?a. The atria contract at the same time.b. The ventricles relax at the same time.c. The atrioventricular valves open at the same time.d. The semilunar valves open at the same time.e. First the right side contracts, and then the left side contracts.
Label this diagram of the heart.
Which of the following is not a formed element of blood?a. leukocyte $\quad$ c. fibrinogenb. eosinophil $\quad$ d. platelet
Which of these is an incorrect association?a. white blood cells—infection fightingb. red blood cells—blood clottingc. plasma—water, nutrients, and wastesd. red blood cells—hemoglobine. platelets—blood clotting
Water enters capillaries on the venous end as a result ofa. active transport from tissue fluid.b. an osmotic pressure gradient.c. higher blood pressure on the venous end.d. higher blood pressure on the arterial side.e. higher red blood cell concentration on the venous end.