A notochord is a:
A) tube for circulating water through gills.
B) dorsal nerve cord.
C) ventral nerve cord.
D) tough yet flexible support structure.
E) specialized tail adapted for swimming.
Answer: D
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Acetylcholine induces vasodilation in intact blood vessels because _____ is released from the _____.
A. nitric oxide, endothelium B. nitric oxide, smooth muscle layer C. nitric oxide, lymphatic system D. carbon monoxide, endothelium E. norepinephrine, endothelium
Red imported fire ants are an invasive species in United States. How have they harmed the Texas horned lizard, which feeds on native ants?
a. They act as parasites on the lizards. b. They are poisonous to the lizards. c. They damage the lizard's breeding area. d. They increase the amount of predatory birds, which eat lizards. e. They have replaced many native ant populations, so the lizards have less food.
Which of the following is not a monosaccharide?
a. glucose b. fructose c. deoxyribose d. starch e. ribose
The human body's arterial blood pH is tightly maintained around 7.4 by buffering agents that bind hydrogen ions to stop any change in pH. If an acid-base imbalance overcomes the buffer system, the body changes the ventilation rate, or the rate at which gas enters or leaves the lungs. Changing the ventilation rate changes the concentration of CO2 in the blood, which alters the pH of the blood. In this case, pH 7.4 is the:
A. set point. B. sensor. C. integrator. D. effector. E. homeostatic challenge.