Which structure prevents blood flowing back into the atria during ventricular contractions?
A. foramen ovale
B. semilunar valves
C. atrioventricular valves
D. carotid blood shunts
E. sinoatrial node
Answer: C
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a. nephridia b. contractile vacuoles c. Malpighian tubules d. pharynx e. flame cells
Vertebrates" refers to animals that possess ____
a. hair b. mammary glands c. the ability to give birth to live young d. a backbone e. lungs
The shape of the beaks of Darwin's finches and industrial melanism are often cited as examples of the process of ________ leading to evolutionary change.
A. natural selection B. coevolution C. intelligent design D. artificial selection E. founder effect
All of the following are correct about the autoclave, except
A. the duration of the process depends on how full the chamber is. B. it is the temperature that kills the microbes, not the pressure by itself. C. it is important not to overload the chamber. D. it is effective for sterilizing powders, oils, and waxy substances. E. sterilization is achieved when steam condenses against the objects in the chamber and raises their temperatures.