A heartbeat begins in the
A. atrioventricular valve.
B. atrioventricular node.
C. sinoatrial node.
D. right ventricle.
E. left atrium.
C. sinoatrial node.
Biology & Microbiology
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The fluid which bathes and nourishes the tissue cells is the
A. cytoplasm. B. lymph. C. blood. D. interstitial fluid.
Biology & Microbiology
Which bond is weakest?
a. ionic b. double covalent c. polar covalent d. nonpolar covalent e. hydrogen
Biology & Microbiology
Which of these human sex chromosome genotypes is not possible?
A. XXY B. XXXY C. XXX D. YYYY
Biology & Microbiology
The most important factor that determines where major ecosystems are located on the globe is ______ .
a. culture b. environment c. climate d. all of the above
Biology & Microbiology