The crown of the tooth is covered by _____, the hardest substance in the human body
a. enamel
b. calcium
c. bone
d. dentin
a
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The vertebrate spinal cord develops from the embryonic _____
A) notochord B) dorsal hollow nerve cord C) pharyngeal pouch D) coelom E) podia
An antibiotic that increased the activity of ________ would likely result in cell death
A) autolysin B) binary fission C) stationary growth D) ionic bonds in proteins
Which of the following statements about plant embryo development is correct?
A. The suspensor forms from the shoot apical meristem before development of the root apical meristem. B. The development of the shoot and root apical meristems is controlled independently. C. The plant hormone abscisic acid is important in the development of the shoot-root axis. D. The protoderm establishes the procambium tissue in the young plant embryo.
In an EKG, what does the QRS wave indicate?
A) first heart sound B) electrical signal over the atria C) second heart sound D) electrical signal over the ventricles