Considering alligators and birds, which of the
following is a derived character?
a. four-chambered heart
b. feathers
c. four limbs
d. a bony skeleton
e. egg laying
A
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The equalization of pressures between the ear and throat is made possible by the
a. pharynx. b. Eustachian tube. c. cupula. d. semicircular canals. e. round window.
While synthesizing a new blue pigment, a chemist notices that the new compound accumulates between an aqueous (water) environment and a hydrophobic environment
When added to a mixture of oil and water, the pigment creates a blue ring around the droplets of oil. Which of the following statements best describes this new pigment? A) The pigment is a polar molecule and is forming hydrogen bonds with both the water and oil molecules. B) The pigment is hydrophilic and will not form hydrophobic bonds with the oil. C) The pigment is amphipathic, having polar and nonpolar regions. D) The pigment is neither polar nor nonpolar; it is apolar. E) The pigment is probably hydrophobic and is attempting to bond with the oil.
Of the 20 standard amino acids, only ___________ is not optically active. The reason is that its side chain ___________.
A) alanine; is a simple methyl group B) glycine; is a hydrogen atom C) glycine; is unbranched D) lysine; contains only nitrogen E) proline; forms a covalent bond with the amino group
Viroids are of economic significance because they cause disease in ________.
A. animals B. plants C. humans D. All of the choices are correct.