Explain the advantages of using recombinant DNA technology to produce human proteins in transgenic plants,
animals, or cultured cells. What will be an ideal response?
ANSWER: Before the development of biotechnology, therapeutic proteins such as insulin, growth hormone, and
blood-clotting factors were isolated from many sources, including animals in slaughterhouses, donated
human blood, and even human cadavers. In some cases, contamination from these sources exposed
people to serious and potentially fatal risks. For example, in the early 1980s, donated blood was not
tested for HIV, and as a result, about 60% of all hemophiliacs became infected with HIV from
contaminated clotting factor prepared from pooled blood donations. Hemophiliacs who received the
serum-concentrated clotting factor also faced a risk of hepatitis infection.
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E. coli has been isolated and cultured from three different individuals. Upon biochemical testing of these three cultures, you find that there are differences in some reactions. What is the best explanation of these differences?
A. These represent three different species of E. coli. B. This is normal genetic variation seen among strains of E. coli. C. The other two cultures are not really E. coli. D. Mistakes have been made in the test interpretation. E. Two of the cultures are mutants of the other.
Consider the 4.6-billion-year history of the Earth. Geological and fossil evidence indicates that during the greatest fraction of its history, the Earth
a. was too hot to have either a solid surface or any form of life. b. had organic molecules in liquid water, but no living forms. c. had unicellular organisms, but not multicellular. d. had both multicellular and unicellular organisms, but no terrestrial (land) forms. e. had both terrestrial, freshwater, and marine organisms, both unicellular and multicellular.
Which statement is NOT true?
a. Carbon dioxide is more soluble in fluid than in oxygen. b. Carbon dioxide diffuses more rapidly across the respiratory surface than oxygen does. c. The major muscle involved in breathing is the diaphragm. d. Oxygen is carried primarily by blood plasma. e. Carbon dioxide is carried by the blood plasma.
If phospholipids form a spherical structure when placed in water, then which of the following is the
most logical conclusion about those phosopholipid molecules? a. They are not amphipathic. b. They contain two fatty acid chains. c. They are cone-shaped. d. They form a bilayer. e. Both their ends are hydrophilic