Which of the following structures is the smallest?
A) DNA molecule
B) chloroplast
C) mitochondrion
D) lipid bilayer
Ans: A) DNA molecule
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In one experiment, mice were genetically engineered to overexpress a particular set of miRNAs. These animals developed lymphomas. The genes encoding these miRNAs were acting as _________.
a) tumor suppressors b) sex-linked dominant alleles c) holandric genes d) oncogenes
Suppose that plasma membranes were single layers of phospholipids rather than double layers, and the heads faced the extracellular fluid. The interior of this hypothetical cell would have to be
A) nonpolar only. B) hydrophilic only. C) polar only. D) hydrophobic only. E) hydrophobic and nonpolar.
Chagas disease is a human parasitic disease, spread by the reduviid bug. This disease results in thousands of deaths yearly. Thinking about what you know about how this disease is spread, do you feel we are likely to start seeing cases of Chagas disease in the Northern United States?
A) Yes, because of the increased travel done by humans, this disease could be spread B) No, because of the geographical limitation of the vector
The greenhouse effect is
A) of little concern, since it is part of the normal cycle for the planet. B) reduced by photosynthesis, which removes carbon dioxide from the atmosphere. C) reduced by the addition of carbon dioxide to the atmosphere, since carbon dioxide removes excess heat from the Earth's surface and reflects it back into space. D) made worse by photosynthesis, which adds carbon dioxide to the atmosphere. E) reduced by the burning of fossil fuels, which removes oxygen from the atmosphere.