Which statement is accurate if the first true cell arose by the RNA-first hypothesis?
A. Proteins in the protocell would have evolved the ability to synthesize DNA.
B. The first cell had RNA genes that could have specified protein synthesis.
C. RNA genes replicated because of the presence of proteins.
D. All of these statements support the RNA-first hypothesis.
E. None of these statements support the RNA-first hypothesis.
Answer: B
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Which of the following statements about bulk transport is false?
A. Bulk transport is found in simple multicellular organisms, but not unicellular organisms. B. Bulk transport involves the active transport of molecules throughout an organism's body. C. Bulk transport allows for materials to be moved over greater distances than is possible with diffusion. D. Bulk transport moves materials at faster rates than is possible with diffusion. E. Bulk transport allows for animals and plants to grow very large.
The range of the grizzly bear in the 48 contiguous United States is now less than 1% of what it was in 1800. What has been proposed to help maintain genetic variation in the remaining populations of this species?
A. protected corridors between all of the remaining populations B. regular exchange of bears between isolated populations C. proserving more small patches of forest D. cloning of the most genetically diverse remaining females E. establishment of new parks in Colorado and New Mexico
Which of the following generally causes stomata to open?
a. release of abscisic acid by the roots b. a drop in CO2 concentration in leaf air spaces c. exposure to red light d. a drop in O2 concentration in leaf air spaces e. an increase in CO2 concentration in the leaf air spaces
At night, faint objects are best seen when not looked at directly. What is the basis of this phenomenon?
A. Cone photoreceptors are most sensitive in dim light, and few cones are present in the fovea. B. Cis-retinal builds up in the fovea at night and is degraded during the day. C. Rod photoreceptors are most sensitive in dim light, and few rods are present in the fovea. D. Rhodopsin is transported away from the fovea at night.