Primary productivity is affected by the availability of:
A. sunlight.
B. water.
C. nutrients.
D. sunlight and nutrients.
E. sunlight, water, and nutrients.
E
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Based on the theory of endosymbiosis, which of the following would you expect to find in a chloroplast?
A. DNA B. cellulose C. a mitochondrion D. silica E. a nucleus
A major difference between allopatric and sympatric speciation is whether
A. resulting species are reproductively isolated or not. B. gene flow continues to occur or not. C. two or three species result. D. geographic isolation is required or not. E. the new species are separated by a prezygotic or postzygotic isolating mechanism.
How are hormone levels regulated?
A. An endocrine gland can respond to the blood level of the hormone it produces. B. A product can trigger hormone production; the hormone can then reduce the amount of product which in turn reduces the level of hormone. C. A hormone can trigger a second gland to secrete a hormone that dampens production of the first hormone. D. A second contrary hormone can counteract the effect of the first hormone. E. All of the choices are correct.
Cell biologists employ targeted fluorescent dyes or modified fluorescent proteins in both standard fluorescence microscopy and confocal microscopy to observe specific details in the cell
Even though fluorescence permits better visualization, the resolving power is essentially the same as that of a standard light microscope because the resolving power of a microscope is limited by the __________ of light. (a) absorption (b) intensity (c) filtering (d) wavelength