Why is external water not essential for fertilization in seed plants?
A. Pollen grains are transported by wind or an animal.
B. Sperm cells are used to transport pollen to the archegonia.
C. The sperm cells in seed plants are capable of resisting desiccation.
D. Seed plants use pollen instead of sperm for fertilization.
E. Ovules are contained within the pollen.
Answer: A
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Each of the following is a mechanism for drug resistance transfer between microorganisms, except ________.
A. R-plasmids B. mutation C. conjugation D. transposons
Methanotrophs affect global temperature. This is because:
A. Methanotrophs metabolize methane, thereby reducing the amount of methane in the atmosphere. Since methane is one of the greenhouse gases whose accumulation causes a rise in global temperature, its reduction by methanotrophs helps prevent global warming. B. Methanotrophs convert methane to carbon dioxide and increase the amount of carbon dioxide in the atmosphere. Since carbon dioxide is one of the greenhouse gases whose accumulation causes a rise in global temperature, its production by methanotrophs contributes to global warming. C. Methanotrophs convert carbon dioxide to methane and increase the amount of methane in the atmosphere. Since methane is one of the greenhouse gases whose accumulation causes a rise in global temperature, its production by methanotrophs contributes to global warming. D. Methanotrophs convert methane to carbon dioxide, thereby decreasing the amount of methane in the environment but increasing the amount of carbon dioxide there. Since both methane and carbon dioxide are greenhouse gases whose accumulation causes a rise in global temperature, the decrease in one cancels the increase in the other and methanotrophs have no net effect on global warming. E. Methanotrophs combine carbon dioxide and methane to form petroleum and in this way take both methane and carbon dioxide out of the atmosphere. Since both methane and carbon dioxide are greenhouse gases whose accumulation causes a rise in global temperature, the decrease in both helps prevent global warming.
What percentage of the immigrants into your experimental populations have the A allele?
a. 50% b. 5% c. 0.5%
As described in "A Note About Bacterial Reproduction -- and the "Culture Bias,"" the organism Epulopiscium does not divide by binary fission. Rather, each cell increases in size and divides to produce multiple daughter cells that are held within the original cell well. After lysis, those daughters are released to repeat the process. Assuming Epulopiscium could be grown in pure culture in the laboratory in broth and on solid media (it currently cannot), which method would be best for measuring the increase in biomass during growth?
A. Direct microscopic count; the experimenter can directly count the number of cells and extrapolate to the biomass. B. Turbidity readings from a spectrophotometer; the increase in biomass will directly vary with the turbidity of the culture. C. Chemostat growth; it will prevent the culture from entering the death phase. D. The viable plate count; each colony derives from a single cell and the number of colonies equals the number of cells.