Before photosynthesis evolved, ________ was rare in Earth's atmosphere
A) O2 B) CO2 C) H2O D) N2 E) air
A
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Gene expression is the same in both prokaryotes and eukaryotes; they are just regulated differently. What is gene expression?
a. discontinuation of the production of a gene due to an excess of the product b. a form of positive feedback where the product induces additional production of a protein c. the process of turning on a gene to produce RNA and protein d. a form of remote sensing similar to chemotaxis
In a survey of Dall mountain sheep in Denali National Park in Alaska, researchers found that wolves preyed primarily on the most vulnerable members of the population, the young and the old. What conclusion is best supported by this data?
A. Dall mountain sheep in Denali are an r-selected population. B. A program should be established to cull the wolf population. C. A program should be established to cull the sheep population. D. Wolf predation is not dramatically reducing the sheep population. E. The wolf population is at its carrying capacity, so it is no threat to the sheep population.
Freshwater fish reside in hypotonic environments. They do not drink water, and they excrete large volumes of hypotonic urine in an effort to osmoregulate. How do they obtain an adequate supply of electrolytes?
A) The rectal gland is specialized to produce the dilute (hypotonic) urine and conserve ions. B) Chloride cells transport additional electrolytes into the circulation of these organisms. C) Gill filaments take up additional electrolytes from freshwater. D) There is an increase in Na+/K+-ATPase activity across the basolateral membrane.
When a DNA promoter sequence is methylated, ____
a. it is permanently silenced because the methyl group can never be removed b. it is temporarily silenced because the methyl group can be removed c. it is perpetually transcribed because the methyl group can never be removed d. it is temporarily transcribed because the methyl group can be removed e. the impact on expression depends on the gene being controlled by the promoter