One way to study a microbial ecosystem is to isolate microorganisms from it and study their properties in laboratory culture
Indicate whether the statement is true or false.
Answer: TRUE
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Immediately after an action potential passes along an axon, it is not possible to generate a second action potential. Thus, we state that the membrane is briefly _____
A) hyperexcitable B) refractory C) fully depolarized D) above threshold E) at the equilibrium potential
Which is incorrect about histoplasmosis?
A. It is transmitted by inhalation of spores. B. It never spreads to sites outside the respiratory tract. C. Chronic cases have symptoms similar to tuberculosis. D. It causes respiratory infections that range from mild to severe. E. The pathogen grows inside macrophages.
The bitter receptor hTAS2R38 is activated by glucosinolates found in plants such as turnips and broccoli. Glucosinolates can block synthesis and transport of iodine. Before the advent of iodized salt, this was a particular problem in areas of the world that are naturally low in iodine. Why might the human population include different variants of the hTAS2R38 gene?
A. Areas of high iodine are generally coastal, and turnips and broccoli are not easily grown there. B. Iodine created mutations in the hTAS2R38 gene. C. Where iodine was low, eating plants rich in glucosinolates helped people metabolize iodine, but where iodine was high they avoided such foods. D. Where iodine was low, it was important to avoid foods with glucosinolates, but where iodine was plentiful, palatability of a wider range of plants was beneficial. Clarify Question What is the key concept addressed by the question? What type of thinking is required? Gather Content What do you already know about taste receptors? What other information is related to the question? Choose Answer Given what you now know, what information is most likely to produce the correct answer? Reflect on Process Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
Scientists can determine the size of DNA fragments through a process known as gel electrophoresis. In this process, DNA is loaded into a gel submerged in a liquid buffer through which an electric current is run. Large DNA molecules move slower and can be observed at the top of the gel, whereas smaller DNA fragments move faster (and are seen at the bottom of the gel). Based on what you know about the properties of DNA, how is the electric current arranged in this process?
a. Since DNA is negatively charged, the positive end is placed at the top of the gel, and the negative end is placed at the bottom of the gel. b. Since DNA is negatively charged, the negative end is placed at the top of the gel, and the positive end is placed at the bottom of the gel. c. Since DNA is positively charged, the negative end is placed at the top of the gel, and the positive end is placed at the bottom of the gel. d. Since DNA is positively charged, the positive end is placed at the top of the gel, and the negative end is placed at the bottom of the gel. e. Since DNA is uncharged, the placement of the positive end and negative end does not matter.