Which of the following statements is TRUE of restriction enzymes?
A. They are not naturally produced by bacteria, but are bioengineered by them.
B. They protect bacterial cells from invasion by foreign DNA.
C. There are less than 10 restriction enzymes known.
D. They cleave the DNA backbone at only one location.
E. They cleave DNA only at sites of adjacent thymine bases.
B. They protect bacterial cells from invasion by foreign DNA.
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Climate scientists are developing methane hydrates to decrease the effects of global warming
Indicate whether the statement is true or false.
Which of the following statements about chytrids and basidiomycetes is incorrect?
A. Chytrids have a well-developed mycelium, whereas basidiomycetes have a welldeveloped fruiting body. B. Chytrids are aquatic, whereas basidiomycetes are terrestrial. C. Chytrids have flagellated spores, whereas basidiomycetes do not. D. Chytrids lack well-defined hyphae, whereas basidiomycetes have well-defined hyphae. E. Chytrids lack a heterokaryotic phase, whereas basidomycetes have a heterokaryotic phase.
Which of the following is characteristic of cones?
a. night vision b. dim light c. perception of color d. coarse perception of movements e. found in optic disc
Characteristics of chancroid include:
A. sexually transmitted B. occurs mostly in the tropics and subtropics C. lesion develops at portal of entry D. bubolike swelling of the lymph nodes E. All of the choices are correct.