Considering the structure of double-stranded DNA, which kind(s) of bonds hold one complementary strand to the other?
A) van der Waals
B) ionic
C) disulfide
D) hydrogen
E) covalent
Answer: D
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The mode of infection for which of the following organisms is the ingestion of cysticercoid in an infected arthropod or by the direct ingestion of the egg? Autoinfection may also occur
a. D. latum b. Hymenolepis nana c. Taenia saginata d. Taenia solium
You want to examine the structure of the protein coat of a virus by microscopy. Which microscope is your best choice, and why?
A. The scanning electron microscope-it has excellent resolution and magnification, much higher than a light microscope, and can clearly visualize viruses. B. An atomic force microscope-this has the highest resolution and magnification of the microscopes we discussed. Here, we want to visualize a subcomponent of the virus particles, so we need the best value for resolution and magnification we can possibly achieve. C. A fluorescent microscope-this will let us tag the protein coat with colored dyes in order to visualize it using this light microscope at 1000x. D. A bright-field light microscope-of course, we'll need to stain the viruses before we can visualize them against the bright white background at 1000x total magnification.
In a __________, water or some nutrient moves from an environmental reservoir, through organisms,
then back to the environment. Fill in the blank(s) with the appropriate word(s).
A plant embryo enclosed in a protective covering is a(n)
A. pollen. B. egg. C. seed. D. spore.