The ability of some microbes, such as Trypanosoma or Giardia to alter their surface molecules and evade destruction by the host's antibodies is called
A) antigenic variation.
B) lysogenic conversion.
C) virulence.
D) cytopathic effect.
E) cytocidal effect.
A
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Imagine that you are on a nature walk. Your guide points out a lichen growing on a tree trunk, and comments that lichens are actually a type of fungi. You know that this description is not correct. Why?
A. Lichens are actually vascular plants that produce hyphae instead of roots. B. Lichens are actually composed of both fungi and green algae (or cyanobacteria). C. Lichens are actually composed of both fungi and bryophytes. D. Lichens are actually bryophytes that produce hyphae instead of roots.
Which letter indicates the direction of incoming light in a typical vertebrate?
Vision differs from the other senses in two interesting ways. Although most sensory receptor neurons are depolarized when the receive a stimulus, rod and cone cells become hyperpolarized when they receive light. When hyperpolarized, they stop releasing inhibitory neurotransmitter and allow the bipolar cells to fire. A second unusual aspect is that the vision circuit seems to be organized "backwards" -- the light must pass through the layers of ganglion and bipolar cells to reach the rods and cones.
A. A
B. B
C. C
D. D
E. All of the directions are possible.
Craving alcohol and an inability to limit the amount of alcohol one consumes are symptoms of fetal alcohol syndrome.
Indicate whether the statement is true or false
Which hormone establishes and maintains normal metabolism?
a. epinephrine b. aldosterone c. oxytocin d. PTH
e. thyroid hormone