Which of the following best defines a strain in microbiological terms?
A) a pure culture that is not totally identical to other cultures of the same species
B) a group of organisms with a limited geographical distribution
C) a mixed population of cells,genetically distinct, but with highly similar phenotypic characteristics
D) groups of cells all derived from and identical to a single parent species
E) same as a species
A
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Many songbirds breed in North America in the spring and summer and then migrate to Central and South America in the fall. They spend the winter in these warmer areas, where they feed and prepare for the spring migration north and another breeding season
Two hypothetical species of sparrow, A and B, overwinter together in mixed flocks in Costa Rica. In spring, species A goes to the east coast of North America, and species B goes to the west coast. What can you say about the isolating mechanisms of these two species? A) They must have strong postzygotic isolating mechanisms to spend winter in such close proximity. B) They must have strong prezygotic isolating mechanisms to spend winter in such close proximity. C) Their winter habitat has no bearing on their degree of reproductive isolation. D) Reinforcement must be occurring when they winter together.
In which of the following vessels or chambers is blood relatively high in oxygen?
a. pulmonary artery b. right atrium c. inferior vena cava d. right ventricle e. pulmonary vein
Initial characterization of streptococcal species is based on __________.
A) bile esculin hydrolysis B) the type of hemolysis exhibited C) CAMP reaction D) bacitracin sensitivity
Because of its function, this hormone is often called interstitial cell-stimulating hormone
A) LH B) inhibin C) FSH D) GnRH