A catalase test was performed from a sheep blood agar plate on a colony of streptococci, and bubbling was observed. Which of the following statements explains this discrepancy?
a. Catalase is the inappropriate test to use on colonies of streptococci; therefore the re-sults are invalid.
b. The colony may have been contaminated with sheep red blood cells, causing a false-positive result.
c. The colony was most likely enterococci, not streptococci.
d. No discrepancy is present. Streptococcus is a catalase-positive colony.
B
Sheep red blood cells produce catalase; therefore, if some of the media was incorporated into the colony, a false-positive result would occur, because streptococci are catalase-negative colonies.
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A variety of finch species within the Hawaiian Islands have acquired different types of beaks needed for utilizing specific food resources. The process by which these different species of finches came about is likely to have involved
A. natural selection. B. evolution. C. an accumulation of harmful genetic mutations. D. both natural selection and evolution. E. None of these choices are correct.
The body pattern of plants
A. is determined by the orientation of the first zygotic cell division. B. is determined by sunlight. C. is determined by three axes. D. develops in segments.
What is a difference between the structure of DNA and proteins?
A) DNA is composed of amino acids and proteins are composed of nucleotides. B) DNA is composed of the four nucleotides A, G, C, and T and proteins are composed of the four nucleotides A, G, C, and U. C) DNA is composed of nucleotides and proteins are composed of amino acids. D) DNA is composed of 10 different amino acids and proteins are composed of 20 different amino acids.
In many parts of the Amazon Basin, farmers have cut down the tropical rain-forest trees and planted crops. However, the farmers often abandon these croplands after a few years and move on. What are some possible reasons for this?
What will be an ideal response?