Explain how an oligotrophic lake can become eutrophic
What will be an ideal response?
ANSWER: An oligotrophic lake is poor in nutrients and organic matter; eutrophic lakes are rich in
nutrients and organic matter. Over long periods of time, as sediments and nutrients
accumulate, lakes naturally change from oligotrophic to eutrophic. The decomposition of
organic matter in eutrophic lakes depletes oxygen in the hypolimnion and high productivity
in the epilimnion often chokes the water with seasonal blooms of cyanobacteria and
filamentous algae.
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Manufacturers make vegetable oils solid or semisolid at room temperature by _____.
A. adding hydrogen atoms to the double bonds in the fatty acid hydrocarbon chains B. removing hydrogen atoms and forming additional double bonds in the fatty acid hydrocarbon chains C. removing hydrogen atoms and forming additional single bonds in the fatty acid hydrocarbon chains D. adding hydrogen atoms to the single bonds of the fatty acid hydrocarbon chains E. none of the above
Which one of the following is the organ of the inner ear that contains hair cells which convert fluid pressure waves to nerve impulses?
A. vestibular System B. semicircular canals C. organ of Corti D. statolith
Which of the following is not endothermic?
A. turkey B. fish C. rabbits D. mice E. pigeon
Which of the following statements about transcriptional regulation is incorrect?
A. Regulatory transcription factors are proteins that bind to enhancer DNA sequences and then recruit one or more general transcription factors. B. A typical gene contains only one enhancer sequence. C. General transcription factors are required to initiate the process of transcription. D. General transcription factors bind to the TATA box in the promoter region of a gene. E. RNA polymerase components are recruited to the promoter region by the general transcription factors bound to the TATA box.