At which level is biodiversity declining world-wide?
1.genetic diversity within species
2.species diversity
3.ecosystem diversity
4.biodiversity is declining at all levels
4
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High blood pressure in mammals reflexively causes a decrease in heart rate, which results in lowered blood pressure. This is a __________ because ____________
A. negative feedback loop; response to the signal results in a decrease of that signal B. negative feedback loop; response to the signal results in an increase of that signal C. positive feedback loop; response to the signal results in a decrease of that signal D. postive feedback loop; response to the signal results in an increase of that signal E. None of the above are correct.
Cells of the second line of defense called ________ recognize and kill virus-infected cells
A) basophils B) eosinophils C) macrophages D) NK cells E) dendritic cells
Your research project involves the characterization of a recently identified transcription factor. As part of your project, you want to determine if this transcription factor binds directly to any of the general transcription factors. Unfortunately, you are having trouble expressing the full-length protein. What approach may help achieve your research goal?
A. You must find a way to express the full-length protein, since transcription factor functions do not lie in separate domains. B. Express and purify only the DNA-binding domain, and test for binding. C. Identify the RNA that mediates the protein-protein binding. D. Express and purify only the activation domain, and test for binding.
The average mutation rate for DNA replication is 1 mutation for every 10 billion (10,000,000,000 ) nucleotides of DNA replicated. Yet DNA polymerase makes a mistake during replication at an average of 1 in 100,000 nucleotides. What does this say about
DNA replication? A) The base-pairing rules (A pairs with T and G pairs with C) prevent any mutations. B) Cells are extraordinarily proficient at repairing errors made during DNA replication. C) Most errors in DNA replication become mutations. D) Cells recognize that a small fraction of mutations are beneficial to organisms and do not repair those.