Why is back pain so common in humans? What will be an ideal response?
ANSWER: Unlike the vast majority of other vertebrates, humans are upright walkers. As a result, the
intervertebral disks which were intended primarily to allow flexibility between the vertebrae
have now become weight-bearing structures. They are often not up to the task and more or
rupture. This can result in an impingement on the nerves of the spinal cord and chronic pain.
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Carbon and hydrogen have similar electronegativities and combine together to form hydrocarbon molecules. What type of bonds form between these atoms?
A. hydrogen. B. ionic. C. polar covalent. D. nonpolar covalent. E. electrostatic.
As early as the 1940s, researchers knew that bacteria could be grown in a minimal medium. In this
minimal medium the most common source of organic carbon is:
a. peptidase. b. glucose. c. rubisco. d. catalase. e. ammonium chloride.
A population of T cells was stimulated to proliferate in response to a particular antigen. A sample of 1000 stimulated cells was analyzed by fluorescence-activated cell sorting (FACS) for total DNA content
Of the 1000 cells, 400 had a 2n amount of DNA, 200 had a 4n amount of DNA, and the remaining 400 cells had between a 2n and 4n amount of DNA. Additional immunofluorescence analysis revealed that 200 of the cells were in various stages of M phase and that M phase lasted 2 hours. What is the total length of the cell cycle? A) 8 hours B) 12 hours C) 18 hours D) 20 hours E) 24 hours
The Holocene epoch marks the appearance of:
a. humans. b. reptiles. c. amphibians. d. large mammals. e. marine vertebrates.