In the disease myasthenia gravis, there is a deficiency of acetylcholine receptors at the neuromuscular junction. This blocks contraction by preventing muscle activation at which point?
A. generation of action potentials in the motor neuron
B. opening of the T-tubule system
C. release of Ca2+ from the sarcoplasmic reticulum
D. altering the interaction of troponin with tropomyosin
E. generation of action potentials in the muscle fiber
E. generation of action potentials in the muscle fiber
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In influenza virus, antigenic shift
A. results from reassortment of genomes when two different strains of flu viruses infect the same cell. B. can result in major epidemics or pandemics. C. results from the accumulation of mutations in HA and NA in a single strain of flu virus. D. results from reassortment of genomes when two different strains of flu viruses infect the same cell and can result in major epidemics or pandemics.
The mechanism of muscle contraction was first studied in ____ muscle using high-resolution ____ microscopy
a. skeletal; light b. smooth; light c. skeletal; electron d. smooth; electron e. cardiac; electron
Which of the following is not a standard therapy for cancer treatment?
A. surgery B. radiation therapy C. chemotherapy D. immunotherapy E. all of these are standard therapies for the treatment of cancer
Why does Dallas, Texas, have a higher yearly average temperature than Chicago, Illinois?
A) Dallas is at a higher latitude than Chicago. B) Chicago experiences more prevailing westerly winds than Dallas. C) Dallas receives more solar irradiance than Chicago. D) Dallas is closer to a large body of water, than is Chicago.