When using the Nernst equation to calculate membrane potential, we are making several assumptions about conditions in the cell. Which of the following is not a good assumption?
(a) The temperature is 37°C.
(b) The plasma membrane is primarily permeable to Na+.
(c) At rest, the interior of the cell is more negatively charged than the exterior.
(d) K+ is the principal positive ion in the cell.
(b) The cell has K+ leak channels. At rest, the cell is mostly permeable to K+ because of the presence of these channels.
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Plastic marine debris was collected from multiple sites in the ocean and examined with electron microscopy and next-generation sequencing. These techniques revealed microbial communities growing on the plastics. Which of the following statements is correct regarding these communities?
A. These communities are very likely to be pure cultures, as plastics have been synthesized precisely because they are resistant to microbial degradation. B. There are no bacteriophage that use these microbes as hosts, as viruses are rare in marine ecosystems. C. The community within the plastic must be very similar to the community in the surrounding ocean waters. D. At least one member of the community must synthesize an enzyme to degrade the hydrocarbon comprising the plastic.
The first federally approved gene therapy test on humans was designed to treat
a. severe combined immune deficiency. b. diabetes. c. cystic fibrosis. d. hemophilia. e. leukemia.
The ancestors of modern ________ performed the oxygenic photosynthesis responsible for converting our anoxic planet to an oxygenated one.
A. Firmicutes B. Cyanobacteria C. Crenarchaeota D. Proteobacteria
When gametes fuse during fertilization, a(n) ________ is produced
A) haploid individual B) zygote C) sperm D) egg