Mediated transport of polar molecules and ions across the plasma membrane utilizes a(n) ________ carrier that binds to the substance and causes a conformational change to allow its movement across the membrane.
A. enzyme
B. porin
C. lipid
D. protein
Answer: D
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When grouping organisms, which classification is most specific for a particular type of organism?
A. Kingdom B. Phylum C. Order D. Family E. Species
The snipping out of specific introns is an example of
what type of gene expression control? a. transcriptional b. transcript processing c. transcript transport d. translational e. post translational
The level of carbon dioxide in the blood is monitored by nerve tissue. If you exercise strenuously, the increase in cellular respiration consumes oxygen from the blood and produces surplus carbon dioxide removed in the blood. Since this physical exertion requires faster breathing to replenish oxygen supplies and carry away carbon dioxide, the carbon dioxide sensors result in signals from the brain to increase breathing rate. After you have rested, and carbon dioxide levels are back to normal, your breathing rate decreases too. This is an example of
A. a positive feedback loop that stimulates a response opposite to the stimulus. B. a response to a sensory impulse that causes a muscle or gland to react. C. the dynamic interplay between events that tend to change the internal environment and events that tend to keep it the same. D. a negative feedback loop that stimulates a response similar to the stimulus. E. the dynamic interplay between events that tend to change the internal environment and events that tend to increase the changes.
What are believed to be the evolutionary ancestors of mitochondria?
a. ancient Archaea b. ancient proteobacteria c. ancient green bacteria d. ancient cyanobacteria