Which of the following causes the rapid change of membrane polarity during an action potential?
(A) Diffusion of neurotransmitters such as acetylcholine
(B) Diffusion of positively charged ions across the cell membrane
(C) Release of electrons from inside the cell
(D) Release of protons from inside the cell
Answer: (B) Diffusion of positively charged ions across the cell membrane
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You are a forensic technician working on a DNA sample obtained from a crime scene. Your job is to compare the unknown DNA sample with known DNA samples collected from five different suspects. Preliminary analysis using only a few DNA markers revealed that the unknown sample could possibly match two of the suspects. After consulting the case file, you find out that these two suspects are brothers (but not twins). You realize that you will have to do a more detailed analysis on the samples so that you can distinguish between the brothers and determine which brothers' DNA matches the unknown sample.Why can't you use mitochondrial DNA to distinguish between these two suspects?
A. The brothers share the same mitochondrial DNA. B. The sequence of mitochondrial DNA has not yet been determined. C. Because mitochondrial DNA is inherited in a paternal pattern. D. There are no molecular techniques available that allow one to analyze mitochondrial DNA.
Careful, long-term studies conducted by Steve Hubbell and colleagues __________ for the proposal that spatial and temporal variation in gap formation caused by disturbance explains high diversity of tropical trees.
A) provide support B) fail to provide support
A rise in sodium levels and extracellular volume leads to a rise in blood pressure. As a result, ____.
A. renin levels rise, but aldosterone levels fall B. renin levels fall, but angiotensin levels rise C. renin and aldosterone levels rise D. renin and aldosterone levels drop E. renin levels drop, but aldosterone levels remain the same
Which of these relationships is not based on survival?