Chan-Seung Lee
Joined: 03 Dec 2005
Posts: 1032
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 Posted: Sat Nov 02, 2013 9:17 pm Post subject: what does it mean? |
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| Such speculation, however fascinating, begs the main question. How does DNA have any sense of time? It lives in a purely chemical world, surrounded by molecules that float by. It is certainly true that every cell maintains incredibly complex sequencing of chemical reactions—the marvel is that a cell can breathe, feed itself, excrete wastes, divide, and heal while living on death row, since a sentence of death is hanging over each cell all the time. This sentence is imposed by the fact that a cell cannot store reserves of oxygen and nutrients. It depends entirely on what flows into it. Cells stand at the forefront of life, storing no more than three seconds' worth of food and air; they cannot wait on late deliveries; lapses in efficiency would be instantly fatal. |
1. What does 'stand' in the quote mean?
2. What does 'three seconds' worth of food and air' mean?
(Why the writer used the word 'three' ?)
Thanks. |
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