Scientists measured the pressure in the xylem of redwood trees at different heights and found that the higher they made their measurements, the lower the pressure. They extrapolated this to a pressure of zero, and concluded that the tallest a tree could grow is 122–130 meters. The tallest known tree on Earth is 112.7 meters. What assumption were the scientists making to conclude that when pressure was zero, the plant could grow no further?
A. Turgor pressure would be greater than gravity.
B. Transpiration would be less than uptake of water from the xylem.
C. Leaves above that point would not receive any sunlight.
D. Leaves above that point would not receive any water.
E. Stems above that point could not transport sugars in their xylem.
D. Leaves above that point would not receive any water.
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In ________, people with a serious genetic disorder are not permitted to have children.
A) the United States B) England C) China D) Russia
Denitrification ____
a. converts ammonium to nitrates b. reduces nitrates to nitrites c. reduces ammonia to ammonium d. converts atmospheric nitrogen to ammonia e. converts nitrates to nitrogen gas
Which is NOT a benefit of the understanding of evolution to understanding the field of biology?
A) Understanding evolution helps us to understand molecules. B) Understanding evolution helps us to analyze ecosystems. C) Understanding evolution helps advance biotechnology and medicine. D) Understanding evolution helps us to understand why stars and galaxies change over time.
Imagine that it is 1965 and the bacterium Thermus aquaticus has not yet been discovered. As a geneticist interested in forensics applications, you are attempting to develop a gene-amplifying technique similar to PCR
In a test tube, you place a DNA sample, free nucleotides, human DNA polymerase, and the appropriate primers for the DNA sequence being analyzed. You first heat the sample to 90°C, then cool it to 50°C, and then reheat it to 70°C. Based on this scenario and your knowledge of how modern PCR works, the result of these procedures will be A) unsuccessful, because the enzyme will denature during the second step (cooling). B) unsuccessful, because the enzyme will denature during the first step (heating). C) unsuccessful, because the enzyme will denature during the third step (reheating). D) unsuccessful, because human DNA polymerase cannot recognize the primers used. E) successful copying of the DNA, because it follows modern PCR procedures almost perfectly.