Nitrogen is released into the atmosphere by ____
a. nitrogen fixation
b. denitrification
c. nitrification
d. ammonification
e. decomposition
ANSWER: b
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Which of the following comparisons between the moss life cycle and fern life cycle is NOT valid?
A. Both kinds of plants have flagellated sperm that need water to reach the female gamete. B. The sporophyte generation is much larger than the gametophyte generation in ferns but is smaller than the gametophyte generation in mosses. C. The spores are produced in capsules on stalks in mosses but in small structure called sori on the underside of leaves in ferns. D. Both kinds of plants depend on wind for dispersal of spores. E. The gametes are produced in gametangia in mosses but on the underside of leaves in ferns.
To study the fine structure of a mitochondrion, which type of microscope is least appropriate?
a. light b. scanning electron c. transmission electron
Cartilage is different from bone because cartilage:a
is rich in nerves. b. contains veins. c. has a matrix that is composed almost exclusively of collagen. d. contains lymphatic vessels. e. contains arteries.
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.