How are bacteria the beginning and end of the nitrogen cycle? What will be an ideal response?
Bacteria are responsible for nitrogen fixation that is converting N2 in the atmosphere to NH4+ in the
soil. This is how nitrogen enters the biological cycle. At the other end, bacteria are responsible for
denitrification: converting NO3- back to N2. This removes nitrogen from biological access.
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In the experiments conducted by Avery, McCarty, and MacLeod, which one of the following hypothetical results would indicate that protein, not nucleic acid, was Griffith's transforming principle?
A. None of the extracts from heat-killed cells are able to transform nonvirulent bacteria. B. All of the extracts from heat-killed cells are able to transform nonvirulent bacteria. C. Only the extract from heat-killed cells treated with RNase are unable to transform nonvirulent bacteria. D. Only the extracts from heat-killed cells treated with DNAse are unable to transform nonvirulent bacteria. E. Only the extracts from heat-killed cells treated with protease are unable to transform nonvirulent bacteria.
In tissue capillaries, __________ combines with water to form carbonic acid, which after being transported to the lungs, dissociates back to its constituents.
A. CO2 B. O2 C. H2CO3 D. hemoglobin E. HCO3-
The stomach is involved in four of the following. Which one is NOT a function of the stomach?
a. It begins carbohydrate digestion. b. It mixes food. c. It stores food. d. It begins protein digestion. e. It regulates passage of food into small intestines.
All human cells carry
a. one X and one Y chromosome b. at least one X chromosome c. at least one Y chromosome d. a pair of X chromosomes