Why has finding an effective AIDS vaccine been so difficult?
A. Because it is caused by a virus.
B. Because they have not yet isolated the virus that causes AIDS.
C. Because the virus constantly mutates and so vaccines need to be made for all types.
D. It is a sexually transmitted virus.
E. The body does not make antibodies against the virus.
Answer: C
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Viral neutralization testing is based on the fact that
A. antibodies can be produced against the toxin of a pathogen. B. antibodies have different molecular weights. C. viruses introduced into appropriate cell cultures have a cytopathic effect. D. the gene for a pathogen's antigen can be isolated and introduced into a host cell by way of a plasmid. E. antibodies to certain microbes can be given a fluorescent label.
Nitrogen can be obtained from either organic or inorganic sources.
Answer the following statement true (T) or false (F)
Using the analogy of a 12-hour geologic time clock
a. prokaryotes appear shortly after 5 a.m. b. eukaryotes appear at 9 a.m. c. dinosaurs appear at 10 a.m. d. early fishes appear at 11 a.m. e. the first humans appear at 11:59 a.m.
If a lion eats a gazelle, before the molecules have been broken down by its cells, the lion has gained
What will be an ideal response?