External structures that are found in Archaea but not Bacteria are ________.
A. flagella
B. pili
C. peptidoglycan
D. hami
Answer: D
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The bacterium Thiobacillus secretes sulfuric acid into the environment.
Answer the following statement true (T) or false (F)
The graph below shows a growth curve of E. coli growing in a defined medium containing equal molar amounts of glucose and lactose.
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Based on your knowledge of the regulation of the lac operon, the best explanation of these results is that
A) early on, due to the presence of lactose, the bacteria utilize the lac operon. Glucose is used later.
B) the bacteria are utilizing both sugars simultaneously.
C) the presence of glucose causes the formation of cAMP catabolic repressor protein (CRP) complexes, which shut down the lac operon until the glucose is used up.
D) glucose is used first. Once glucose becomes limiting, intracellular cAMP increases, forming cAMP-CRP complexes that activate the lac operon to use lactose.
E) none of the above
In the nematode C. elegans, ced-9 prevents apoptosis in a normal cell in which of the following ways?
A) It prevents the caspase activity of ced-3 and ced-4. B) Ced-9 remains inactive until it is signaled by ced-3 and other caspases. C) Ced-9 cleaves to produce ced-3 and ced-4. D) Ced-9 prevents blebbing by its action on the cell membrane.
What structural part of a bacterial flagellum is composed of flagellin?
a. Rod b. Basal body c. Hook d. Filament