In what types of organisms do plasmodesmata serve as a mechanism of cell-cell communication?
A. protists
B. plants
C. those types of organisms that spend only a
portion of their life cycle in a multicellular
state
D. animals
B
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A deficiency of which essential element leads to intervenal chlorosis?
a. calcium b. potassium c. magnesium d. sulfur
One strain of rII- phage has a deletion in the rII region, another has a point mutation in the rII region. When E. coli K(?) cells are infected with either rII- phage (not both) no plaques form. When E. coli K(?) cells are infected with both rII- phage simultaneously plaques do form. Why do plaques form when E. coli K(?) cells are infected with both types of rII- phage simultaneously?
A) Recombination between the two phage genomes resulted in a wild-type phage. B) The two phage have mutations in different rII genes and their genomes complement each other. C) A protein made by the deletion phage can repair the DNA of the phage with the point mutation. D) Bacteria can survive infection with one phage, but they cannot survive infection with two phages.
Nonspecific defenses against disease include all of the following EXCEPT
A. complement. B. skin and mucous membranes. C. natural killer cells. D. inflammatory reaction. E. antibodies.
Cytopathic effects, such as inclusion bodies and syncytium formation, are the visible signs of viral infections
Indicate whether the statement is true or false