One atom of sodium has a mass number of 22 units; another atom of sodium is 23 units. These two atoms are 

A. nonreactive.
B. unstable.
C. ions.
D. isotopes.


D. isotopes.

Biology & Microbiology

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Lysogeny is essential for the virulence of many pathogenic bacterial strains

Indicate whether the statement is true or false.

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Which PCR step causes the denaturation of double-stranded DNA?

A. Add primers. B. Heat target DNA to 94°C. C. Add DNA polymerase and nucleotides at 72°C. D. Repeat the cycle of heating and cooling. E. Cool DNA to between 50°C and 65°C.

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The first detailed and quantitative studies on inheritance were carried out by an Austrian monk named ________.

A. Darwin B. Mendel C. Mendeleev D. Benedict

Biology & Microbiology

Kingdom Protista includes

A) archaea & monera. B) kelp & fungi. C) parasitic worms. D) algae & protozoans.

Biology & Microbiology