The bacterial A-B toxins often consist of a two-chain molecule. The 'A chain' attaches the bacterium to the cells, and the 'B chain' has biological activity against some vital function of the cells

a. true
b. false


Ans: b. false

Biology & Microbiology

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How many skeletal muscles are found in the

body?

a. 900 b. 800 c. 350 d. 700 e. 70

Biology & Microbiology

When you inhale, the diaphragm moves ___

and the intercostal muscles move the rib cage ___.

a. downward...outward b. outward...downward c. outward...outward d. downward...downward e. outward...upward

Biology & Microbiology

Endonucleases and exonucleases are enzymes that can remove nucleotides from a polynucleotide chain. An endonuclease removes nucleotides ________ while an exonuclease removes nucleotides ________.

A. from the ends of the chain; internally B. internally; from the ends of the chain C. from the 3' end of the chain; from the 5' end of the chain D. from the 5' end of the chain; from the 3' end of the chain

Biology & Microbiology

A small group of mice are released on an island without mice but with abundant food for mice and no predators. Initially, the growth of the mouse population will be limited mainly by what?

A. only density-dependent factors B. only density-independent factors C. the biotic potential D. the carrying capacity

Biology & Microbiology