The purine ______ always hydrogen bonds with the pyrimidine ________ in double-stranded DNA.

A. cytosine; guanine
B. adenine; guanine
C. thymine; guanine
D. guanine; cytosine


Answer: D

Biology & Microbiology

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Microorganisms are most nearly uniform in terms of chemical and physiological properties during ________ phase.

A. decline B. exponential C. lag D. stationary

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Which one of the following molecules is stored in adipose tissue and serves as an important source of energy for the human body?

A) glucose B) steroids C) glycogen D) triglycerides E) phospholipids

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An example of an enzyme is 

A. maltose. B. fructose. C. hydrogen peroxide. D. dehydrogenase.

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During an action potential, repolarization occurs _____

when sodium diffuses into the cell when potassium diffuses out of the cell when calcium ions diffuse into the synaptic knob only where sodium-potassium pumps are absent

Biology & Microbiology