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
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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
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
An example of an enzyme is
A. maltose. B. fructose. C. hydrogen peroxide. D. dehydrogenase.
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