For humans and most vertebrates, the body is supported primarily by ____
a. an exoskeleton
b. only nonskeletal structures
c. a hydrostatic skeleton
d. an endoskeleton
e. joined exo- and endoskeletons
ANSWER: d
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Sucrose is composed of:
A. two ketose sugars. B. a six-carbon sugar and a five-carbon sugar. C. a simple sugar and a nucleotide. D. an aldose and a ketose. E. glycerol and three fatty acids.
Jet-lagged travelers are often advised to take ______ to restore their normal circadian rhythms
A. melatonin B. glucose C. calcitonin D. cortisol E. thyroxine
In the Gram-staining procedure, the decolorizer is
A. crystal violet. B. ethanol or acetone. C. safranin. D. iodine.
The tetanus toxin tetanospasmin blocks release of the neurotransmitter (GABA) that inhibits motor neurons and decreases muscle contraction
This causes persistence of the signal to contract and the resulting violent muscle contraction known as tetanic spasm. Compare the sustained contraction of muscle cells in rigor mortis with muscle contraction caused by the action of tetanospasmin on motor neurons. What will be an ideal response?