What percentage of the urea filtered by the kidneys is excreted in the urine?
a. 10 percent
b. 20 percent
c. 50 percent
d. 75 percent
e. 100 percent
ANSWER: c
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Synaptic potentials are due to the opening
a. voltage-gated ion channels b. chemically-gated ion channels
Hairs on the leaf on the yellow bush lupine act to ________
a. deter herbivores b. shelter nitrogen-fixing bacteria c. trap moisture d. feed ants that defend the plant
Usually, an egg cell from a human female contains
a. one X chromosome and one Y chromosome. b. one X chromosome. c. one Y chromosome. d. two X chromosomes. e. two Y chromosomes.
Which tissues are correctly matched to their progenitor germ layer? (Check all that apply.)
_____ ectoderm—lining of the digestive tract _____ ectoderm—epidermis _____ endoderm—lining of the respiratory tract _____ endoderm—muscles _____ mesoderm—blood vessels _____ mesoderm—gonads