Which soil component(s) have a negative charge that attracts positively charged mineral ions in soil water?
a. sand
b. silt and sand
c. clay
d. humus
e. clay and humus
e
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The process by which microorganisms cause diseases is known as
A) pathogenesis. B) virulence. C) LD50 (lethal dose50). D) infection.
The purines of DNA are
A. adenine and guanine. B. thymine and adenine. C. serine and threonine. D. thymine and uracil. E. thymine and adenine AND thymine and uracil.
Newborn humans face thermoregulatory challenges as do small mammals. One mechanism they use to generate heat is
A. shivering thermogenesis in "brown fat." B. nonshivering thermogenesis in "brown fat." C. convection in "brown fat." D. evaporation in "brown fat." E. radiation in "brown fat."
The hormone __________ is involved in a positive
feedback cycle that results in strong uterine contractions during labor. a. estrogen b. oxytocin c. cortisol d. progesterone e. prolactin