Natural communities recycle nutrients, but cultivated communities often require an input of mineral nutrients due to losses through
A. erosion.
B. humus.
C. nitrogen fixation.
D. crop rotation.
E. iron accumulation.
A. erosion.
Practices associated with cultivation such as plowing and harvesting disrupt the topsoil layer. This leads to erosion and the loss of the topsoil.
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The causative agents of lumpy jaw are:
a. Clostridium spp. b. Bacteroides spp. c. Prevotella spp. d. Actinomyces spp.
In Drosophila, two maternal transcripts that are distributed evenly throughout the oocyte prior to fertilization are
A) caudal and knirps. B) bicoid and nanos. C) caudal and hunchback. D) sevenless and even-skipped.
Most fossils ____
a. are found in sedimentary layers of rock b. form without water c. contain remnants of soft body parts d. show evidence of extinct species e. are impervious to erosion
Sister chromatid exchanges increase in frequency in the presence of X-rays, certain viruses, ultraviolet light, and certain chemical mutagens. In what autosomal recessive disorder is there known to be an increase in sister chromatid exchanges?
A) Harlequin syndrome B) cystic fibrosis C) achondroplasia D) Bloom syndrome E) Huntington's disease