Legumes are frequently grown in rotation with primary field crops. What is the benefit of this practice?
A) A greater amount of the primary crop can be harvested each year.
B) The legumes' symbiotic nitrogen-fixing bacteria add nitrogen to the soil.
C) Soil erosion is reduced by frequent plowing.
D) Legumes decrease the amount of organic material in the soil.
Answer: B
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Some birds follow moving swarms of army ants in the tropics. As the ants march along the forest floor hunting insects and small vertebrates, birds follow and pick off any insects or small vertebrates that fly or jump out of the way of the ants
This situation is an example of what kind of species interaction between the birds and the ants? A) cooperation B) consumption C) commensalism D) parasitism E) mutualism
At the end of the first meiotic division, each chromosome consists of
a. chiasmata. b. a homologous chromosome pair. c. four copies of each DNA molecule. d. two chromatids. e. a pair of polar microtubules.
Filter feeders
A. are carnivores. B. are the first organisms on a food chain. C. feed on plankton. D. are producers.
Which of the following characterizes Gram-positive bacteria?
a. the presence of an outer membrane b. the absence of ribosomes c. the presence of a thick cell wall d. the absence of a cell wall