The Irish potato famine in the mid-1840s was caused by a heterotrophic protist, Phytophthora infestans, which caused widespread infection of potato plants. It was successful in infecting because it was
A. a protozoan, with flagella, and swimming to potato plants in wet seasons, engulfing and digesting the potato cells.
B. a red algae, able to perform photosynthesis, allowing its cells to spread from the coast to potato farm fields.
C. a water mold, and its soft, fleshy filaments benefitted from several rainy seasons.
D. a diatom, with a silica shell allowing it to survive the soil conditions in which potatoes grow as specialized roots.
E. a ciliate, which has filaments very similar to water and slime molds.
C. a water mold, and its soft, fleshy filaments benefitted from several rainy seasons.
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Unique to flowering plants, the making of an embryo-nourishing ____ is an outcome of double fertilization
a. hypocotyl b. endosperm c. seed coat d. cotyledon e. epicotyl
All of these answers are true of A-B exotoxins except __________.
A) tThe B portion of the toxin binds to surface receptors on host cells B) they consist of two polypeptide components C) many exotoxins are A-B toxins D) the A portion of the toxin is the active component E) they are produced only by gram-negative bacteria
Which of the following statements concerning the Rh factor is CORRECT?
A. The Rh antigen is on white blood cells. B. Eighty-five percent of humans are Rh positive. C. Preexisting antibodies occur in 85% of the population. D. Rh antibodies are more abundant than the ABO antibodies. E. Eighty-five percent of the human population is Rh negative.
Which of the following microorganisms is the most commonly used indicator organism for water quality testing?
A. Escherichia coli B. Salmonella spp. C. Shigella spp. D. Campylobacter jejuni E. Hepatitis A virus