When did the first plants evolved from algae?
A. 4.7 billion years ago
B. 470 million years ago
C. 470 thousand years ago
D. We do not know exactly when the first plants evolved from algae.
Answer: B
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Seagrasses are important in all the following except:
a. nutrient recycling. b. providing a habitat for animals. c. stabilizing sediments. d. being consumed by most estuarine herbivores.
Which of the following is not true of type III hypersensitivity?
A. Serum sickness is a systemic response. B. It involves an immune complex reaction. C. Antigen-antibody complexes are deposited in the basement membrane of epithelial tissues. D. It involves production of IgE antibodies. E. The Arthus reaction is a local response.
The technique of vaccination as developed by Jenner was an improvement over variolation because
A) cowpox was common in Europe at the time while smallpox was not. B) cowpox vaccination was not just preventative but could also cure an active case of smallpox. C) the smallpox virus mutates frequently but the cowpox virus does not. D) the cowpox virus used by Jenner was not fatal to humans but provided protection against smallpox. E) Jenner's technique required a lower rate of herd immunity to prevent the spread of smallpox.
Amoxicillin is very effective for treating infections with Gram-positive bacteria but rarely causes side effects in humans. This is an example of
A. selective toxicity. B. narrow spectrum of action. C. a broad-spectrum antimicrobial. D. antibiotic resistance. E. altruism.