Slow sand filtration effectively removes ________.
A. viruses
B. most heavy metals
C. Giardia lamblia
D. Cryptosporidium parvum
Answer: C
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Germ layers are
A. layers infected with bacteria. B. embryonic layers with different developmental potentials. C. layers of cells surrounding the egg prior to fertilization. D. colonial protists arranged in layers. E. layers of gametes.
Could any of the dinosaurs have been omnivores, i.e. eating both plants and animals? Which results support this conclusion?
a. species 2 because of the lack of a definitive amount of any of the chemicals b. species 4 because the chemical amounts appear to be intermediate betweenthose typical for carnivores and herbivores c. species 1 because of the equal amounts of starch and proteins d. species 3 because of predominance of sugar, which is found in omnivores
All of the following are true concerning plasmids
EXCEPT that they a. are self-reproducing circular molecules of DNA. b. are sites for inserting genes for amplification. c. may be transferred between different species of bacteria. d. may confer the ability to donate genetic material when bacteria conjugate. e. are usually essential in bacteria.
Why is it important to preserve the genes of the wild relatives of crop plants?
A) It is not important because the human population no longer eats wild foods. B) Beneficial genes from the wild relatives may be transferred into crop plants. C) By preserving the genes, we can control the growth of the wild relatives, which threaten our crop plants. D) The wild relatives are the food sources for all domestic animal species. E) It is not important because the wild species have all become extinct.