Which characteristic is not true for an essential element?
a. It may play only one role in plant metabolism.
b. It is necessary for normal growth and reproduction.
c. It may be contained in plant seeds in high enough quantities to sustain the adult plant.
d. Occasionally, it can be functionally replaced by another element.
e. It may be required in only trace amounts.
ANSWER: d
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A proficient engineer can easily design skeletal structures that are more functional than those currently found in the forelimbs of such diverse mammals as horses, whales, and bats. The actual forelimbs of these mammals do not seem to be optimally arrange
d because _____. A) natural selection has not had sufficient time to create the optimal design in each case, but will do so given enough time B) in many cases, phenotype is determined by genotype and the environment C) though we may not consider the fit between the current skeletal arrangements and their functions excellent, we should not doubt that natural selection ultimately produces the best design D) natural selection is generally limited to modifying structures that were present in previous generations and in previous species
A (n) ________ vector contains promoters that result in high-level transcription of the gene cloned within a multicloning site.
A. expression B. shuttle C. chimeric D. phage
The time from absorption to release for T-even phage is about
A. 1 minute. B. 10 minutes. C. 30 minutes. D. 1 day.
Stephanie is infected with a pathogen. How might it be determined if the pathogen is a virus
or a bacterium?
a. A virus does not have genetic material such as DNA or RNA. b. A bacterium has ribosomes, but a virus does not. c. A virus does not have an outer covering or capsule. d. Bacteria are eukaryotes, and viruses are prokaryotes.