A scientist is searching for chemical compounds involved in embryonic limb development. He discovers a new compound that is transiently expressed in the limb, and only seems to affect cells in its immediate vicinity (up to a few cell lengths away)
How should the scientist
classify this chemical compound?
A. as an amine hormone
B. as a peptide hormone
C. as a steroid hormone
D. as a paracrine factor
E. as a neurotransmitter
D
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When comparing the genomes of a bacterial parasite versus a free-living, nonparasitic bacterium, one expects to find that _____
A) the proportion of G-C base pairs will be significantly higher in the parasite B) no homology between the free-living and parasitic bacteria C) there will be a higher proportion of genes of unknown function in the parasite D) the parasite will have acquired a smaller proportion of its genes through lateral gene transfer E) the parasite will have a smaller genome
Some scientists have suggested that recent outbreaks of sudden oak disease could be fought through the creation of transgenic plants with genetic resistance to sudden oak disease. What would be the most likely source of this genetic resistance?
A. a species of aphid with resistance to sudden oak disease B. entirely new genes created in a lab and inserted into the oak genome C. other tree species with unusually high levels of host plant resistance D. domesticated apple trees adapted to North America E. the original host species in the native region of the disease
Which of the following is composed of a 1:2:1 ratio
of carbon to hydrogen to oxygen? a. carbohydrate b. protein c. lipid d. nucleic acid e. steroid
Change in beak size over time in Darwin's finches is an example of
A) environmental gradient. B) fundamental niche. C) competitive exclusion. D) character displacement.