About 80% of the alleles present in thoroughbred horses can be dated back to 31 known ancestors from the late eighteenth century. As a result, one would expect _____
A. random mating.
B. Hardy-Weinberg equilibrium.
C. low rates of mutation.
D. many polymorphic alleles.
E. little variation in physiology and behavior.
E. little variation in physiology and behavior.
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What is the difference between a genetically modified organism and a transgenic organism?
A. A transgenic organism contains only genes from other species, while a genetically modified organisms contains genes from its own species and genes from other species. B. A genetically modified organism is an organism that contains any foreign genes, while a transgenic organism has foreign genes that come from another species. C. A transgenic organism is an organism that contains foreign genes, while a genetically modified organism has foreign genes that come from another species. D. There is no difference between the two terms, they mean the same thing.
The genomes of Arabidopsis thaliana, a small member of the mustard family of plants, and rice, Oryza sativa, have been sequenced. The findings include
A. the genome for each is almost identical, indicating that they diverged in the fairly recent past. B. they each have very high copy numbers (slightly divergent copies of a gene), probably indicating episodes of polyploidy and/or segmental duplication. C. repetitive DNA, including retrotransposons, was a very small proportion of both genomes. D. more than 90% of the genes in each were particular to plants and not found in animal or fungal genomes.
How do spheroplasts and protosplasts differ?
A. Spheroplasts retain the peptidoglycan but protoplasts do not. B. Spheroplasts retain their outer membrane but protoplasts do not. C. Spheroplasts form from cocci and protoplasts form from bacilli. D. There is no difference; these terms are synonyms.
Angiosperms have a much higher water-transport capacity than that found in tracheid-only plants because:
A. the thinness of tracheids in angiosperms enhances their transport capability. B. the thin leaves of angiosperms allow them to transpire at a greater rate, moving more water. C. the specialization of cells into vessel elements and fibers allows transport and support to become separate functions. D. xylem in angiosperms is composed of living cells. E. the thin diameter of angiosperm vessels increases the rate of water flow.