Despite its name, Kentucky bluegrass is a widespread turfgrass used for lawns throughout the United States. In some regions, strains have developed desirable disease-resistant properties. However, Kentucky bluegrass typically develops by apomixis. Plant breeders say this creates both a challenge and an opportunity for engineering novel strains. Why?
A. Plants that develop by apomixis are naturally tolerant of herbicides. As a result, herbicide tolerance genes cannot be used as selectable markers for a transgene, but herbicides can be used to keep the resulting culture pure.
B. Since the progeny of apomixis are triploid, hybrids have an imbalance of parental genes. However, this may be desirable if a higher proportion of one allele is beneficial.
C. In apomixis, new plants develop from underground horizontal stems. This allows for fast propagation of new strains, but all progeny are identical to the parent.
D. If a seed develops by apomixis, it will be identical to its parent. Hybridization with another strain requires special techniques. However, once a hybrid strain is developed, apomixis ensures its reliable propagation.
Answer: D
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Bacteria transformed with plasmids are plated on growth medium containing ampicillin and X-gal. Blue colonies on
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a. recombinant; deleted from the plasmid b. nonrecombinant; intact c. recombinant; intact d. nonrecombinant; disrupted by the inserted DNA fragment e. recombinant; disrupted by the inserted DNA fragment
Many times species are composed of networks of distinct populations called metapopulations. When do metapopulations occur?
A. When a population is large and uniformly distributed. B. When a population in poor habitat continually sends out dispersers to bolster populations in better habitats. C. When a population in a better habitat does not send out colonizers into less suitable habitats. D. When suitable habitat is patchily distributed and separated by areas of unsuitable habitat.
An action potential is brought about by
a. a sudden membrane impermeability. b. the movement of negatively charged proteins through the neuronal membrane. c. the movement of lipoproteins to the outer membrane. d. a local change in membrane permeability caused by a greater-than-threshold stimulus. e. the movement of negatively charged amino acids through the neuronal membrane