How many nonindigenous species have been introduced to the United States?
A) 50
B) 500
C) 5,000
D) 50,000
E) 500,000
Ans: D) 50,000
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All of the following characteristics are shared between plant and animal development except that in animals, but not plants, _____
A) gene expression in developing embryonic tissues is closely regulated B) orientation of cells and tissues is critical for proper development C) differentiation of cells is directed and maintained by cascades of molecular signals D) once animal cells are differentiated, they cannot de-differentiate and redifferentiate
The visible indentation that forms on the exterior of a dividing animal cell is called the ________
a. cleavage furrow b. gray crescent c. contractile ring d. cell plate
Which statement best describes the limitations of using of humans in genetic studies of developmental biology?
A) The variation in human development between individuals is too large for genetic studies. B) It is impractical and unethical to conduct experimental manipulation or targeted mutagenesis of humans to examine the role of genes in development. C) It is impractical and unethical to examine and describe abnormalities of human development, such as birth defects. D) Genetic studies of human development are not necessary, because most problems in human development are due to environmental influences and not genetics.
Bacteriophages selectively infect bacterial cells. How might they be used as a therapeutic treatment in humans?
A. Bacteriophages can be used to genetically engineer bacterial cells making them more susceptible to drugs. B. Phages can be used to stimulate human immune cells to attack and kill bacterial cells. C. Phages can carry genes into cells which will genetically modify the host cells to prevent infection. D. Humans suffering from infections with antibiotic resistant bacteria can be treated with phages, which will infect and lyse the bacterial cells, leaving human cells unaffected.