Vertebrates and tunicates share _____
A) jaws adapted for feeding
B) a high degree of cephalization
C) the formation of structures from the neural crest
D) an endoskeleton that includes a skull
E) a notochord and a dorsal, hollow nerve cord
Answer: E
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The protein complex that initiates the process of conjugation following contact between two bacteria is called the _________
A. origin of transfer B. T DNA C. relaxosome D. nucleoprotein
Which of the following accounts for the negative
control of operons? a. promoters b. repressors c. structural genes d. operators e. all of these
The tall ferns that we typically see in the tropics and temperate woodlands are the ________
A) sporophytes B) gametophytes C) gametes D) spores
Populations of amphibians, including frogs and toads, have been plagued by disease and high rates of deformity. A recent study investigated whether problems among the populations have arisen due to poisons from chemicals associated with agriculture. Biologists from the University of Florida collected local adult cane toads (Bufo marinus) from more than 20 different locations. Toads were collected from areas close to agriculture; both large-scale and small-scale farms as well as from suburbs. At collection sites where 50-97% of the adjacent land was farmed, males showed high levels of feminization. Feminized male toads were similar in color to females and had lower levels of testosterone and often also deformed gonads. These changes can lead to sterile males or changes in behavior that
prevent mating from occurring. Based on this study, what is the control group? What will be an ideal response?