When two eggs are fertilized by two different sperm, what type of twins is formed?
a. identical twins
b. fraternal twins
c. always same sex twins
d. conjoined twins
e. monozygotic
ANSWER: b
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The bacterium Alcaligenes eutrophus naturally produces polyhydroxybutyrate (PHB), a biodegradable thermoplastic. In 1992, Poirier, et al., reported in the journal Science that the two genes responsible for the production of PHB in bacteria had been introduced into the plant Arabidopsis thaliana, and it was demonstrated that the plants produced PHB. What type of vector was likely used to introduce the bacterial genes into the A. thaliana?
A. BAC. B. YAC. C. Ti plasmid. D. viral vector. E. BAC or YAC.
Which creatures belong to the Phylum Platyhelminthes? Check all that apply.
_____ planarians. _____ monogeneans. _____ tapeworms. _____ trematodes. _____ ctenophores.
In bacteria, fungi, and plants the high internal pressure generated by osmosis is counteracted by the mechanical strength of their
A. plasma membranes. B. organelles. C. cell walls. D. cytoskeletons.
Davis, Weintraub, and Lasser found three genes that are involved in muscle differentiation by
A. mutating genes expressed only in muscle cells to see if differentiation could be prevented. B. cloning all the genes that were expressed only in muscle cell lines to determine if any of these genes could cause non-muscle cells to differentiate into muscle cells. C. eliminating all the gene candidates that were expressed in both muscle and nonmuscle cells. D. finding all the genes that were expressed in common between two different muscle cell lines.