Assuming that the rate of sea-floor spreading was constant during the one-million-year period depicted above, on average Earth's magnetic field has undergone reversal once every _____
A) 25,000 years
B) 100,000 years
C) 250,000 years
D) 1,000,000 years
C
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Inserting a cloned gene for a plasma membrane transporter into crop plants could lead to
A. the ability of a plant to produce its own micronutrients. B. extra uptake of minerals that would fortify the crop for human consumption. C. the evolution of nodule-formation on the crop plant. D. elevated CO2 levels in the atmosphere. E. plants taking up enough minerals that they no longer need to photosynthesize.
Which of the following can act as opsonins on bacteria, thus enhancing phagocytosis?
What will be an ideal response?
What occurs during a lysogenic infection?
A. Viral particles attach to but do not penetrate a host cell. B. Viral particles fill a host cell and cause it to burst. C. Viral genetic material replicates in a host cell but does not cause symptoms. D. The viral prophage DNA is packaged into a protein coat.
What are the results of double fertilization?
A) Egg cell and sperm cell B) Diploid zygote and diploid endosperm C) Embryo sac and pollen sac D) Triploid endosperm and diploid zygote E) A zygote and an embryo