Which of the following is not a mechanism to circumvent the limits imposed by diffusion?
A. placing metabolically active cells in the
interior of an organism and metabolically inert
structures along the exterior surface
B. using vascular tissue to transport materials
throughout the plant body
C. placing metabolically active cells along a
series of canals and pores
D. using a circulatory system to distribute
materials throughout the animal body
E. All of these options are mechanisms to
circumvent the limits of diffusion.
A
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Virus morphology does not include which of the following characteristics?
A. Shape B. Presence or absence of an envelope C. Size D. Host range
The effect of parathyroid hormone on blood chemistry is most directly opposed by the effect of
a. Thyroid-stimulating hormones. b. thyroxin. c. calcitonin. d. melatonin. e. cortisol.
Membranes that occur in paired sheets are classified as ____
a. serous b. cutaneous c. mucous d. synovial e. visceral
Under the conditions known as El Niño, the inorganic nutrient content of the seawater off the coast of Peru declines to very low levels. What effect will this likely have on marine life in the area?
A) The lower the levels of minerals, the less polluted the water; hence, most populations will increase. B) It will result in toxic red tides, which will reduce the populations of many species. C) It will reduce the abundance of phytoplankton and, consequently, the abundance of other organisms. D) It will increase the productivity of phytoplankton and, therefore, the productivity of other organisms by allowing sunlight to penetrate deeper into the ocean.