Compare and contrast the osmoregulatory challenges and solutions used by sharks and freshwater
fishes. What will be an ideal response?
Freshwater fishes live in a hypotonic environment; consequently, water continuously enters the body,
and salts diffuse out. To counteract these tendencies, the gills move some water out and actively
transport salts in. In addition, the kidneys excrete large volumes of dilute urine.
Marine cartilaginous fishes such as sharks and rays have evolved the ability to accumulate and tolerate
urea. The accumulation of urea makes their body fluids hypertonic to sea water, which results in an
inward flow of water via osmosis. The kidneys excrete excess salt and large volumes of dilute urine.
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Nuclear pores permit the passage of all the following except:
A. RNA only outward. B. proteins inward and outward. C. DNA molecules only outward.
Nutrient transport requires energy because the nutrients must be transported into the cell against a concentration gradient. The energy required for nutrient transport is supplied by
A) ATP. B) the proton motive force. C) phosphoenol pyruvate. D) ATP, the proton motive force, or phosphoenol pyruvate.
The role played by a species in its environment is called its
A. ecological niche. B. fundamental niche. C. realized niche. D. multidimensional niche. E. Hutchinsonian niche.
Courtship is often dependent on what?
A. An alarm call B. A stimulus/response chain C. Size and colors D. Social releasers E. Taxis