The circulatory system of cephalopods is closed, whereas that of all other mollusks is open. Explain
the difference between open and closed circulatory systems, and describe how each system is adequate
for the groups possessing it. What will be an ideal response?
Concepts to Consider: An open circulatory system does not rely on a system of blood vessels to
transport circulatory fluids from one area to another. Rather, circulatory fluids bathe the coelom and
move via the body movements of the animal. In contrast, a closed system uses blood vessels to
transport fluids in the body. An open system suites sluggish mollusks such as gastropods and bivalves
because they have low metabolic requirements and can make do with the inefficiencies of an open
circulatory system. In cephalopods, a closed system is needed to ensure efficient transport of oxygen
and metabolites around the body, as these animals have high metabolic requirements.
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Explain what might occur when purine or pyrimidine bases in nucleotides undergo tautomeric shifts. What will be an ideal response?
The step of translation in which release factors bind to a stop codon is:
mitosis. termination. initiation. elongation. transcription
Annelids have ___.
a) a coelom b) a pseudocoelom c) no coleom d) none of the above
Coupled reactions are:
A) reactions in which endergonic reactions obtain the energy to go forward from exergonic reactions. B) any reactions that are accelerated by an enzyme. C) reactions that lower the activation energy of another reaction. D) reactions in which exergonic reactions obtain the energy to go forward from endergonic reactions.