Which feature would have given the jawed fish an evolutionary advantage over the jawless fish when it came time to hunt for food?
A. The evolution of an ectothermic lifestyle so they could regulate their body temperature based upon the environment.
B. A skin that is nonscaly that also allows for an increased respiration ability.
C. Gills that would increase the efficiency of their breathing.
D. A cartilaginous endoskeleton that would provide for more power while swimming.
E. The evolution of jaws from the gill slits that would enable them to bite more efficiently.
Answer: E
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The unique antigen-reactive proteins of T cells are
A) antibodies. B) immunoglobins. C) T cell receptors. D) None of these is correct.
You experimentally apply ?-bungarotoxin to a muscle and find that it does not contract when you electrically stimulate the motor neuron leading to it. You know that this toxin blocks acetylcholine receptors. Therefore, you suspect that the stimulation of contraction is failing at which of the following points?
A. A contraction fails to occur because acetylcholine is not released from the motor neuron. B. A contraction fails to occur because an action potential is not generated in the muscle cell. C. A contraction fails to occur because this toxin directly prevents calcium ion release from intracellular stores. D. A contraction fails to occur because neurotransmitter release by the motor neuron is blocked at the neuromuscular junction. E. A contraction fails to occur because this toxin prevents cross-bridge formation and thereby directly prevents contraction.
Veins from the ____ join together and form the hepatic portal vein
a. large intestine b. liver c. pancreas d. small intestine e. stomach
All of the following are involved in the transport system of the vascular plant EXCEPT
A. Xylem B. Tracheids C. Sporangia D. Vascular tissue