Echinoderms are members of the Bilateria but many members of the group (e.g., the sea stars) lack a brain, have no specialized sense organs, and have radial nerves that extend down each "arm" from a central nerve ring that surrounds the gut
What was a likely
selective pressure in the evolution of this type of nervous system?
A. ability to move forward
B. role as a predator in the ecosystem
C. multicellularity
D. possession of an endoskeleton of calcium
carbonate
E. None of the above.
E
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Explain the advantages of using recombinant DNA technology to produce human proteins in transgenic plants, animals, or cultured cells
What will be an ideal response?
. How many ATP molecules (net yield) are
produced per molecule of glucose during glycolysis?
a. 1 b. 2 c. 4 d. 36 e. 38
Why is Pacific salmon movement into freshwater streams considered migration if the salmon die at the head of the stream and never return to the ocean?
A) It is not considered migration but immigration. B) Migration is a one-way movement. C) Because their offspring return to the ocean, the entire population participates in the migratory event via different life stages. D) Most male adult fish survive reproduction and return to the ocean.
A segment of DNA that specifies a sequence of amino acids in a polypeptide is called a(n) ____________.
A. codon B. intron C. messenger D. gene E. enzyme