Tube feet of sea stars, erectile tissue of the penis in vertebrates, and the bodies of cnidarians are all
supported by
a. an exoskeleton.
b. only nonskeletal structures.
c. a hydrostatic skeleton.
d. an endoskeleton.
e. joined exo- and endoskeletons.
C
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Explain how cells can adapt to colder temperatures by altering the number of double bonds in the lipids that comprise cell membranes
What will be an ideal response?All of the following are major components of the deep sea food web except:
a. detritus. b. nocturnal vertical migration to feed near the surface. c. larger predators feeding on the small deep sea organisms. d. photosynthesis. e. scavenging.
Why do some leaves change color (red, yellow, orange, etc.) in the fall?
A) The chlorophyll molecule is modified to absorb different wavelengths of light. B) The chlorophyll molecule breaks down and other pigments now become visible. C) When leaves die, the chlorophyll molecules are no longer visible. D) Cold weather denatures the chlorophyll molecule, and it begins to reflect different colors.
In any DNA molecule, the number of guanine bases will:
A) always be equal to the number of thymine bases. B) always be equal to the number of adenine bases. C) always be equal to the number of cytosine bases. D) sometimes be equal to the number of thymine bases and will sometimes be equal to the number of adenine bases. E) sometimes be equal to the number of cytosine bases and will sometimes be equal to the number of adenine bases.