Which of the following is a feature of the tube-within-a-tube body plan in most animal phyla?
A) The outer tube consists of a hard exoskeleton.
B) The outer tube consists of digestive organs.
C) The mouth and anus form the ends of the inner tube.
D) The two "tubes" are separated by tissue that comes from embryonic endoderm.
Answer: C
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What is a limitation of the tree of life phylogenetic model that necessitated the development of newer models?
a. It cannot explain the origin single-cell organisms. b. It cannot explain vertical gene transfer. c. It cannot explain horizontal gene transfer. d. It cannot explain development of organelles.
Hiking up an elevational gradient, you notice different species of birds becoming more dominant the higher you go. This could be because
A) older birds prefer lower elevations. B) competitive abilities change along environmental gradients. C) of population cycling. D) there are more predators at higher elevation.
What is the function of oxytocin?
a. to stimulate uterine contractions b. to stimulate the cells of the mammary glands to produce milk c. to regulate the permeability of the collecting tubules of the kidney d. to stimulate ovulation e. to stimulate the growth of the ovarian follicles
A channel that opens in response to the binding of a specific molecule, which is usually NOT the solute that passes through the channel is called a(n)_____.
a) positive-gated channel b) ligand-gate channel c) voltage-gated channel d) electric-gated channel e) charge-gated channel