On the basis of this figure, multicellularity has evolved:
a. once. c. three times.
b. twice. d. at least six times.
D
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In describing the initiation and transmission of action potentials in neurons, it would be INCORRECT to say that
A. the rate of transmission of an action potential is directly related to the diameter of the axon. B. information about the intensity of a stimulus is conveyed by changes in the size of the action potential generated. C. the resting potential is maintained by differential ion permeabilities and the sodium-potassium pump. D. a stimulus to the neuron can either depolarize or hyperpolarize the neuronal membrane.
Why is the evolutionary origin of all eukaryotes no longer considered to be a simple evolution from a single Archaea species?
a. Archaea contain insufficient genetic material to explain eukaryotic evolution. b. Fossil records provide evidence that Archaea evolved after eukaryotes. c. Some eukaryotic genes share more similarity with Bacteria than Archaea. d. Some eukaryotes contain mitochondria, which are invariably fatal to Archaea.
The joint shown here is an example of _____
1.a fibrous joint
2.a joint held together by ligaments
3.a ball and socket joint
4.a cartilaginous joint
Although communities tend toward equilibrium, their most common state is one of dynamic response to changing conditions.
a. true b. false