Which statement is TRUE?
A. Myelin is a glycoprotein matrix, secreted by myelinating cells to speed nerve conduction.
B. Oligodendrocytes myelinate PNS axons.
C. Oligodendrocytes produce scar tissue upon corresponding axonal damage, preventing regrowth of the axon.
D. Schwann cells myelinate CNS axons.
E. Wallerian degeneration describes the CNS axon breakdown that may still enable regrowth and restoration of function.
Answer: C. Oligodendrocytes produce scar tissue upon corresponding axonal damage, preventing regrowth of the axon.
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Under the conditions of a given reaction, a positive ?G' means
A) the reaction is spontaneous. B) no energy needs to be added. C) the reaction is at equilibrium. D) work can be done. E) the reaction will not occur.
All of the following are true statements about life zones EXCEPT:
a. Life zones are very broad geographical regions with similar physical characteristics. b. Terrestrial life zones are typically described by the dominant type of vegetation. c. Animals typically moved readily between different life zones in a geographical area. d. Each continent is made up of many different life zones
Use of synthetic fertilizers often leads to the contamination of groundwater with nitrates. Nitrate pollution is also a suspected cause of anoxic "dead zones" in the ocean. Which of the following might help reduce nitrate pollution?
A) growing improved crop plants that have nitrogen-fixing enzymes B) adding nitrifying bacteria to the soil C) adding denitrifying bacteria to the soil D) using ammonia instead of nitrate as a fertilizer
In regard to the baby's colorblindness, a sex-linked recessive trait, you explain that
A) colorblindness often appears randomly, even if neither parent is colorblind. B) the baby's father must have a recessive allele for colorblindness. C) since colorblindness is sex-linked, a son can inherit colorblindness if his mother has the recessive colorblindness allele. D) the eggs must have been accidentally switched, since males inherit sex-linked traits only from their fathers.