In Some (Although Not All)cases of Multiple Sclerosis,one of the First

question 168

Multiple Choice

In some (although not all) cases of multiple sclerosis,one of the first symptoms noticed is a reduction in sensation from distal parts of the body,such as feet and hands.Which of the following statements best explains why this might happen?

• A) The fibers of the axons are reduced in diameter,so the information can't travel fast enough.
• B) Without the myelin sheath covering the axon,the neural transmission from the periphery is slowed.
• C) The fibers of the axons are enlarged,slowing the neural transmission.
• D) The neurons have degenerated and are no longer producing neural transmission.

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Definitions:

Heritability

The proportion of observed variation in a particular trait, within a population, that can be attributed to inherited genetic factors as opposed to environmental influences.

Genome Wide Association

A study approach that involves rapidly scanning markers across complete sets of DNA, or genomes, of many people to find genetic variations associated with a particular disease.

Quantitative Trait Locus

A Quantitative Trait Locus (QTL) is a region of DNA that is associated with a particular phenotypic trait, which varies in degree and can be attributed to polygenic effects.

Genetically Divergent Populations

Populations that have accumulated genetic differences due to barriers to gene flow, resulting in genetic distinction from each other.