Section 6.8 Quiz

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. Infectious disease is thought to be a selective pressure on the maintenance of heterozygosity (variation of alleles) of MHC molecules within an individual and in a population.

True correct incorrect

False correct incorrect

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. Identify the FALSE statement about MHC diversity in humans.

It is based on selective maintenance of alleles within the human population. correct incorrect

It is due to pressure imposed by infectious pathogens. correct incorrect

It helps in displaying a large variety of peptides to CD4 and CD8 T cells. correct incorrect

It increases the number of individuals in the population who might have an MHC allele that is susceptible to infection. correct incorrect

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. The advantage of _____ is that more peptides from the pathogen can be displayed, providing a higher potential for T cells to be activated during infection.

MHC heterozygosity correct incorrect

somatic recombination correct incorrect

peripheral tolerance correct incorrect

central tolerance correct incorrect

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. Because MHC heterozygosity is advantageous in the body's defense against any given pathogen, it is selected for through _____.

balancing selection correct incorrect

directional selection correct incorrect

positive selection correct incorrect

negative selection correct incorrect

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. Which of the following tends to be the major evolutionary selective force on polymorphisms in a population due to the benefits of MHC heterozygosity?

Balancing selection correct incorrect

Directional selection correct incorrect

Positive selection correct incorrect

Negative selection correct incorrect

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. A shift in selective pressure, such as when a population is exposed to an emerging infectious disease that can drive selection of MHC molecule alleles that are most capable of presenting peptides, is referred to as _____.

directional selection correct incorrect

balancing selection correct incorrect

positive selection correct incorrect

negative selection correct incorrect

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. Which of the following results in a biased population in which the best alleles are maintained at the expense of heterozygosity?

Directional selection correct incorrect

Balancing selection correct incorrect

Positive selection correct incorrect

Negative selection correct incorrect

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. Self-MHC, or autologous, molecules work to help T cells distinguish self from non-self and prevent autoreactive T cells from leaving the thymus.

True correct incorrect

False correct incorrect

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. T-cell development only occurs in context of the MHC molecules expressed in each individual.

True correct incorrect

False correct incorrect

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. Allotype matching minimizes the risk of tissue rejection in a recipient in the case of a transplant.

True correct incorrect

False correct incorrect