Understanding Polymorphisms - GRE Subject Test: Biology

Card 0 of 3

Question

What term best describes when one species exhibits two or more defined phenotypes within the same population?

Answer

The correct answer is polymorphism. A polymorphism refers to multiple phenoytpes (morphs) that exist within a population, generally as a result of multiple alleles for the same gene.

Sympatry and allopatry refer to mechanisms of speciation and natural selection favors a certain phenotype for its fitness or other survival advantages. Assortative mating describes a biased mating pattern based on either phenotype or behavior.

Compare your answer with the correct one above

Question

Which of the following is most accurate about single nucleotide polymorphisms (SNPs)?

Answer

In order for a nucleotide substitution to be considered a SNP and not a random mutation, it must occur in 1% or more of the population. SNPs are more frequently found in non-coding regions. Typically, SNPs are much less commonly found in AT-rich microsatellites.

Compare your answer with the correct one above

Question

What is the major difference between synonymous and non-synonymous substitutions?

Answer

If single nucleotide polymorphisms (SNPs) that occur in coding regions do not trigger an amino acid change in the protein, they are synonymous. A SNP can cause a missense mutation (an amino acid change in the protein) or a nonsense mutation (an amino acid change to a stop codon), both of these are nonsynonymous substitutions.

Compare your answer with the correct one above

Tap the card to reveal the answer