Of the given answer options, only cystic fibrosis is inherited via an autosomal recessive inheritance pattern. Color-blindness and hemophilia are both X-linked recessive disorders. Huntington's disease is an autosomal dominant disorder.

1 map unit equals 1% chance of recombination; therefore, 45% is the best answer.

FISH is useful for visualizing major changes in the genome, as described by the passage. Translocations and large copy number variants would likley be visible in color changes, while small single nucleotide polymorphisms (SNPs) would likely be less easily detected.

A frameshift mutation results in a change of the codon reading frame and results from the addition or deletion of a set of nucleotides that is not a multiple of three. If a mutation occurs that is a multiple of three, the reading frame is unchanged and a simple addition or deletion has occurred.

Template:               5'-AGC-CTT-AGC-3' 

Frameshift mutant:  5'-AGC-GCT-TAG-C-3' 

Point mutant:          5'-TGC-CTT-AGC-3'

Point mutant:          5'-AGC-CTT-AGG-3'

Deletion:                5'-CTT-AGC-3'

Insertion:               5'-TTT-AGC-CTT-AGC-3'

Note that all except the frameshift mutation contain sets of three nucleotides to create triplets. The frameshift leaves a singular, un-grouped cytosine.

This would be an example of a single nucleotide polymorphism. A fairly common variant is some change at a single base pair in human DNA. It is possible that this base pair change results in a modified protein that functions just as well as the normal protein in most conditions.

Some of these changes may, simply by chance, be better at resisting disease. When exposed to stress, such as a disease epidemic, it is possible this variant of normal becomes the most widespread genotype. This is especially noticeable in an isolated population, like a tribe in New Guinea. Note that not all single nucleotide polymorphisms will have positive effects, and in some cases can cause disease instead of resistance.

The question states that the individual with three sex chromosomes has a condition called polysomy. Recall that a normal individual will only carry two copies of a chromosome.

This abnormality occurs when meiosis isn’t carried out properly. A daughter cell from meiosis can contain an extra chromosome if sister chromatids don’t separate properly during anaphase II (a process called nondisjunction). This extra chromosome can be carried over to the offspring, giving rise to a polysomic individual.

Fertilization of two sperm cells with two eggs gives rise to fraternal twins (non-identical twins) and splitting of a single fertilized egg into two or more eggs gives rise to monozygotic twins (identical twins); therefore, you can eliminate these two answer choices. After meiosis, females always possess multiple polar bodies. During meiosis in females, most of the cellular content is transferred to a single daughter cell: the egg. The remaining daughter cells contain the remnants and are called polar bodies. These polar bodies don’t participate in development and fertilization.

This question is asking about the phase of Meiosis, during which disjunction (separation) of chromosomes normally occurs. While Metaphase can sometimes be a seductive answer, note that disjunction officially occurs during Anaphase.

This mutation replaced UAU (a coding codon) with UAG (a stop codon). The most descriptive term for this kind of replacement is a nonsense mutation.

Note that an easy way to remember the stop codons is UGA ("u" get away), UAA ("u" are away), and UAG ("u" are gone).

A nonsense mutation results in premature addition of a stop codon. A missense mutation is a point mutation that results in a different codon, which ultimately codes for a different amino acid in the polypetide sequence. A frameshift mutation results from and insertion or deletion of a nucleotide, resulting in a change in the reading frame. Frameshift mutations often indirectly result in nonsense mutations, but are not the best answer choice given.

Whenever a base pair is replaced by another base pair in the DNA double helix, it is referred to as a point mutation. If the amino acid is not changed by the mutation, we can refer to the mutation as a silent mutation, as the primary protein structure is not affected.

Point mutation: CATGA becomes CAGGA

Insertion mutations occur when additional bases are inserted into the DNA sequence.

Insertion mutation: CATGA becomes CATACTGA

Frameshift mutations can result from insertions or deletions when the number of nucleotides added/removed is not a multiple of three. Since codons are grouped by threes, any change that is not a multiple of three will alter the grouping of every codon downstream of the mutation, severly altering the primary protein structure.

Frameshift mutation: CATGA becomes CAATGA

A nonsense mutation results in a premature stop codon, and early translation termination. This can arise from a frameshift mutation, point mutation, insertion, or deletion.

Nonsense mutation: CATGA becomesCATTTAGA (When transcribed, this sequence becomes the mRNA UCUAAAUG, where UAA is a stop codon).