Practice Test 8

In pole beans, green pods (G) are a dominant trait, while yellow pods (g) are a recessive trait. A bean plant with a GG genotype is crossed with a second plant that has the gg genotype. If this cross produces 500 offspring, approximately how many of the offspring will have green pods?

• 0

• 125

• 250

• 500

In the image, the squares represent males, the circles females. The darkened shapes represent those who are affected. The diagonal line represents deceased subjects.

In the diagram, the undarkened circles represent

• normal males.

• normal females.

• affected males.

• deceased females.

The inheritance pattern of a disorder is illustrated in the pedigree chart. What type of genetic disorder is this?

• codominant

• autosomal recessive

• sex-linked recessive

• incomplete dominance

Based on the pedigree chart, what should you assume about the parental generation?

• The father was a carrier for a sex-linked disease.

• The mother was a carrier for a sex-linked disease.

• You cannot make any assumptions based on the pedigree chart.

• Both the father and mother were carriers of a sex-linked disease.

Turner's syndrome is a human female disorder characterized by short stature, obesity, and failure to mature sexually. It is caused by a missing X chromosome, so the affected person has only 45 chromosomes. They are always XO, as YO is a fatal condition prior to birth.

How can a genetic disorder, such as Turner's syndrome, occur?

• fragmentation

• a point mutation

• crossing over during meiosis

• nondisjunction during meiosis

Albinism is a genetic mutation that results in some animals being born without the enzyme that produces the pigment for skin and eye color. All BUT one statement is a possible explanation for this mutation. Which is NOT an explanation?

• A DNA base in the gene for the enzyme was removed.

• A DNA base in the gene for the enzyme was substituted.

• The wrong mRNA code caused the wrong protein to form.

• The organism gained an extra chromosome because of a non-disjunction.

In pigs, the allele for a wavy, rough coat (R) is dominant to the allele for a soft, fine coat (r). A rough coat boar and a soft coat sow mate. They produce several litters, 50% are rough coat and 50% are smooth coat. What were the genotypes of the parents?

• RR × rr

• Rr × rr

• RR × Rr

• Rr × Rr

When DNA is copied, sometimes a new, incorrect, base pairing appears within the structure of a new DNA molecule replacing original base pairs. This mistake is called a base-pair

• deletion.

• insertion.

• institution.

• substitution.

The Punnett square shown presents a cross between two piranha. Both parents have large teeth.

According to the chart, which combination describes the offspring expected from the cross?

• 50% large-toothed and 50% small-toothed

• 75% small-toothed and 25% large-toothed

• 75% large-toothed and 25% small-toothed

• 100% large-toothed

Some fruit flies are born with curly wings which makes them unable to fly. It has been shown that curly wings are caused by a dominant gene which can be represented by the symbol W, while the recessive normal wing gene is represented by the symbol w. If a parent fly with the genotype WW is crossed with a parent of the genotype Ww, what percentage the offspring will have curly wings?

• 100%

• 75%

• 50%

• 25%