Inheritance Patterns Quiz chapter 14,15

A couple has six children, all daughters. If the woman has a seventh child, what is the probability that the seventh child will be a daughter?

1/2

The pedigree below tracks Duchenne Muscular Dystrophy (DMD) through several generations. DMD is an X-linked recessive trait. If individuals I-1 and 1-2 had another son, what is the chance that he would have DMD?

100%

In llamas, coat color is controlled by a gene that exists in two allelic forms. If a homozygous yellow llama is crossed with a homozygous brown llama, the offspring have gray coats. If two of the gray-coated offspring were crossed, what percentage of their offspring would have brown coats?

25%

In cucumbers, warty (W) is dominant over dull (w), and green (G) is dominant over orange (g). In the P generation, a cucumber plant that is homozygous for warty and green is crossed with one that is homozygous for dull and orange. The resulting F1 generation is then crossed. If a total of 144 offspring is produced in the F2 generation, which of the following is closest to the number of dull green cucumbers expected?

28

In birds, sex is determined by a ZW chromosome scheme. Males are ZZ and females are ZW. A lethal recessive allele that causes death of the embryo is sometimes present on the Z chromosome in pigeons. What would be the expected sex ratio in the offspring produced in a cross between a male that is heterozygous for the lethal allele and a normal female?

2:1 male to female

Given the following recombination frequencies, what is the correct order of the genes on the chromosome? A-B, 8 map units; A-C, 28 map units; A-D, 25 map units; B-C, 20 map units; B-D, 33 map units

D-A-B-C

Which of the following is FALSE, regarding the law of segregation?

It is a method that can be used to determine the number of chromosomes in a plant

Which of the following statements about mitochondria is false?

Like nuclear genes, mitochondrial genes usually follow Mendelian patterns of inheritance

Which of the following observations accounts for why in a cross between two red-eyed flies, the white eyed phenotype is only observed in the male offspring?

The involved gene is on the X chromosome

When Thomas Hunt Morgan crossed his red-eyed F1 generation flies with each other, the F2 generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result?

The involved gene was on the X chromosome

Tallness (T) is dominant to dwarfness (t), while red (R) flower color is dominant to white (r). The heterozygous condition results in pink (Rr) flower color. A dwarf, red snapdragon is crossed with a plant homozygous for tallness and white flowers. What are the genotype and phenotype of the F1 individuals?

TtRr - tall and pink

The fact that all seven of the pea plants traits studied by Mendel obeyed the principle of independent assortment means that

all of the genes controlling the traits behaved as if they were on different chromosomes.

Following a successful IVF treatment, a couple discovers that their new son is color-blind and has type O blood. The couple claims that the child can't be theirs since the woman has type A blood and the man has type B. Also, neither parent is color-blind, although one grand-parent (the woman's father) is also color-blind. As a genetic counselor, you would explain to the parents that

each parent could have contributed one recessive allele resulting in type O blood.

Hydrangea plants of the same genotype are planted in a large flower garden. Some of the plants produce blue flowers and other pink flowers. This can be best explained by

environmental factors such as soil pH.

The pedigree below tracks the presence of attached earlobes through multiple generations. Having attached earlobes is an autosomal recessive trait. What is the genotype of individual II-3?

heterozygous - Ee

Which of the following observations about inheritance could only be explained after the discovery that genes may be linked on a chromosome?

in some crosses, most offspring had a combination of traits that was identical to that of either one parent or the other

A 1:2:1 phenotypic ratio in the F2 generation of a monohybrid cross is most likely a sign of

incomplete dominance.

X-linked conditions are more common in men than in women because

men need to inherit only one copy of the recessive allele for the condition to be fully expressed.

In regard to the baby's color blindness, you explain that

since color blindness is sex-linked, a son can inherit color blindness if his mother has the recessive color blindness allele

Mendel accounted for the observation that traits which had disappeared in the F1 generation reappeared in the F2 generation by proposing that

traits can be dominant or recessive, and the recessive traits were masked by the dominant ones in the F1