Chapter 11 Flashcards
Incomplete Dominance
the dominant allele is not completely expressed when the recessive allele is around
Polygenic Traits
many genes coding for one trait
Sickle Cell Anemia Affects
hemoglobin
How does Sickle Cell Anemia affect the body?
some blood cells become sickle shapes and the elongated cells get stuck in certain blood vessels and parts of the body don’t get the oxygen they need
How does Sickle Cell Anemia happen?
it is caused by a single code letter change in DNA and that alters an amino acid in the hemoglobin protein
-Valine sits where glutamic acid should be in the hemoglobin protein
-Valine makes the hemoglobin molecules stick together forming long fibers that distort the shape of the red blood cells and that brings on an attack
According to Mendel’s law of segregation, __________.
allele pairs separate in gamete formation
Pea plants are tall if they have the genotype TT or Tt, and they are short if they have genotype tt. A tall plant is mated with a short plant. Which outcome below would indicate that the tall parent plant was heterozygous?
A 1:1 ratio of tall offspring to short offspring
A single genetic locus that controls more than one trait is said to be __________.
pleiotropic
When two average-height parents give birth to a child exhibiting achondroplasia, it is most likely due to a new mutation. This is because __________.
achondroplasia is caused by an allele that is always expressed; therefore, the parents must not have the allele
Flower color in snapdragons is an example of incomplete dominance. When a red-flowered plant is crossed with a white-flowered plant, the F1 generation has pink flowers. If a pink-flowered plant is crossed with another pink-flowered plant, the progeny plants will be __________.
25% red, 50% pink, and 25% white
Huntington’s disease is an example of a genetic disorder caused by __________.
a lethal dominant allele that afflicts an individual later in life
If an organism that is homozygous dominant is crossed with a heterozygote for that trait, the offspring will be __________.
all of the dominant phenotype
After obtaining two heads from two tosses of a coin, the probability of obtaining a head on the next toss is __________.
1/2
Which of the following human diseases is inherited as a simple recessive trait?
Cystic fibrosis
Tom’s brother suffers from phenylketonuria (PKU), a recessive disorder. The brothers’ parents do not have PKU. What is the chance that Tom, who is normal for this trait, is a carrier of PKU?
2/3
Tail length in a certain species of armadillo falls along a continuum, following a normal distribution. Assuming that environmental factors do not play an important role in determining tail length, this type of variation probably reflects __________.
polygenic inheritance
A woman with type O blood is expecting a child. Her husband is type A. Both the woman’s father and her husband’s father had type B blood. What is the probability that the child will have type O blood?
50%
If a heterozygous plant is allowed to self-pollinate, what proportion of the offspring will also be heterozygous?
1/2
Which of the following describes the expression of the Tay-Sachs allele in humans at the biochemical level?
Incompletely dominant
The probability of tossing three coins simultaneously and obtaining two heads and one tail is __________.
3/8
Heart disease, diabetes, cancer, alcoholism, and many mental illnesses can best be described as __________.
multifactorial disorders with a possible polygenic component
In Mendel’s monohybrid cross of purple-flowered and white-flowered peas, all members of the F1 generation had the __________ phenotype because their genotype was __________ at the flower-color locus.
purple-flowered; heterozygous
A red bull is crossed with a white cow and all of the offspring are roan, an intermediate color that is caused by the presence of both red and white hairs. This is an example of alleles that are __________.
codominant
Assume that in guinea pigs, the brown coat color allele (B) is dominant over red (b), and the solid color allele (S) is dominant over spotted (s). The F1 offspring of a cross between true-breeding brown, solid-colored guinea pigs and red, spotted guinea pigs are crossed. What proportion of their offspring (F2 generation) would be expected to be red and solid-colored?
3/16
