Chapter 12 Study Guide
Pedigree
A graphic representation of an individuals family tree is a(n) ____.
PKU
A human genetic defect that results in the failure to metabolize phenylalanine is ______.
Aneupioidy
A karyotype can be valuable in pinpointing cases of ____.
50%
A man heterozygous for blood type A marries a woman heterozygous for blood type B. The chance that their first child will have type O blood is _____.
One
A phenotype that results from a dominant allele must have at least ________ dominant allele(s) present in the parent(s)
Polydactyly
A phenotypic trait that results from a single dominant allele is ____.
multiple alleles
A trait controlled by four alleles is said to have _____.
Both parents carried the recessive gene for cystic fibrosis
Two healthy parents produce a child with the genetic disorder of cystic fibrosis, which is the result of a recessive gene. What would be the best explanation for this inheritance?
the disorder is recessive and carried by both parents
A child is diagnosed with a rare genetic disease. Neither parent has the disease. How might the child have inherited the disorder?
25% black, 50% blue, 25% white
A cross between a white rooster and a black hen results in 100% blue Andalusian offspring. When two of these blue offspring are mated, the probable phenotypic ratio seen in their offspring would be _____.
50%
According to figure 12-5, what is the chance that individual A will be afflicted with Huntington's?
4
According to the pedigree in Figure 12-3, how many of the offspring in the III generation show the normal trait?
she was a carrier
Based on figure 11-2, what do you know about individual III-1's mother?
color blind father to pass the gene on to his son
Because the gene for red-green color blindness is located on the X chromosome, it is normally not possible for a _____.
sex-linked conditions
Both hemophilia and red-green color blindness are ____.
ethnic group
Cystic fibrosis and Tay-Sachs disease are typical of recessive disorders concentrated in ______.
true
Differing hormone levels among sexes can cause a single genotype to express more than PHENOTYPE
polygenic
Eye color in humans is the result of _______ inheritance.
Height
Examine the graph and figure 12-4, which illustrates the frequency in types of skin pigmentation in humans. Another human trait that would show a similar inheritance pattern and frequency of distribution is ______.
Dietary adjustments
Following the detection of PKU in an infant, the treatment used in order to prevent mental retardation is _____.
carriers
For the trait being followed in the pedigree, individuals II-1 and II-4 in Figure 12-1 can be classified as _____.
Autosomes
Humans have 22 pairs of ______ types of chromosomes.
50%
If a female fruit fly heterozygous for red eyes (XRXr) crossed with a white-eyed male (XrY), what percent of their offspring will have white eyes?
Caused by a recessive allele
In humans, red-green color blindness is ______.
Undergo progressive deterioration of the nervous system
Individuals with Hunting's disease
true
MORE THAN two phenotypes result from both multiple allelic inheritance and polygenic inheritance
recessive allele
Most human genetic disorders are caused by the expression of ________.
true
POLYGNIC inheritance occurs when there are more than two alleles for a single trait
0%
Refer to the figure 12-1. If the individual III-2 marry a person with the same genotype as I-1, what is the chance that their children will be afflicted by hemophilia ______.
sex-linked
Royal hemophilia is the result of _____________ inheritance.
Suffer tissue damage resulting from oxygen deprivation
Sickle-cell anemia Is a genetic disease common to human populations from Africa and the Mediterranean coast. The incidence is greater in these regions than elsewhere because the heterozygous state provides protection against malaria. Individuals afflicted with sickle-cell anemia ____.
sex chromosomes
The 23rd pair of chromosomes that differ in males and females are called __________.
multiple allelic
The blood types A, B, AB, and O are the result of _____ inheritance.
polygenic inheritance
The inheritance of traits that are controlled by two or more genes is _____.
Prior to birth, the mother's enzyme level prevents accumulation of the dangerous chemical
The reason a fetus afflicted with PKU is not affected until after birth is that _______.
incomplete dominance
The type of inheritance shown when a red-flowering plant is crossed with a white-flowering plant and only pink-flowering plants are produced is ______.
sex-linked traits
Traits controlled by genes located on the X or Y chromosomes are _______.
sex linkage
What is the probable mode of inheritance for the normal trait in Figure 12-3?
grandmother-grandson
What is the relationship between individual I-1 and individual III-2 in figure 12-1?
sex-linked
What type of inheritance pattern does the trait represented by the shaded symbols in Figure 12-1 illustrate?
Co-dominance alleles
When phenotypes of both homozygotes are produced in the heterozygote, they are called _____,
polygenic inheritance
When roan cattle are mated, 25% of the offspring are red, 50% are roan, and 25% are white. Upon examination, it can be seen that the coat of a roan cow consists of both red and white hairs. This trait is one controlled by ____.
Down syndrome and Turner syndrome
Which of the following genetic disorders can be detected by karyotyping?
The trait occurs by mutation
Which of the following situations is most usual for a dominant allele that results in severe effects in the offspring?
incomplete dominance
______ is when the phenotype of the heterozygous is intermediate between those phenotypes expressed by the homozygotes.
Huntington's disease
a human genetic disorder caused by a dominant gene is _____.