Chapter 8 & 9 test
An individual with (naturally) curly hair and an individual with (naturally) straight hair mate; all of their offspring have (naturally) wavy hair. If an individual with wavy hair mates with an individual with straight hair, what is the probability that their child will have curly hair?
0%
Assume that having three nostrils is inherited as a sex-linked trait on the Y chromosome. A man with three nostrils has a daughter who has a son with a man who has only two nostrils. What is the probability that the three-nostriled man's grandson has three nostrils?
0%
What would genetic counselors say is the probability that the second child will have the disease?
1/4
Attached earlobes are recessive to free earlobes. What genotypic ratio is expected when an individual with attached earlobes mates with an individual heterozygous for free earlobes?
1:1
Round seeds (R) are dominant to wrinkled seeds (r), and yellow seeds (Y) are dominant to green seeds (y). What is the expected phenotypic ratio of a cross between an RrYy and an rryy individual?
1:1:1:1
In humans, free earlobes (E) are dominant to attached earlobes (e) and the presence of freckles (F) is dominant to the absence of freckles (f). If an individual heterozygous for both of these traits were to mate with an individual with attached earlobes and no freckles, what is the probability of having a child with attached earlobes and freckles?
25%
A dihybrid cross produces 30 recombinant offspring out of a total of 1,000 offspring. What is the recombination frequency of the two gene pairs?
3%
A purebred plant that produces yellow seeds is crossed with a purebred plant that produces green seeds. The F1 plants have yellow seeds. What is the expected phenotypic ratio of seed color of the offspring of an F1 × F1 cross?
3:1
A couple has two female children. What is the probability that their next child will be male?
50%
Achondroplasia is a form of dwarfism caused by a dominant allele. The homozygous dominant genotype causes death, so individuals who have this condition are all heterozygotes. If a person with achondroplasia mates with a person who does not have achondroplasia, what percentage of their children would be expected to have achondroplasia?
50%
Attached earlobes are recessive to free earlobes. What is the probability of having a child with attached earlobes when an individual with attached earlobes mates with an individual heterozygous for free earlobes?
50%
Which of these crosses will only produce heterozygous offspring?
AA × aa
Hypophosphatemia (vitamin D-resistant rickets) is inherited as an sex-linked dominant trait. The relevant gene is found on the X chromosome. What is the expected outcome of a cross between a homozygous recessive woman and a man with hypophosphatemia?
All of their daughters and none of their sons exhibit hypophosphatemia.
The recombination frequency between gene B and gene C is 11%. The recombination frequency between gene B and gene D is 5%. The recombination frequency between gene C and gene D is 15%. What would be the arrangement of these genes on a linkage map?
DBC
In humans, the presence or absence of dimples is a trait controlled by a single gene. What is the genotype of an individual who is heterozygous for dimples?
Dd
Red-green color blindness is inherited as a sex-linked recessive trait. The gene is found on the X chromosome. How can a man with normal color vision father a daughter who is red-green color-blind?
He can't (unless there is a mutation).
______ genes violate Mendel's principle of independent assortment.
Linked
What is the key to the recognition of codominance?
The heterozygote expresses the phenotype of both homozygotes.
What is the key to the recognition of incomplete dominance?
The phenotype of the heterozygote falls between the phenotypes of the homozygotes.
What is the key to the recognition of a trait whose expression is determined by the effects of two or more genes (polygenic inheritance)?
The trait varies along a continuum in the population.
A purebred plant that produces yellow seeds is crossed with a purebred plant that produces green seeds. The seeds of all of the offspring are yellow. Why?
The yellow allele is dominant to the green allele.
Janice's genotype is _______.
WW or Ww
Mary has the genotype ______.
Ww
This pedigree supports the fact that widow's peak is due to a dominant allele, because if it were due to a recessive allele and both parents show the recessive phenotype, then ______.
all of the offspring would have a widow's peak
Alleles are described as ______.
alternate versions of a gene
An individual who is homozygous ______.
carries two copies of the same allele for a gene
An individual with the blood group genotype LMLN has the phenotype MN. What is the relationship between the LM and LN alleles?
codominance
According to Mendel's law of segregation, ______.
gametes have one copy of each allele
In humans, the inheritance of ______ is best explained as being polygenic.
height
Mendel crossed purebred purple-flowered plants with purebred white-flowered plants, and all of the resulting offspring produced purple flowers. The offspring are all ______, and the allele for purple flowers is ______.
heterozygotes... dominant
A mating between a purebred purple-flowered pea plant and a purebred white-flowered pea plant would produce a(n) ______.
hybrid
An individual with (naturally) curly hair and an individual with (naturally) straight hair mate; all of their offspring have (naturally) wavy hair. What is the relationship between the alleles for hair texture?
incomplete dominance
Many human traits, such as our performance on intelligence tests or our susceptibility to heart disease, are ______.
influenced by both genes and the environment
An individual heterozygous for cystic fibrosis ______.
is a carrier
To determine the genotype of an individual who expresses a dominant trait, you would cross that individual with an individual who ______.
is homozygous recessive for that trait
Linked genes are usually
located close together on a chromosome.
What name is given to the specific location of a gene on a chromosome?
locus
Marfan syndrome is the result of inheriting a single allele. Individuals with Marfan syndrome are tall and long-limbed, and have both cardiovascular and eye defects. The inheritance of Marfan syndrome is an example of ______.
pleiotropy
The best definition of a purebred plant is one that ______.
self-fertilizes to produce hybrid offspring
In the accompanying art you see a table with the actual number of offspring that resulted from a dihybrid cross. The numbers do not show the 9:3:3:1 ratio predicted. One phenotype occurred more than predicted; another occurred less. The reason could be because ______.
some of the alleles were linked
The ______ is most commonly found in nature.
wild-type trait
